Article

Evidence of coseismic ruptures along the Roum fault (Lebanon): A possible source for the AD 1837 earthquake

August 2006
Journal of Structural Geology 28(8):1483-1495

DOI:10.1016/j.jsg.2006.03.038

Authors:

The Roum fault is the westernmost branch within the Lebanese restraining bend of the Dead Sea Transform Fault. This strike-slip fault extends for about 35 km from north of the Hula basin to the Awali river, and shows left-lateral strike-slip displacements (manifested as offset streams) and vertical movements. Recent seismic records indicate its seismogenic potential as the source of the double shock of 16 March 1956 (Ms 4.8, 5.1) earthquake. We studied the Roum fault using combined field investigations in geomorphology, structural geology, and palaeoseismology. Fresh fault scarps and pressure ridges visible along the fault trace attest to recent coseismic ruptures. A palaeoseismic trench investigation exposed a complex fault zone with several rupture strands and a minimum of four faulting episodes in the last ∼10,000 years, the most recent event being post 84–239 AD. According to historical records, the 1 January 1837 (Ms 7.1) earthquake, which induced severe damage in the region, is the most likely candidate. Our results assign a slip-rate of 0.86–1.05 mm/year along the Roum fault, which shows that it accommodates about 14% of the total predicted strike-slip motion within the Lebanese restraining bend, and it should be considered a potential seismogenic fault for seismic hazard estimates in Lebanon.

A fault‑based probabilistic seismic hazard model for Lebanon, controlling parameters and hazard levels

Article

Full-text available

Mar 2023
B EARTHQ ENG

The present work develops a comprehensive probabilistic seismic hazard study for Lebanon, a country prone to a high seismic hazard since it is located along the Levant fault system. The historical seismicity has documented devastating earthquakes which have struck this area. Contrarily, the instrumental period is typical of a low-to-moderate seismicity region. The source model built is made of a smoothed seismicity earthquake forecast based on the Lebanese instrumental catalog, combined with a fault model including major and best-characterized faults in the area. Earthquake frequencies on faults are inferred from geological as well as geodetic slip rates. Uncertainties at every step are tracked and a sensitivity study is led to identify which parameters and decisions most influence hazard estimates. The results demonstrate that the choice of the recurrence model, exponential or characteristic, impacts the most the hazard, followed by the uncertainty on the slip rate, on the maximum magnitude that may break faults, and on the minimum magnitude applied to faults. At return periods larger than or equal to 475 years, the hazard in Lebanon is fully controlled by the sources on faults, and the off-fault model has a negligible contribution. We establish a source model logic tree populated with the key parameters, and combine this logic tree with three ground-motion models (GMMs) potentially adapted to the Levant region. A specific study is led in Beirut, located on the hanging-wall of the Mount Lebanon fault to understand where the contributions come from in terms of magnitudes, distances and sources. Running hazard calculations based on the logic tree, distributions of hazard estimates are obtained for selected sites, as well as seismic hazard maps at the scale of the country. Considering the PGA at 475 years of return period, mean hazard values found are larger than 0.3 g for sites within a distance of 20–30 km from the main strand of the Levant Fault, as well as in the coastal region in-between Saida and Tripoli (≥ 0.4 g considering the 84th percentile). The study provides detailed information on the hazard levels to expect in Lebanon, with the associated uncertainties, constituting a solid basis that may help taking decisions in the perspective of future updates of the Lebanese building code.

The presence of extensional volcanic basins along a transpressive bend: a case of extension-transpression co-existence from the Lebanese Restraining Bend

Article

Feb 2023

Tony Nemer

The Lebanese Restraining Bend is 170 km long and lies obliquely along the N-S trending Dead Sea Transform Fault, which is the continental plate boundary between Arabia and Africa. Of particular attention about the Lebanese Restraining Bend is the presence of two basins in its southern and northern bounds that are bordered by basalts; these are the Hula basin and the Bouqayaa basin, respectively. These two basins and the presence of basalts in their vicinities raise questions about (1) their locations in the immediate proximity to a transpressive bend, (2) the tectonic interrelation between the formation of the basins and the emplacement of the basalts, and (3) the timing of the formation of the basins relative to the prevailing regional transpression. In this paper, the author sheds light on these aspects and proposes a simplistic kinematic model of the tectonics behind the transpressive regime, the formation of the basins, and the emplacement of the basalts. The presented model highlights the tectonic interrelation between the formation of the basins, their bordering basalts, and the deformation of the transpressive bend. The regional strike-slip movements along the faults outside and within the transpressive bend seem to have caused co-existing extensional and compressional regimes, and they suggest that the formation of the basins may be contemporaneous with the regional transpression. The results can serve as a conceptual model for more advanced boundary-element modeling and finite-element modeling of the tectonics of the Lebanese Restraining Bend, with potential broader insight into the understanding of the tectonics of transpressive bends and their interrelation with adjacent extensional basins, worldwide.

A fault-based probabilistic seismic hazard model for Lebanon, controlling parameters and hazard levels

Preprint

Full-text available

Jul 2022

The present work develops a comprehensive probabilistic seismic hazard study for Lebanon, a country prone to a high seismic hazard since it is located along the Levant fault system. The historical seismicity has documented devastating earthquakes which have struck this area. Contrarily, the instrumental period is typical of a low-to-moderate seismicity region. The source model built is made of a smoothed seismicity earthquake forecast based on the Lebanese instrumental catalog, combined with a fault model including major and best-characterized faults in the area. Earthquake frequencies on faults are inferred from geological as well as geodetic slip rates. Uncertainties at every step are tracked and a sensitivity study is led to identify which parameters and decisions most influence hazard estimates. The results demonstrate that the choice of the recurrence model, exponential or characteristic, impacts the most the hazard, followed by the uncertainty on the slip rate, on the maximum magnitude that may break faults, and on the minimum magnitude applied to faults. At return periods larger than or equal to 475 years, the hazard in Lebanon is fully controlled by the sources on faults, and the off-fault model has a negligible contribution. We establish a source model logic tree populated with the key parameters, and combine this logic tree with three ground-motion models (GMMs) potentially adapted to the Levant region. A specific study is led in Beirut, located on the hanging-wall of the Mount Lebanon fault to understand where the contributions come from in terms of magnitudes, distances and sources. Running hazard calculations based on the logic tree, distributions of hazard estimates are obtained for selected sites, as well as seismic hazard maps at the scale of the country. Considering the PGA at 475 years of return period, mean hazard values found are larger than 0.3g for sites within a distance of 20 to 30km from the main strand of the Levant Fault, as well as in the coastal region in-between Saida and Tripoli (≥ 0.4g considering the 84 th percentile). The study provides detailed information on the hazard levels to expect in Lebanon, with the associated uncertainties, constituting a solid basis that may help taking decisions in the perspective of future updates of the Lebanese building code.

Assessing the potential for reservoir induced seismicity from the Bisri dam project in Lebanon

Article

Apr 2022
ENG GEOL

Reservoir induced seismicity has been observed in multiple cases around the world. The Bisri dam project, planned to be constructed in the Bisri Valley in Lebanon, has overlooked the concerns for safety raised by experts, which puts thousands of people and various structures at risk. In this paper, we study the potential for reservoir induced seismicity from this project. We use a two-dimensional poroelastic model where fluid flow and solid deformation are coupled to estimate the change in Coulomb Failure Stress (CFS) and the rate of seismicity (R). The high permeability damage zone of the Bisri fault lies directly beneath the proposed reservoir, which allows the pore pressure to diffuse into deeper levels, decreasing the effective normal stress, destabilizing the fault, and increasing the seismicity rate. Our results show that the increase in the rate of seismicity remains decades after the initial impoundment indicating a high risk for protracted seismicity. Moreover, the activation of the Bisri fault can cause the reactivation of the Roum fault, which is a major and active branch of the Dead Sea Transform Fault that hosted the epicenters of recent and major seismic events in the region. Hence, the risk for induced seismicity from the Bisri project should be taken into consideration very seriously by the authorities.

A non-active fault within an active restraining bend: The case of the Hasbaya fault, Lebanon

Article

Apr 2020
J STRUCT GEOL

The Hasbaya fault is a 50-km-long fault branch of the Dead Sea Transform Fault within the Lebanese Restraining Bend. It lies within the intersection zone of Mount Lebanon and Anti-Lebanon chains, along the western flank of Mount Hermon. It is little studied, its tectonic behavior is unknown, and its role among the other active fault branches of the restraining bend is the least defined. It was mapped as a discontinuous array of fault segments, with minor displacements and tectonically undisturbed basaltic cover. We studied the Hasbaya fault with detailed field mapping, and combining geomorphology, structural geology, and active tectonic investigations. The results reveal little and localized faulting along the entire length of the fault, with no signs of tectonic correlation between the drainage network evolution and the tectonic activity of the fault. The absence of active-tectonic surface features along the Hasbaya fault trend indicates that it does not manifest enough surface evidence to be classified as a tectonically active structure within the Lebanese Restraining Bend, and subsequently does not appear to be a major source of seismic hazard in the region. It may be related to the subsurface structure that controls the monocline that forms the western flank of Mount Hermon, or it may represent the remnant of an old suture zone between Mount Lebanon and Anti-Lebanon as a part of the regional compression imposed across the restraining bend. Our results shed light on the role of the non-active Hasbaya fault in a zone of active faults within a restraining bend, which may provide a case with broader implications on comparable tectonic settings worldwide.

The Bisri dam project: A dam on the seismogenic Roum fault, Lebanon

Article

Aug 2019
ENG GEOL

Tony Nemer

The Roum fault is a fault branch of the Dead Sea Transform Fault within the Lebanese Restraining Bend. It is an active seismogenic fault that was associated with the 1 January 1837 (Ms 7.1) earthquake, and whose extent has been the subject of great controversy within the restraining bend. In this paper, the Roum fault is revisited after a dam project (the Bisri dam) has been planned in one of the fault's most critical locations, i.e. in the Bisri valley that hosted the epicenter of the 16 March 1956 (ML 5.8) earthquake. The fault and its associated structures in the proposed dam area are discussed, and highlights on the dam site are made as a geologically complex and tectonically active area. The future water body behind the planned Bisri dam will overlie an active fault, with huge potential for fault movement underneath the dam footprint, liquefaction around the dam foundations, mass movements near the dam site, and direct effect on inducing seismicity on a delicate fault system that can potentially trigger a major earthquake that can affect the whole Lebanon and its surroundings. This requires special attention and in-depth considerations especially of the potential of reservoir-induced/triggered seismicity on the seismogenic Roum fault, and makes of the Bisri area a very unfavorable site for the proposed Bisri dam in Lebanon.

Investigating the Geological Fault Framework Offshore Lebanon: Insight into the Earthquake Geology of the Eastern Mediterranean Region

Article

Full-text available

Aug 2023
PURE APPL GEOPHYS

The tectonic setting of Lebanon in the eastern Mediterranean region is a restraining bend along the Dead Sea Transform Fault, which is the plate boundary between Arabia and Africa. Within the Lebanese Restraining Bend, the plate boundary splays into several fault branches that are mapped onshore Lebanon and known to have contributed to the evolution of the Lebanese structural framework. Different models have been proposed about the geological structures offshore Lebanon, and how those structures could relate to the onshore tectonics. Based on 2D seismic reflection data, a previously interpreted thrust fault system offshore Lebanon referred to as “Mount Lebanon thrust” was suggested to be responsible for the 9 July 551 M 7.2 earthquake, which was one of the most destructive in the history of the Levant. This thrust system has been accepted as the main structure behind the offshore seismic activity. The objective of this paper is to use current 3D seismic reflection data in order to interpret the main tectonic structures offshore Lebanon, and to differentiate features formed by tectonic activity from others caused by different mechanisms such as subsurface salt movement. Such information is very useful in understanding the tectonic framework of the region from the earthquake geology perspective. A bathymetric map of the Lebanese offshore area was generated and used to delineate the seafloor features. Major and minor faults were interpreted and used to identify and understand the behavior of potential tsunami-generating structures. After careful investigation of the offshore area using the available 3D seismic data, the authors were not able to confirm the existence of Mount Lebanon thrust. Instead, they propose that the Latakia ridge that lies between Lebanon and Cyprus is a major and prominent structure that can trigger high-magnitude tsunamigenic earthquakes.

When faults diverge – High resolution imaging of an intra-fault zone in an urban environment. A case study from the city of Tiberias, Israel

Article

Nov 2021
ENG GEOL

The presence of active faults or potentially active faults in urban settings is of great concern to city planners and developers. The high value of property within cities means that it is not always possible to avoid construction in such areas. Thus, building codes exist in order to regulate where and how to build in the vicinity of such faults. The Israeli National Building Code defines a zone of active faulting as a 200-m wide area on each side of an active or potentially active fault trace. In this area, there is a high potential for repeated activity of undetected branches or secondary faults and construction should be avoided or built with extreme safety measures in place. The current study examines an area located between two fault strands – an active and a potentially active one - in the city of Tiberias, northern Israel. The area lies outside the active fault zones defined for each strand (i.e., at a distance of more than 200 m from each fault). Eight high-resolution ground penetrating radar (GPR) profiles were collected along the streets that crisscross this area. Results show a dense series of potential fault strands that reach the base of the artificial fill that was laid down for the construction of the roads, indicating potential seismic hazard in this seemingly “safe” zone, thus raising a “red flag” for construction plans in the area. A geological study should be conducted to validate the geophysical results. This study shows the importance in conducting a geophysical site survey in tectonically active settings, even in areas that lie outside well defined zones of active faulting.

Global Positioning System measurements of strain accumulation and slip transfer through the restraining bend along the Dead Sea fault system in Lebanon

Article

Full-text available

Jan 2007
GEOPHYS J INT

SUMMARY Approximately 4 yr of campaign and continuous Global Positioning System (GPS) measurements across the Dead Sea fault system (DSFS) in Lebanon provide direct measurements of interseismic strain accumulation along a 200-km-long restraining bend in this continental transform fault. Late Cenozoic transpression within this restraining bend has maintained more than 3000 m of topography in the Mount Lebanon and Anti-Lebanon ranges. The GPS velocity field indicates 4–5 mm yr−1 of relative plate motion is transferred through the restraining bend to the northern continuation of the DSFS in northwestern Syria. Near-field GPS velocities are generally parallel to the major, left-lateral strike-slip faults, suggesting that much of the expected convergence across the restraining bend is likely accommodated by different structures beyond the aperture of the GPS network (e.g. offshore Lebanon and, possibly, the Palmyride fold belt in SW Syria). Hence, these geodetic results suggest a partitioning of crustal deformation involving strike-slip displacements in the interior of the restraining bend, and crustal shortening in the outer part of the restraining bend. Within the uncertainties, the GPS-based rates of fault slip compare well with Holocene-averaged estimates of slip along the two principal strike-slip faults: the Yammouneh and Serghaya faults. Of these two faults, more slip occurs on the Yammouneh fault, which constitutes the primary plate boundary structure between the Arabia and Sinai plates. Hence, the Yammouneh fault is the structural linkage that transfers slip to the northern part of the transform in northwestern Syria. From the perspective of the regional earthquake hazard, the Yammouneh fault is presently locked and accumulating interseismic strain.

Variable slip-rate and slip-per-event on a plate boundary fault: The Dead Sea fault in northern Israel

Article

Jan 2018
TECTONOPHYSICS

We resolved displacement on buried stream channels that record the past 3400 years of slip history for the Jordan Gorge (JGF) section of the Dead Sea fault in Israel. Based on three-dimensional (3D) trenching, slip in the past millennium amounts to only 2.7 m, similar to that determined in previous studies, whereas the previous millennium experienced two to three times this amount of displacement with nearly 8 m of cumulative slip, indicating substantial short term variations in slip rate. The slip rate averaged over the past 3400 years, as determined from 3D trenching, is 4.1 mm/yr, which agrees well with geodetic estimates of strain accumulation, as well as with longer-term geologic slip rate estimates. Our results indicate that: 1) the past 1200 years appear to significantly lack slip, which may portend a significant increase in future seismic activity; 2) short-term slip rates for the past two millennia have varied by more than a factor of two and suggest that past behavior is best characterized by clustering of earthquakes. From these observations, the earthquake behavior of the Jordan Gorge fault best fits is a “weak segment model” where the relatively short fault section (20 km), bounded by releasing steps, fails on its own in moderate earthquakes, or ruptures with adjacent segments.

Earthquake damage history in Israel and its close surrounding - evaluation of spatial and temporal patterns

Article

Dec 2016
TECTONOPHYSICS

Israel was hit by destructive earthquakes many times in the course of history. To properly understand the hazard and support effective preparedness towards future earthquakes, we examined the spatial and temporal distribution of the resulted damage. We described in detail our systematic approach to searching the available literature, collecting the data and screening the authenticity of that information. We used GISs (Geographic Information Systems) to map and evaluate the distribution of the damage and to search for recurring patterns. Overall, it is found that 186 localities were hit, 54 of them at least twice. We also found that Israel was affected by 4, 17, 8 and 2 damaging earthquakes that originated, respectively, from the southern, central, central-northern and northern parts of the Dead Sea Transform (DST). The temporal appearance of the northern earthquakes is clustered; the central earthquakes are more regular in time, whereas no damage from the north-central and the central quakes, with the exception of the year 363 earthquake, seems to have occurred south of the Dead Sea region.

Measurement of Anomalous Radon Gas Emanation Across the Yammouneh Fault in Southern Lebanon: A Possible Approach to Earthquake Prediction

Article

Full-text available

Sep 2015

The eastern Mediterranean region is an active tectonic setting that includes the Dead Sea Transform Fault, which forms the boundary between the African and the Arabian Plates and crosses Lebanon from south to north, striking in a restraining bend around 25-30 degrees NE. The major structural feature in Lebanon is the Yammouneh Fault, which reaches to Syria and southern Turkey in a north-south direction. Measurements of radon gas concentration and exhalation rates in two locations along the southern segment of the Yammouneh Fault in south Lebanon were performed. Two profiles in the El-Khiam basin and Blat pull-apart basin and perpendicular to the Yammouneh Fault trace were analyzed. An approximate fault width 25-30 m wide was determined in the El-Khiam study area. Temporal increase of radon concentration was measured and correlated with stress/strain tectonic activity and stress drops along the studied fault segment boundary. Anomalous variable radon concentrations were detected during one of the measurements where an earthquake occurred in the region of Tiberias Lake in northern Palestine along the Yammouneh Fault in the study area. Measurements of radon concentration along a station's profile in Blat village did not show any radon anomalous variation due to the discontinuity along the fault (pull-apart), and possible absence of stress and energy accumulation along the Yammouneh Fault line in that location.

Estimating urban seismic damages and debris from building-level simulations: Application to the city of Beirut, Lebanon

Article

Full-text available

Sep 2023
B EARTHQ ENG

The estimation of seismic damages and debris at the urban scale-at a building-by-building level-is challenging for several reasons. First, commonly used methodologies for seismic damage estimation rarely take into account the local site effects, precisely at the building-level. Second, the available methods for debris estimation fail to estimate at the same time the quantity of debris generated per building according to its damage level and the distribution of the debris (extent and height) around buildings. Finally, the lack of comprehensive data on the building stock and the relevant building properties and their taxonomy further increases the complexity of assessing possible earthquake consequences at an urban scale. This paper addresses these challenges and proposes improvements to the assessment of seismic damages and debris from building-level simulations, along with the development of a 3D building model based on satellite images and heterogeneous data. These developments, 2 applied to the city of Beirut, Lebanon, highlight the control of the site effects on the seismic damage's spatial distribution throughout the city and the large volume and extent of debris to be expected in the city for a strong earthquake. Acknowledgements- We would like to thank the two anonymous reviewers for taking the necessary time and effort to review the manuscript. We also would like to thank the Centre National d'Etudes Spatiales (CNES) that kindly provided the set of very high-resolution Pleiades 1-B satellite images covering Beirut through the DINAMIS project. We also would like to thank Kamel Allaw for his contribution in the satellite images treatment.

The difficulty of estimating probabilistic seismic hazard for Lebanon

Conference Paper

Full-text available

Apr 2021

Keywords: Seismic hazard; Probabilistic forecasting; Lebanon. Probabilistic seismic hazard assessment (PSHA) consists in determining exceedance probabilities of given ground-motion levels, over future time windows. PSHA relies on source models, that describe the occurrence of future earthquakes, in terms of locations and magnitudes, and on ground-motion models, that predict the ground-motions that these future events may generate. In Lebanon, the observation datasets available both to model earthquake recurrence and to select ground-motion models are scarce. The instrumental catalog (since the sixties) is typical of a low-seismicity region, and is not representative of the large destructive earthquakes that occurred in the past. In the case of the capital city, Beirut, the hazard estimates are controlled by the Mount Lebanon Fault, that is difficult to characterize because located offshore. In this study, we derive seismic hazard estimates for Lebanon, using various input data (instrumental and historical catalogs, paleoseismology, active faulting), and exploring various source models, to highlight the difficulty of estimating hazard in this region, and to show how much the hazard estimates may vary depending on the input dataset and on the models.

Salt‐Detached Strike‐Slip Faulting, Outer Kwanza Basin, Offshore Angola

Article

Full-text available

Aug 2022
TECTONICS

We here use a 3D seismic reflection dataset from the Outer Kwanza Basin, offshore Angola to examine the structure and growth of salt‐detached strike‐slip faults. The faults occur in four, up to 13.8 km‐long, NE‐trending arrays that are physically linked by restraining bends and releasing stepovers, and which presently overlie Aptian salt and base‐salt relief related to pre‐salt faulting. We suggest that these faults formed to accommodate along‐margin variations in the rate and magnitude of differential seaward translation and salt diapirism, which commenced in the Early Cretaceous. We illustrate that the arrays grew by tip propagation of isolated fault segments, some of which linked during the Albian‐Cenomanian (i.e., 113–100.5 Ma, or the initial 11%–13% of their deformation history). Some arrays then reached their near‐final length within the subsequent ca. 77 Ma (or the next 69%–81% of their deformation history), while others attained this later, during the subsequent ca. 18 Ma (i.e., after 95% of their deformation history). During this time, the segments formed and then breached releasing and restraining stepovers, with the arrays as a whole growing by alternating periods of lengthening and throw accumulation, punctuated by phases of inactivity. Our results also show that scatter in the D‐L scaling of strike‐slip faults reflects the propagation, interaction, and linkage of individual segments.

Relative Structural Complexity of Plate‐Boundary Fault Systems Controls Incremental Slip‐Rate Behavior of Major Strike‐Slip Faults

Article

Full-text available

Nov 2021
GEOCHEM GEOPHY GEOSY

A comparison of published incremental fault slip rates from four major strike‐slip faults with the proximity and number of other active faults in the surrounding plate boundary systems shows that the behavior of the primary fault is correlated with the structural complexity of its tectonic setting. To do this, we characterize the relative structural complexity of the fault network surrounding a fault location of interest by defining the coefficient of complexity, which quantifies the density and displacement rates of the faults in the plate‐boundary network at specified radii around the site of interest. We show that the relative constancy of incremental slip rates measured along primary faults of the Alpine, San Andreas, North Anatolian, and Dead Sea fault systems reflects the proximity, number, and activity of their close neighbors. Specifically, faults that extend through more structurally complex plate boundary fault systems exhibit more irregular slip behavior than faults that pass through simpler settings. We suggest that these behaviors are likely a response to more complex stress interactions within more structurally complicated regional fault systems, as well as possible temporal changes in fault strength and/or kinematic interactions amongst mechanically complementary faults within a system that collectively accommodates overall relative plate motion. Our results provide a potential means for better evaluating the future behavior of large plate‐boundary faults in the absence of well‐documented incremental slip‐rate behavior, and may help improve the use of geological slip‐rate data in probabilistic seismic hazard assessments.

Hybrid Simulation of Near-Fault Ground Motion for a Potential Mw 7 Earthquake in Lebanon

Article

Sep 2021

Lebanon is a densely populated country crossed by major faults. Historical seismicity shows the potential of earthquakes with magnitudes >7, but large earthquakes have never been instrumentally recorded in Lebanon. Here, we propose a method to simulate near-fault broadband ground motions for a potential Mw 7 earthquake on the Yammouneh fault (YF)—the largest branch of the Dead Sea Transform fault that bisects Lebanon from north to south. First, we performed the first 3D tomography study of Lebanon using ambient noise correlation, which showed that Lebanon could be approximated by a 1D velocity structure for low-frequency (LF) ground-motion simulation purposes. Second, we generated suites of kinematic rupture models on the YF, accounting for heterogeneity of the rupture process, and uncertainty of the rupture velocity and hypocenter location. The radiated seismic energy was next propagated in the inferred 1D velocity model to obtain suites of LF ground motions (<1 Hz) at four hypothetical near-fault seismic stations. These LF simulations included the main features of near-fault ground motions, such as the impulsive character of ground velocity due to the rupture directivity or fling-step effects (so-called pulse-like ground motions). Third, to obtain broadband ground motions (up to 10 Hz), we proposed a hybrid technique that combined the simulated LF ground motions with high-frequency (HF) stochastic simulations, which were empirically calibrated using a worldwide database of near-fault recordings. Contrary to other hybrid approaches, in which the LF and HF motions are generally computed independently, the characteristics of stochastic HF ground motions were conditioned on those of LF ground motions (namely on the characteristics of the velocity pulse, if it existed, or on the absence of a pulse). The simulated peak ground accelerations were in agreement with the ones reported in the Next Generation Attenuation-West2 (NGA-West2) database for similar magnitude and distances and with three NGA-West2 ground-motion prediction equations.

Biostratigraphy, Depositional and Diagenetic Processes in Carbonate Rocks form Southern Lebanon: Impact on Porosity and Permeability

Article

Full-text available

Mar 2021
ACTA GEOL SIN-ENGL

Carbonate rocks contain prolific hydrocarbon reserves all over the world, particularly in the Middle East. For exploration and production strategies, it is essential to understand the carbonate reservoirs in terms of their internal characteristics, depositional environment, relative age, diagenetic processes, and their impact on petrophysical properties. This study has been performed on exposed Cretaceous, Paleocene, and Miocene marine carbonate sedimentary sequences in two localities (Maghdoucheh and Qennarit) near the city of Sidon (Southern Lebanon). It represents the first comprehensive study considering the carbonate reservoir facies, diagenetic history, and reservoir quality in the area. Rocks at Maghdoucheh are mainly dominated by limestone beds showing tractive structures and erosive bases alternated with microfossil‐rich silty marls related to a shallowing upward sequence in a restricted marine platform environment. Shells of benthic foraminifera and mollusks dominate the fossil assemblage extracted from the studied rocks. The microfossil and nannofossil assemblage detected in Maghdoucheh sections reveal a middle Miocene age. Rocks at Qennarit are composed of mudstone/wackestone limestone beds rich in planktonic foraminifera and nanofossils related to open marine conditions. Based on the nannofossil content, rocks from Qennarit 1 and 2 are Paleocene and Cretaceous in age, respectively. Four main types of microfacies have been identified, i.e. 1) Microbioclastic peloidal calcisiltite, 2) Pelagic lime mudstone and wackestone with planktonic microfossils, 3) Grainstone/Packstone with abundant foraminifera and 4) Fenestral bindstones, mudstones and packstones with porostromate microstructures. The porosity‐permeability (poro‐perm) analysis of representative samples reveals moderate to good porosity but very low permeability. This is mainly due to the presence of high moldic pores that are isolated in nature. The diagenetic features are dominated by micritization and dissolution (both fabric selective and non‐fabric selective). Among all diagenetic features, dissolution in both localities contributes to porosity enhancement, while micritization, cementation, compaction, and the filled fractures have negative impacts on permeability; hence the overall reservoir quality.

Neotectonics of the Sea of Galilee (northeast Israel): implication for geodynamics and seismicity along the Dead Sea Fault system

Article

Full-text available

Jul 2020

The Sea of Galilee in northeast Israel is a freshwater lake filling a morphological depression along the Dead Sea Fault. It is located in a tectonically complex area, where a N-S main fault system intersects secondary fault patterns non-univocally interpreted by previous reconstructions. A set of multiscale geophysical, geochemical and seismological data, reprocessed or newly collected, was analysed to unravel the interplay between shallow tectonic deformations and geodynamic processes. The result is a neotectonic map highlighting major seismogenic faults in a key region at the boundary between the Africa/Sinai and Arabian plates. Most active seismogenic displacement occurs along NNW-SSE oriented transtensional faults. This results in a left-lateral bifurcation of the Dead Sea Fault forming a rhomb-shaped depression we named the Capharnaum Trough, located off-track relative to the alleged principal deformation zone. Low-magnitude (ML = 3–4) epicentres accurately located during a recent seismic sequence are aligned along this feature, whose activity, depth and regional importance is supported by geophysical and geochemical evidence. This case study, involving a multiscale/multidisciplinary approach, may serve as a reference for similar geodynamic settings in the world, where unravelling geometric and kinematic complexities is challenging but fundamental for reliable earthquake hazard assessments.

Interaction between fault and off-fault seismic sources in hazard analysis – A case study from Israel

Article

Jun 2020
ENG GEOL

In this study, seismic source characterization (SSC) for purpose of seismic hazard analysis (SHA) is explored, with a focus on the moment balance and interaction between on-fault and off-fault seismicity. For the purpose of this study, a homogenous, uniform, earthquake catalog for Israel is first compiled and de-clustered. Gridded seismicity is calculated based on the de-clustered catalog, using a fixed kernel, as well as an adaptive kernel. The main faults are represented as planar features and their magnitude-frequency distribution is adjusted to match both the geological and the seismological available data. A full probabilistic seismic hazard analysis (PSHA) is then conducted for the entire state of Israel. Results are presented both in terms of the full spatial distribution, in the form of hazard maps, as well as at specific point locations - near and far from the main sources. Our results show that, based on the available data and balancing seismic moment, the characteristic portion of the main seismic sources in Israel is larger than the classical 94% (Suggested by Youngs and Coppersmith 1985) and is about 96%–98%, depending on the fault. This suggests that the exponential model, as currently used in the building code, leads to a significant underestimation of hazard. We further show that as long as the moment is balanced, hazard results are only mildly sensitive to model choices, such as size of kernel, or type of cutoff between on-fault and off-fault sources. Finally, we suggest using the adaptive-kernel with the Fault-extract interaction, which we believe is the best representation of the currently available geological, seismological and geodetic information.

Assessment of seismic sources and capable faults through hierarchic tectonic criteria: implications for seismic hazard in the Levant

Article

Full-text available

Jan 2020
NAT HAZARD EARTH SYS

We present a methodology for mapping faults that constitute a potential hazard to structures, with an emphasis on ground shake hazards and on surface rupture nearby critical facilities such as dams and nuclear power plants. The methodology categorises faults by hierarchic seismo-tectonic criteria, which are designed according to the degree of certainty for recent activity and the accessibility of the information within a given region. First, the instrumental seismicity is statistically processed to obtain the gridded seismicity of the earthquake density and the seismic moment density parameters. Their spatial distribution reveals the zones of the seismic sources, within the examined period. We combine these results with geodetic and pre-instrumental slip rates, historical earthquake data, geological maps and aerial photography to define and categorise faults that are likely to generate significant earthquakes (M≥6.0). Their mapping is fundamental for seismo-tectonic modelling and for probabilistic seismic hazard analyses (PSHAs). In addition, for surface rupture hazard, we create a database and a map of Quaternary capable faults by developing criteria according to the regional stratigraphy and the tectonic configuration. The relationship between seismicity, slip dynamics and fault activity through time is an intrinsic result of our analysis that allows revealing the dynamic of the deformation in the region. The presented methodology expands the ability to differentiate between subgroups for planning or maintenance of different constructions or for research aims, and it can be applied in other regions.

Evaluating earthquake-induced rockfall hazard near the Dead Sea Transform

Article

Full-text available

Apr 2019
NAT HAZARD EARTH SYS

We address an approach for rockfall hazard evaluation where the study area resides below a cliff in an a priori exposure to rockfall hazard, but no historical documentation of rockfall events is available and hence important rockfall hazard parameters like triggering mechanism and recurrence interval are unknown. We study the rockfall hazard for the town of Qiryat Shemona, northern Israel, situated alongside the Dead Sea Transform, at the foot of the Ramim escarpment. Numerous boulders are scattered on the slopes above the town, while pre-town historical aerial photos reveal that boulders had reached the location that is now within town limits. We use field observations and optically stimulated luminescence dating of past rockfall events combined with computer modeling to evaluate the rockfall hazard. For the analysis, we first mapped the rockfall source and final downslope stop sites and compiled the boulder size distribution. We then simulated the possible rockfall trajectories using the field observed data to calibrate the simulation software by comparing simulated and mapped boulder stop sites along selected slopes, while adjusting model input parameters for best fit. The analysis reveals areas of high rockfall hazard at the southwestern quarters of the town and also indicates that in the studied slopes falling blocks would stop where the slope angle decreases below 5–10∘. Age determination suggests that the rockfalls were triggered by large (M>6) historical earthquakes. Nevertheless, not all large historical earthquakes triggered rockfalls. Considering the size distribution of the past rockfalls in the study area and the recurrence time of large earthquakes in the region, we estimate a probability of less than 5 % to be affected by a destructive rockfall within a 50-year time window. Here we suggest a comprehensive method to evaluate rockfall hazard where only past rockfall evidence exists in the field. We show the importance of integrating spatial and temporal field observations to assess the extent of rockfall hazard, the potential block size distribution and the rockfall recurrence interval.

Evaluating earthquake-induced rockfall hazard by investigating past rockfall events: the case of Qiryat-Shemona adjacent to the Dead Sea Transform, northern Israel

Article

Full-text available

Sep 2018

We evaluate rockfall hazard for the town of Qiryat-Shemona, northern Israel, situated alongside the Dead Sea Transform, at the foot of the Ramim escarpment. Boulders of 1m³ to 125m³ are scattered on the slope above town, while historical aerial photos reveal that before town establishment, numerous boulders had reached the town premises. For the hazard analysis we first mapped the rockfalls, their source and their downslope final stop-sites, and compiled the boulder size distribution. We then simulated the probable future rockfall trajectories using the field observed data to calibrate the simulation software by comparing simulated vs mapped boulders stop-sites along selected slopes while adjusting model input parameters for best fit. The analysis identified areas of high rockfall hazard at the south-western quarters of the town and also indicates that in the studied slopes, falling blocks would stop after several tens of meters where the slope angle is below 10°. OSL age determination of several past rockfall events in the study area suggests that these rockfalls were triggered by large (M>6) historical earthquakes. Nevertheless, not all large historical earthquakes triggered rockfalls. Simulations show that downslope reach of the blocks is not significantly affected by the magnitude of seismic acceleration. Considering the size distribution of the past rockfalls in the study area and the reoccurrence time of large earthquakes in the region, the probability to be affected by a destructive rockfall within a 50 year time-window is of less than 5%.

Developing a seismic source model for the Arabian Plate

Article

Aug 2018

A seismic source model is developed for the entire Arabian Plate, which has been affected by a number of earthquakes in the past and in recent times. Delineation and characterization of the sources responsible for these seismic activities are crucial inputs for any seismic hazard study. Available earthquake data and installation of local seismic networks in most of the Arabian Plate countries made it feasible to delineate the seismic sources that have a hazardous potential on the region. Boundaries of the seismic zones are essentially identified based upon the seismicity, available data on active faults and their potential to generate effective earthquakes, prevailing focal mechanism, available geophysical maps, and the volcanic activity in the Arabian Shield. Variations in the characteristics given by the above datasets provide the bases for delineating individual seismic zones. The present model consists of 57 seismic zones extending along the Makran Subduction Zone, Zagros Fold-Thrust Belt, Eastern Anatolian Fault, Aqaba-Dead Sea Fault, Red Sea, Gulf of Aden, Owen Fracture Zone, Arabian Intraplate, and a background seismic zone, which models the floating seismicity that is unrelated to any of the distinctly identified seismic zones. The features of the newly developed model make the seismic hazard results likely be more realistic.

HISTORICAL EARTHQUAKES AROUND THE SEA OF GALILEE

Chapter

Jul 2018

High-resolution stratigraphy and multiple luminescence dating techniques to reveal the paleoseismic history of the central Dead Sea fault (Yammouneh fault, Lebanon)

Article

Apr 2018
TECTONOPHYSICS

Continuous sedimentation and detailed stratigraphy are key parameters for a complete paleo-earthquake record. Here, we present a new paleoseismological study across the main strike-slip fault branch of the Dead Sea fault in Lebanon. We aim to expand the current knowledge on local paleoseismicity and seismic behavior of strike-slip plate boundary faults and to explore the limitations of paleoseismology and dating methods. The trench, dug in the Jbab el-Homr basin, reveals a succession of remarkable, very thin (0.1 to 5 cm) palustrine and lacustrine layers, ruptured by at least 17 earthquakes. Absolute ages of 4 samples are obtained from three luminescence-dating techniques targeting fine-grain minerals. Blue-green stimulated luminescence (BGSL) on quartz and post-infrared infrared-stimulated luminescence at 225 °C on polymineral aliquots led to consistent ages, while ages from infrared-stimulated luminescence at 50 °C on polymineral aliquots appeared underestimated. The quartz BGSL ages are 26.9 ± 2.3 ka at 0.50 m depth and 30.8 ± 2.9 ka at 3.65 m depth. During this time period of 3.9 ka ([0; 9.1 ka]), 14 surface-rupturing events occurred with a mean return time of 280 years ([0; 650 years]) and probable clustering. This return time is much shorter than the 1127 ± 135 years return time previously determined at the Yammouneh site, located 30 km south. Although fault segmentation and temporal variations in the earthquake cycle remain possible causes for such different records, we argue that the high-resolution stratigraphy in Jbab is the main factor, enabling us to record small deformations related to smaller-magnitude events that may have been missed in the rougher strata of Yammouneh. Indeed, focusing only on larger events of Jbab, we obtain a mean return time of 720 years ([0; 1670 years]) that is compatible with the Yammouneh record.

The recent instrumental seismicity of Syria and its implications

Article

Full-text available

Apr 2018

This contribution is an attempt to enlarge the current knowledge about the recent instrumental seismicity, recorded during the period 1995-2012 by the Syrian national seismological network, as well as the seismotectonic settings in Syria. The recent instrumental seismicity has shown that the earthquake activity has produced a little number of low magnitude events. Consequently, it indicates that this activity is actually passing through a relative quiescence in comparison with the historical seismicity. The correlation between the instrumental seismicity and the seismotectonic features was performed by analyzing spatial distributions of seismic events and focal mechanisms of some strongest events. The current results, allow observing many types of the seismic activity as follows: Swarm-type, Cluster-type, and Occasional-type, which could improve the understanding of the behavior of the seismically active faults. The long return periods of large earthquakes (M≥5) and the shortness of instrumental seismicity, prevent us to completely characterize the seismic activity and to discover all the active faults in the country.

The recent instrumental seismicity of Syria and its implications

Article

Full-text available

Apr 2018

Mohamad Khir Abdul-Wahed

This contribution is an attempt to enlarge the current knowledge about the recent instrumental seismicity, recorded during the period 1995-2012 by the Syrian national seismological network, as well as the seismotectonic settings in Syria. The recent instrumental seismicity has shown that the earthquake activity has produced a little number of low magnitude events. Consequently, it indicates that this activity is actually passing with a relative quiescence in comparison with the historical seismicity. The correlation between the instrumental seismicity and the seismotectonic features is performed by analyzing of spatial distributions of seismic events and focal mechanisms of some strongest events. The current results, presented in this paper, have allowed observing many types of the seismic activity as follows: Swarm-type, Cluster-type, and Occasional-type, which could improve the understanding of the behavior of the seismically active faults. The long return periods of large earthquakes (M≥5) and the shortness of instrumental seismicity prevent us to completely characterize the seismic activity and to discover all the active faults in the country. Key words: Instrumental seismicity, Dead Sea Fault System, Swarm, Syria.

רעשי אדמה היסטוריים בצפון ישראל והשפעתם על היפוס־סוסיתא Historical Earthquakes in Northern Israel and their Impact on Hippos-Sussita

Article

Dec 2017

Sitting on top of a hill overlooking the Sea of Galilee, the ancient city of Hippos-Sussita has been repeatedly struck by strong earthquakes. These tremblors caused typical damage to the masonry, such as directional collapsing of walls and toppling of columns, which have been exposed in archaeological excavations. The source of the earthquakes is the nearby Dead Sea Fault, an active plate boundary between the Arabian and Sinai plates, which transfers the opening of the Red Sea to the collision at the Zagros and Taurus mountain belt. We compare the archaeological evidence with historical records of earthquakes and geological evidence of ground movements in the region in order to understand the spatio-temporal patterns of seismic activity in northern Israel.

Quantifying Earthquake Effects on Ancient Arches, Example: The Kalat Nimrod Fortress, Dead Sea Fault Zone

Article

May 2016

Deformed arches are often key elements of archaeoseismic studies; arches have been in use for more than three millennia and damage, particularly moved keystones, are clear indications of a seismogenic cause. We introduce a damage evaluation scheme that allows a straightforward determination of the degree of damage to an arch based on laser scan models and digital images. The scheme is applied to 90 arches of the Nimrod Castle, which is neighboring the Dead Sea fault and which was heavily damaged during the 1759 Lebanon earthquake. The analysis shows that the a priori assumption of a correlation between arch orientation and damage degree does not hold for the entire building. An exception is a large tower including a secret passage in which voussoirs have dropped along a more than 20 m long section.

Paleoseismic History of the Dead Sea Fault Zone

Book

Aug 2015

Mustapha Meghraoui

The aim of this entry is to describe the DSF as a transform plate boundary pointing out the rate of activedeformation, fault segmentation, and geometrical complexities as a control of earthquake ruptures. Thedistribution of large historical earthquakes from a revisited seismicity catalogue using detailedmacroseismic maps allows the correlation between the location of past earthquakes and fault segments.The recent results of paleoearthquake investigations (paleoseismic and archeoseismic) with a recurrenceinterval of large events and long-term slip rate are presented and discussed along with the identification ofseismic gaps along the fault. Finally, the implications for the seismic hazard assessment are also discussed.

Timing of earthquake ruptures at the Al Harif Roman aqueduct (Dead Sea fault, Syria) from archaeoseismology and paleoseismology

Chapter

Oct 2010

We studied the faulted Al Harif Roman aqueduct, located on the north-trending, ∼90-km-long Missyaf segment of the Dead Sea fault, using four archaeological excavations, three paleoseismic trenches, and the analysis of six tufa cores. Damage to the aqueduct wall exhibits successive left-lateral fault offsets that amount to 13.6 ± 0.2 m since the aqueduct construction, which is dated younger than 65 B.C. Radiocarbon dating of sedimentary units in trenches, building cement of the aqueduct wall, and tufa cores constrain the late Holocene aqueduct history. The building stone types, related cement dating, and tufa deposits of the aqueduct indicate two reconstructionrepair episodes in A.D. 340 ± 20 and A.D. 720 ± 20. The combined analysis of trench results; successive building and repair of aqueduct wall; and tufa onsets, growths, and interruptions suggests the occurrence of four faulting events in the last ∼3500 yr, with a cluster of three events in A.D. 160-510, A.D. 625-690, and A.D. 1010-1210, the latter being correlated with the 29 June 1170 large earthquake. Our study provides the timing of late Holocene earthquakes and infers a lower and upper bound of 4.9-6.3 mm/yr slip rate along the Missyaf segment of the Dead Sea fault in Syria. The inferred successive faulting events, fault segment length, and related amount of coseismic slip yield Mw = 7.3-7.5 for individual earthquakes. The identification of the temporal cluster of large seismic events suggests periods of seismic quiescence reaching 1700 yr along the Missyaf fault segment.

Seismic Hazard Assessment of the Lebanese Restraining Bend: A Neo-deterministic Approach

Article

Full-text available

Feb 2023
PURE APPL GEOPHYS

The Lebanese Restraining Bend is an active bend along the Dead Sea Transform Fault in the eastern Mediterranean region where several destructive earthquakes have occurred throughout history. In this paper, we assess the gross features of the seismic hazard of the Lebanese Restraining Bend by applying a neo-deterministic method that involves the generation of synthetic seismograms distributed on a regular grid over the study area. We use the regional seismicity, seismic source zones, focal mechanism solutions, and velocity structural models. We present maps of ground displacement, velocity, and acceleration. This is the first study that generates neo-deterministic seismic hazard maps for the Lebanese Restraining Bend using representative ground motion modeling. Our results show that displacement values of 15–30 cm and velocity values of 30–60 cm/s can be expected along most of Lebanon. In addition, 0.15–0.30 g acceleration values can dominate most of the Lebanese territory and surrounding areas. It is evident from these results that the study area in general and Lebanon in particular constitute a high seismic hazard area, which necessitates further attention from the authorities regarding the precaution measures needed to mitigate the effects of potential catastrophic seismic events; in addition, more detailed investigations are needed at local scale for specific sites of interest.

Estimating urban seismic damages and debris at the building-level: Application to the city of Beirut, Lebanon

Preprint

Full-text available

Dec 2022

The estimation of seismic damages and debris at the urban scale - at a precise building-by-building level- is challenging for several reasons. First, commonly used methodologies for seismic damage estimation rarely take into account the local site effects, precisely at the building-level. Second, the available methods for debris estimation fail to estimate at the same time the quantity of debris generated per building according to its damage level and the distribution of the debris (extent and height) around buildings. Finally, the lack of comprehensive data on the building stock and the relevant building properties and their taxonomy further increases the complexity of assessing possible earthquake consequences at an urban scale. This paper addresses these challenges and proposes improvements to the assessment of seismic damages and debris at the building level, along with the development of a 3D building model based on satellite images and heterogeneous data. These developments, applied to the city of Beirut, Lebanon, highlight the control of the site effects on the seismic damage spatial distribution throughout the city and the large volume and extent of debris to be expected in the city for a strong earthquake.

Salt-detached strike-slip faulting, Outer Kwanza Basin, Offshore Angola

Preprint

Full-text available

May 2022

We here use a 3D seismic reflection dataset from Outer Kwanza Basin, offshore Angola to examine the structure and growth of salt-detached strike-slip faults. The faults occur in four, up to 13.8 km-long, NE-trending arrays that are physically linked by restraining bend and releasing stepovers, and which presently overlie Aptian salt and base-salt relief related to pre-salt faulting. We suggest that these faults formed to accommodate along-margin variations in the rate and magnitude of differential seaward translation and salt diapirism, which commenced in the Early Cretaceous. We illustrate that the arrays grew by tip propagation of isolated fault segments, some of which linked during the Albian-Cenomanian (i.e., 113-100.5 Ma, or the initial 11-13% of their deformation history). Some arrays then reached their near-final length within the subsequent ca. 77 Ma, or the next 69-81% of their deformation history), while others attained this later, during the subsequent ca. 18 Ma (i.e., after 95% of their deformation history). During this time, the segments formed and then breached releasing and restraining stepovers, with the arrays as a whole growing by alternating periods of lengthening, throw accumulation, and inactivity. Our results also show that scatter in the D-L scaling of strike-slip faults reflect the propagation, interaction, and linkage of individual segments.

Reconstructing the slip velocities of the 1202 and 1759 CE earthquakes based on faulted archaeological structures at Tell Ateret, Dead Sea Fault

Article

Full-text available

Aug 2021
J SEISMOL

Archaeological structures built across active faults and ruptured by earthquakes have been used as markers to measure the amount of displacement caused by ground motion and thus to estimate the magnitude of ancient earthquakes. The example used in this study is the Crusader fortress at Tel Ateret (Vadum Iacob) in the Jordan Gorge, north of the Sea of Galilee, a site which has been ruptured repeatedly since the Iron Age. We use detailed laser scans and discrete element models of the fortification walls to deduce the slip velocity during the earthquake. Further, we test whether the in-situ observed deformation pattern of the walls allows quantifi-cation of the amount both sides of the fault moved and whether post-seismic creep contributed to total displacement. The dynamic simulation of the reaction of the fortification wall to a variety of earthquake scenarios supports the hypothesis that the wall was ruptured by two earthquakes in 1202 and 1759 CE. For the first time, we can estimate the slip velocity during the earthquakes to 3 and 1 m/s for the two events, attribute the main motion to the Arabian plate with a mostly locked Sinai plate, and exclude significant creep contribution to the observed displacements of 1.25 and 0.5 m, respectively. Considering a minimum long-term slip rate at the site of 2.6 mm/year, there is a deficit of at least 1.6 m slip corresponding to a potential future magnitude 7.5 earthquake ; if we assume~5 mm/year geodetic rate, the deficit is even larger.

The Beirut Port Explosion: A Geoscience Perspective

Article

Apr 2021

Tony Nemer

Fragmentation of the Sinai Plate indicated by spatial variation in present-day slip rate along the Dead Sea Fault System

Article

Feb 2020
GEOPHYS J INT

SUMMARY A comprehensive GPS velocity field along the Dead Sea Fault System (DSFS) provides new constraints on along-strike variations of near-transform crustal deformation along this plate boundary, and internal deformation of the Sinai and Arabian plates. In general, geodetically-derived slip rates decrease northward along the transform (5.0 ± 0.2–2.2 ± 0.5 mm yr−1), and are consistent with geological slip rates averaged over longer time periods. Localized reductions in slip rate occur where the Sinai plate is in ∼N-S extension. Extension is confined to the Sinai side of the fault, is associated with prominent changes in transform geometry, and with NW-SE striking, left-lateral splay faults, including the Carmel fault in Israel and the Roum fault in Lebanon. The asymmetry of the extensional velocity gradients about the transform reflects active fragmentation of the Sinai plate along the continental margin. Additionally, elastic block modeling of GPS velocities requires an additional structure off-shore the northern DSF segment, that may correspond with a fault located along the continental margin, suggested by prior geophysical studies.

An updated parametric catalog of historical earthquakes around the Dead Sea Transform Fault Zone

Article

Full-text available

Aug 2020
J SEISMOL

In this study we present the work done to review the existing historical earthquake information of the Dead Sea Transform Fault Zone (DSTFZ). Several studies from various sources have been collected and reassessed, with the ultimate goal of creating of new homogenized parametric earthquake catalogue for the region. We analyze 244 earthquakes between 31BC and 1900, which are associated with the geographical buffer extending from 27N to 36N and from 31E to 39E. Of these, 93 were considered real seismic events with moment magnitude (Mw) greater than 5 that indeed occured within this zone. While we relied on past parametric data and did not assign new macroseismic intensities, magnitude values or epicenters for several controversial events, we did however resort to the primary sources to obtain a more critical perspective for the various assigned macroseismic intensities. In order to validate the derived parametric information, we tried to associate the events present in the historical records, with any evidence coming from past field investigations, i.e. geological or archaeological studies. Acknowledging the uneven quality and quantity of data reporting each event, we provided each entry with an uncertainty range estimate. Our catalog lists 33 events of Mw≥6 absent from the latest published compilation with compatible time span and areal coverage. The whole catalog is considered complete down to Mw 7 and in certain areas down to Mw 6 after the year 1000, with majority of the larger earthquakes located in the part of DSTFZ, which extends from the southeast part of Dead Sea lake till Antioch.

Supplemental material - Temporal and spatial patterns of seismic activity associated with the Dead Sea Transform (DST) during the past 3000 years

Data

Full-text available

Oct 2019

Motti Zohar

The supplemental material contains the data used in the paper. It includes 3 tables: (1) Table S1: list of reliable events associated with DST activity; (2) Table S2: list of doubtful events associated with DST activity; and (3) Table S3: reliable events that affected or damaged regions close to the DST but their MRDZ (Most Reported Damage Zone) is far off any of the DST zones thus implying, most likely, on off-DST seismic activity. Abbreviations used in Tables S1, S2 and S3 appear at the end of the file

Temporal and Spatial Patterns of Seismic Activity Associated with the Dead Sea Transform (DST) during the Past 3000 Yr

Article

Oct 2019

Motti Zohar

Historical reports of earthquakes occurring before the twentieth century along the Dead Sea Transform (DST) are available for the past 3000 yr. Most of them are organized in various catalogs, reappraisals, and lists. Using a comprehensive and consistent compilation of these reports, the historical seismicity associated with the DST as a complete tectonic unit was examined. The compilation, supported by paleoseismic and archeoseismic evidence, resulted in 174 reliable historical earthquakes and 112 doubtful ones. The reliable earthquakes, along with 42 post‐nineteenth century instrumental earthquakes, are an up‐to‐date evaluation of the DST seismicity starting from the mid‐eighth century B.C.E. until 2015 C.E. Additionally, the scenario of historical earthquakes such as the 363 C.E. and 1033 C.E. events was resolved. The characterization of temporal and spatial patterns of DST seismicity, classifying them into four geographical zones, raised that most of the northern destructive earthquakes are clustered while clustering at the central and southern zones is less abundant.

Assessment of potential seismic hazard for sensitive facilities by applying seismo-tectonic criteria: an example from the Levant region

Article

Full-text available

May 2019

We present a methodology for mapping faults that constitute a potential hazard to structures, with an emphasis on special facilities such as dams and nuclear power plants. The methodology categorises faults by hierarchical seismo-tectonic criteria, which are designed according to the degree of certainty for recent activity and the accessibility of the information within a given region. First, the instrumental seismicity is statistically processed to obtain the gridded seismicity of the earthquake density and the seismic moment density parameters. Their spatial distribution reveals the zones of the seismic sources, within the examined period. We combine these results with geodetic slip rates, historical earthquake data, geological maps and other sources to define and categorise faults that are likely to generate significant earthquakes (M ≥ 6.0). Their mapping is fundamental for seismo-tectonic modelling and for PSHA analyses. In addition, for surface rupture hazard, we create a database and a map of capable faults, by developing criteria according to the regional stratigraphy and the seismotectonic configuration. The relationship between seismicity slip dynamics and fault activity through time is an intrinsic result of our analysis that allows revealing the tectonic evolution of a given region. The presented methodology expands the ability to differentiate between subgroups for planning or maintenance of different constructions or for research aims, and can be applied in other regions.

Estimation of Near-Fault Strong Ground-Motion

Thesis

Full-text available

Oct 2018

Rosemary Fayjaloun

Accumulated data of strong ground motions have been providing us very important knowledge about rupture processes of earthquakes, propagation-path, site-amplification effects on ground motion, the relation between ground motion and damage... However, most of the ground motion databases used in the development of ground motion prediction models are primarily comprised of accelerograms produced by small and moderate earthquakes. Hence, as magnitude increases, the sets of ground motions become sparse. Ground motion databases are poorly sampled for short source-to-site distance ranges (‘Near-fault’ ranges). However, the strongest ground shaking generally occurs close to earthquake fault rupture. Countries of moderate to high seismicity for which major faults can break in the vicinity of its major cities are facing a major seismic risk, but the lack of earthquake recordings makes it difficult to predict ground motion. Strong motion simulations may then be used instead. One of the current challenges for seismologists is the development of reliable methods for simulating near-fault ground motion taking into account the lack of knowledge about the characteristics of a potential rupture. This thesis is divided into 2 parts. Part 1 focuses on better understanding the seismic rupture process and its relation with the near-fault ground motion. The mechanisms of peak ground motion generating are investigated for homogeneous as well as for heterogeneous ruptures. A quantitative sensitivity analysis of the ground motion to the source kinematic parameters is presented, for sites located in the vicinity of the fault rupture, as well as far from the rupture. A second chapter is dedicated to a major near-fault source effect: the directivity effect. This phenomenon happens when the rupture propagates towards a site of interest, with a rupture speed close to the shear-wave speed (Vs); the waves propagating towards the site adds up constructively and generates a large amplitude wave called the pulse. The features of this pulse are of interest for the earthquake engineering community. In this chapter, a simple equation is presented that relates the period of the pulse to the geometric configuration of the rupture and the site of interest, and to the source parameters.Part 2 is dedicated to better estimate the seismic hazard in Lebanon by simulating the strong ground motion at sites near the main fault (the Yammouneh fault). Lebanon is located in an active tectonic environment where the seismic hazard is considered moderate to high. Historically, destructive earthquakes occurred in the past, the last one dates back to 1202. However, strong motion has never been recorded in Lebanon till now due to the presently infrequent large-magnitude seismicity, and therefore facing an alarming note of potential new ruptures. The Yammouneh fault is a large strike-slip fault crossing Lebanon, making all its regions located within 25km away from the fault. At first, the crustal structure tomography of Lebanon, in terms of Vs, is performed using the ambient noise, in order to characterise the wave propagation from the rupture to the ground surface. To our knowledge, this is the first study of the 3D Vs tomography in Lebanon. Afterwards, a hybrid approach is presented to simulate broadband near-fault ground motion . At low-frequencies (≤1Hz), potential ruptures of M7 are simulated (as defined in the previous chapters), and the generated slip rate functions are convolved with the Green’s functions computed for the propagation medium defined by the Vs tomography. The ground-motion is complemented by a high-frequency content (up to 10Hz), using a stochastic model calibrated by near-fault recordings and accounting for the presence of the directivity pulse. The computed peak ground acceleration is compared to the design acceleration in Lebanon.

Seismicity assessment in and around Syria based on instrumental data: application of Gumbel distributions and Gutenberg-Richter relationship

Article

Full-text available

Jan 2017

An instrumental earthquake catalog covering the time span between 1903 and 2007 and for the area bounded by 32°N–38°N and 35°E–43°E has been compiled in this research. The catalog has a magnitude of completeness (Mc) with 3.5. Least squares and statistical probability Gumbel’s techniques with different approaches have been applied on the instrumental events in order to assess the average recurrence time periods for different earthquake magnitudes. The constants a and b of Gutenberg-Richter and the average recurrence times have been computed firstly for the study area and secondly for the central and northern parts of Dead Sea fault system. The different statistical computations using Knopoff and Kagan formalism are generally in agreement and suggest an average recurrence time of 203 years for an earthquake of magnitude 7 for the region. The occurrence of large welldocumented historical earthquakes in Lebanon and western Syria, the existence of active fault segments, the absence of large earthquakes during the study period, the increasing number of the low-magnitude earthquakes, and the continued accumulation of the strain since 1900 indicate therefore the probability of an earthquake occurrence of a large magnitude. This should be permanently taken into consideration in seismic hazard assessment on the local and regional scales.

Towards a microzonation of the Greater Beirut area: an instrumental approach combining earthquake and ambient vibration recordings

Article

Full-text available

Dec 2018
B EARTHQ ENG

Lebanon is situated on the 1000 km long Levant transform fault that separates the Arabic from the African tectonic plates. In Lebanon, the Levant fault splits up into a set of ramifications that had, in the past, generated major destructive earthquakes causing a lot of destruction and thousands of casualties. The most devastating one was the 551 A.D. offshore earthquake that destroyed Beirut, the capital of Lebanon. This paper presents a site effect study in Beirut, aimed at proposing a framework for future microzonation works in the city. It includes two complementary parts. A 6-month, temporary seismological experiment was first conducted to estimate the site response at 10 sites sampling the main geological units of Beirut on the basis of local and regional earthquake recordings. This spatially sparse information was then complemented by a large number (615) of microtremor measurements covering the Beirut municipality and part of its suburbs with a 400 m dense grid. The recordings were analysed with the standard site-to-reference and horizontal-to-vertical spectral ratio methods for earthquake recordings, and the horizontal-to-vertical ratio for ambient noise recordings. Significant ground motion amplification effects (up to a factor of 8) are found in a few areas corresponding to recent deposits. The consistency between results from earthquake and microtremor recordings allows proposing a map of the resonance frequencies within the city and its suburbs, with frequencies ranging from 0.5 to 5 Hz for the deepest deposits, and 5–10 Hz for shallow areas. Finally, the results are discussed and a way to combine the results obtained from the temporary stations to the great number of recordings coming from the permanent Lebanese network is proposed.

The Ruin of the Roman Temple of Kedesh, Israel; Example of a Precariously Balanced Archaeological Structure Used as a Seismoscope

Article

Full-text available

Jul 2017

In certain regions and under favorable geologic conditions, precariously balanced rocks may form. These types of unusual formations have been used to estimate yield ground motions. Because such balanced rocks have not been 'unbalanced', they can be used as a rough estimate for ground motions which have not been reached or exceeded since the balanced formation achieved its contemporary state. We hypothesize that other ancient manmade structures, delicate in terms of stability and particularly those that have survived earthquake ground motions intact, can be used in the same manner. We therefore suggest that these structures act as local seismoscopes which might be capable of determining maximum upper ground motion bounds. We apply the concept of the study of precariously balanced rocks to the ruin of the Roman Temple of Kedesh, located in close proximity to a branch of the Dead Sea Transform Fault. The delicate-looking ruin was surveyed with a 3D laser scanner. Based on the point cloud from that survey, a discrete element model of the remaining temple wall was constructed. To test the stability of the model we used 54 analytical ground motion signals with frequencies ranging from 0.3 to 2 Hz and PGAs between 1 and 9 m/s 2. These calculations reveal two failure mechanisms. Additionally, ground motions of eight earthquakes, including two assumed local earthquake scenarios, five historical earthquakes of the region and one strong motion record of the 1999 Taiwan Chi Chi earthquake have been used to test the hypothesis. None of the simulated earthquakes (assumed or historically documented) toppled the ruin; only the strong motion record collapsed the structure. The simulations reveal a surprisingly high stability of the ruin of the Roman Temple of Kedesh mainly due to the small height to width ratio of the remaining walls. However, ground motion with large PGAs at a low frequency range in EW direction does collapse the remains of the temple.

Damage patterns of past earthquakes in Israel – Preliminary Evaluation of historical sources

Technical Report

Nov 2013

We collect and compile the information associated with damaging events that occurred from the second millennia BCE to the instrumental 1927 CE Jericho earthquake. The compilation results three lists: (1) Confirmed events associated with DST activity that affected Israel and its surroundings; (2) Questionable events and (3) Confirmed events associated with neighboring tectonic sources off the DST. We focus on the events of the first list and inspect their temporal and spatial damage distribution. Accordingly, we roughly estimate their size and evaluate the completeness of the list. What emerges from the lists is that (1) Israel was struck by a damaging earthquake about 31 times during the last two millennia, that is once in about 65 years on the average, although not regularly; (2) damaging events originated from north of Israel tend to be more destructive than those within Israel; (3) the damage resulting by those northern and central events seem to decrease almost completely south of northern Dead Sea but this may also reflect the decrease of population towards the south and (4) localities within Transjordan were not necessarily less damaged but probably reports are just lacking.

Supplementary material - Reappraised list of historical earthquakes that affected Israel and its close surroundings

Data

Full-text available

Apr 2016

Lateral Motion and Deformation Along the Dead Sea Transform

Chapter

May 2014

Zvi Garfunkel

This paper presents an updated summary of the history and shallow structure of the Dead Sea transform (DST) and its plate tectonic context. The DST formed in the Early Miocene as a transform boundary between the Sinai and Arabian plates. The lateral offset was ca. 105 km near the Dead Sea. Since the DST trace is irregular in map view, the lateral motion led to formation of a 10–80 km wide deformation zone along the plate junction. Thus, the structures along the DST can be interpreted within the framework of the Sinai-Arabia plate kinematics. South of ca. lat. 33° transtension, which increased with time, led to variable oblique separation of the plate edges. This produced an almost continuous ca. 5–25 km wide depression whose structure is dominated by a string of pull-apart basins up to 15–20 km wide and up to ca. 12 km deep. The crystalline crust under the largest basins was appreciably thinned and may have been intruded by basalts. The structural pattern changed over time, the present pattern having been mostly established in the second half of the DST history. North of lat. ca. 33°N transpression dominates and the DST flanks are strongly deformed by folding, faulting, and rotation of fault blocks on vertical axes, which together produce shortening perpendicular to the DST and also left lateral shearing of its flanks, qualitatively compatible with the plate kinematic. The deformation can also account for the observed decrease of the lateral offset along the main fault line from ca. 100 km at ca. lat 33°N to 65–70 km at lat. 36°–36.5°N, and also leads to left lateral shearing along the continental margin near the Galilee and farther north. North of lat. 36.5°N the DST now interacts with the Anatolian plate and the Cyprus arc. This resulted from a rearrangement of the plate configuration in that region when westward extrusion of Anatolia began and the East Anatolian Fault formed, but the details of the kinematic changes are incompletely known. This change obscured the structural relations in this region during the early stages of the DST history.

Why is the minaret so short? evidence for earthquake damage on Mt Zion

Article

Aug 2015

On top of King David's Sepulchre at Mt Zion there is an Ottoman minaret known as al-Nabi Da'ud. Compared with other minarets in Jerusalem, al-Nabi Da'ud seems to be somewhat shorter, and has a squat-like appearance. To track why it is shorter than other minarets, we inspected written historical sources, a sequence of old drawings dated between the mid-eighteenth and mid-nineteenth centuries and analysed the minaret's metric proportions. In drawings dated to and before 1833, the minaret is portrayed much higher than in drawings and photographs dated to and after 1838. Furthermore, comparative height-diameter ratio of various parts of the minaret does not fit those of its counterpart, the al-Qal'a minaret. Thus, we suggest that the minaret was originally built higher but damaged during the 1834 earthquake, and reconstructed to a lower height sometimes afterwards.

Active tectonics along the Wadi Araba-Jordan Valley transform fault

Article

Full-text available

Dec 2018

Paolo Galli

A geological study has been carried out along the 200 km long Wadi Araba following the transform fault that separates the Arabian and Sinai-African Plates. Recent movements along this structure affect upper Pleistocene-Holocene deposits and archaeological sites. Kinematic indicators show sinistral strike-slip and oblique movements, in agreement with the relative motion between the two plates. Other evidence of recent horizontal displacement exists along the Jordan Valley Fault, both on the Dead Sea-Lake Tiberias segment and on the segment north of Lake Tiberias. A minimum horizontal slip rate of 1 cm yr-• has been estimated for both the southern segment of the Wadi Araba Fault and for the southern Jordan River Fault. The two faults can be roughly subdivided into at least four segments: two in the Wadi Araba (80 km long each), one from the Dead Sea to Lake Tiberias (130 km), and one from Lake Tiberias to the Hula graben (>30 km). Faulting may also occur along shorter subsegments, as shown by bends in the Wadi Araba-Jordan River Fault and by the growth of local compression and extension features. Instrument-recorded seismicity appears to be mainly concentrated along some of these subsegments. A comparison between the observed seismic and field-determined slip rates across the fault indicates possible strain accumulation during the last 2000 years.

Crusader castle torn apart by earthquake at dawn, 20 May 1202

Article

Full-text available

Apr 1998
GEOLOGY

The Crusader castle of Vadum Jacob, an outpost overlooking the Jordan River, was deformed during a destructive earthquake triggered by motion along the Dead Sea Transform. The M >7 earthquake occurred at dawn, 20 May 1202, and offset the castle walls by 1.6 m. This exceptional precision in dating and estimating displacement was achieved by combining accounts from primary historical sources, by excavating the Dead Sea Transform where it bisects the castle, and by dating faulted archaeological strata. The earthquakes of October 1759 and/or January 1837 may account for the remaining 0.5 m out of a total 2.1 m of offset. Our study exploits the potential embodied in interdisciplinary historical-archaeological-geological research and illustrates how detailed histories of seismogenic faults can be reconstructed.

Geomorphology and seismicity of the Roum Fault as one of the active branches of the Dead Sea Fault System in Lebanon

Article

Full-text available

Mar 2001

Kamal Khair

To the south of Lebanon the Dead Sea Transform fault has a well-documented left-lateral displacement of about 105 km. In Lebanon, most of the movement is taken up by several major and minor faults. These are the NNE trending Yammouneh, and its NE branch Mid-Beqa'a, Serghaya, Rachaya, and Hasbaya faults, and the NNW trending Roum fault. Geophysical, geomorphological, and geological study of the Roum fault zone and its northern extension in the Chouf area has led to the following conclusions: (1) The sinistral displacement along the Roum fault, as reflected by the offset of drainage patterns, decreases northward from 8.5 km across the Litani river to ~1 km across the Awali river. (2) In the Chouf area the lateral displacement is dispersed into a complex network of faults and fractures reflected by clearly pronounced lineaments and therefore is not entirely transmitted northward. (3) The seismicity of the Roum fault zone and the Chouf area is characterized by earthquakes of moderate magnitude with a release interval of 40-50 years. (4) The seismicity of Lebanon, in general, is characterized by strong earthquakes with very long recurrence interval. (5) The bifurcation of the Dead Sea transform fault into several faults in Lebanon has probably occurred in response to the clockwise rotation of the upper part of its crust. (6) In the future ``geologic time'' the Roum fault will, probably, take up more of the offset, while the significance of other fault branches will decline.

The 9 July 551 AD Beirut earthquake, Eastern Mediterranean Region

Article

Full-text available

Oct 2000
J EARTHQ ENG

Analysis of the Byzantine primary and secondary sources for identifying the historical earthquakes in Syria and Lebanon reveals that a large earthquake (M s =7.2) occurred in July 9, 551 AD along the Lebanese littoral and was felt over a very large area in the eastern Mediterranean region. It was a shallow-focus earthquake, associated with a regional tsunami along the Lebanese coast, a local landslide near Al-Batron town, and a large fire in Beirut. It caused heavy destruction with great loss of lives to several Lebanese cities, mainly Beirut, with a maximum intensity between IX-X (EMS-92). The proposed epicentre of the event is offshore of Beirut at about 34.00°N, 35.50° E, indicating that the earthquake appears to be the result of movement along the strike-slip left-lateral Roum fault in southern Lebanon.

The Surface Rupture and Slip Distribution of the 17 August 1999 Izmit Earthquake (M 7.4), North Anatolian Fault

Article

Full-text available

Feb 2002

The 17 August 1999 Izmit earthquake occurred on the northern strand of the North Anatolian fault zone. The earthquake is associated with a 145-km-long surface rupture that extends from southwest of Duzce in the east to west of Hersek delta in the west. Detailed mapping of the surface rupture shows that it consists of five segments separated by releasing step-overs; herein named the Hersek, Karamursel–Golcuk, Izmit–Sapanca Lake, Sapanca–Akyazi, and Karadere segments from west to east, respectively. The Hersek segment, which cuts the tip of a large delta plain in the western end of the rupture zone, has an orientation of N80�. The N70�–80�E–trending Karamu¨rsel–Go¨lcu¨k segment extends along the linear southern coasts of the Izmit Gulf between Karamursel and Golcuk and produced the 470-cm maximum displacement in Golcuk. The northwest–southeast-striking Golcuk normal fault between the Karamursel–Golcuk and I˙zmit–Sapanca segments has 2.3-m maximum vertical displacement. The maximum dextral offset along the Izmit–Sapanca Lake segment was measured to be about 3.5 m, and its trend varies between N80�E and east–west. The Sapanca–Akyazi segment trends N75�–85�W and expresses a maximum displacement of 5.2 m. The Karadere segment trends N65�E and produced up to 1.5-m maximum displacement. The Karadere and Sapanca–Akyazi segments form fan-shape or splaying ruptures near their eastern ends where the displacement also diminished.

Radiocarbon Calibration and Analysis of Stratigraphy: The OxCal Program

Conference Paper

Full-text available

Jan 1995
RADIOCARBON

Christopher Bronk Ramsey

People usually study the chronologies of archaeological sites and geological sequences using many different kinds of evidence, taking into account calibrated radiocarbon dates, other dating methods and stratigraphic information. Many individual case studies demonstrate the value of using statistical methods to combine these different types of information. I have developed a computer program, OxCal, running under Windows 3.1 (for IBM PCs), that will perform both C-14 calibration and calculate what extra information can be gained from stratigraphic evidence. The program can perform automatic wiggle matches and calculate probability distributions for samples in sequences and phases. The program is written in C++ and uses Bayesian statistics and Gibbs sampling for the calculations. The program is very easy to use, both for simple calibration and complex site analysis, and will produce graphical output from virtually any printer.

New Empirical Relationships among Magnitude, Rupture Length, Rupture Width, Rupture Area, and Surface Displacement

Article

Full-text available

Aug 1994

Source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude (M), surface rupture length, subsurface rupture length, downdip rupture width, rupture area, and maximum and average displacement per event. The resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment, moment magnitude, subsurface rupture length, downdip rupture width, and average surface displacement. Each source parameter is classified as reliable or unreliable, based on our evaluation of the accuracy of individual values. Only the reliable source parameters are used in the final analyses. In comparing source parameters, we note the following trends: (1) Generally, the length of rupture at the surface is equal to 75% of the subsurface rupture length; however, the ratio of surface rupture length to subsurface rupture length increases with magnitude; (2) the average surface displacement per

The earthquake of 1 January 1837 in Southern Lebanon and N orthern Israel

Article

Full-text available

Jun 1997

N. N. Ambraseys

All of our 20th-century information for the Levant Fracture and Dead Sea transform fault systems is for a qui- escent period in the seismicity. This is apparent when we consider earlier events which show that infi.equent earthquakes have occurred in the past along this system, an important consideration for the assessment of haz- ard and tectonics of the Middle East. One of these events was the earthquake of 1837 which caused heavy damage in Northem Israel and Southem Lebanon. This earthquake was a much larger event than earthquake catalogues indicate. We reckon it was a shallow, probably multiple event of magnitude greater than 7.0.

The Historical Earthquakes of Syria: An Analysis of Large and Moderate Earthquakes from 1365 B.C. to 1900 A.D

Article

Full-text available

Jun 2005

The historical sources of large and moderate earthquakes, earthquake catalogues and monographs exist in many depositories in Syria and European centers. They have been studied, and the detailed review and analysis resulted in a catalogue with 181 historical earthquakes from 1365 B.C. to 1900 A.D. Numerous original documents in Arabic, Latin, Byzantine and Assyrian allowed us to identify seismic events not mentioned in previous works. In particular, detailed descriptions of damage in Arabic sources provided quantitative information necessary to re-evaluate past seismic events. These large earthquakes (I0>VIII) caused considerable damage in cities, towns and villages located along the northern section of the Dead Sea fault system. Fewer large events also occurred along the Palmyra, Ar-Rassafeh and the Euphrates faults in Eastern Syria. Descriptions in original sources document foreshocks, aftershocks, fault ruptures, liquefaction, landslides, tsunamis, fires and other damages. We present here an updated historical catalogue of 181 historical earthquakes distributed in 4 categories regarding the originality and other considerations, we also present a table of the parametric catalogue of 36 historical earthquakes (table I) and a table of the complete list of all historical earthquakes (181 events) with the affected locality names and parameters of information quality and completeness (table II) using methods already applied in other regions (Italy, England, Iran, Russia) with a completeness test using EMS-92. This test suggests that the catalogue is relatively complete for magnitudes >6.5. This catalogue may contribute to a comprehensive and unified parametric earthquake catalogue and to a realistic assessment of seismic hazards in Syria and surrounding regions.

The structural and geomorphic evolution of the Dead Sea rift

Article

Jan 1956

A.M. Quennell

Radiocarbon calibration and analysis of stratigraphy: The OxCal program

Article

Jan 1995
RADIOCARBON

Christopher Bronk Ramsey

Radiocarbon Calibration and Analysis of Stratigraphy: The OxCal Program

Article

Jan 1995
RADIOCARBON

Christopher Bronk Ramsey

People usually study the chronologies of archaeological sites and geological sequences using many different kinds of evidence, taking into account calibrated radiocarbon dates, other dating methods and stratigraphic information. Many individual case studies demonstrate the value of using statistical methods to combine these different types of information. I have developed a computer program, OxCal, running under Windows 3.1 (for IBM PCs), that will perform both 14 C calibration and calculate what extra information can be gained from stratigraphic evidence. The program can perform automatic wiggle matches and calculate probability distributions for samples in sequences and phases. The program is written in C++ and uses Bayesian statistics and Gibbs sampling for the calculations. The program is very easy to use, both for simple calibration and complex site analysis, and will produce graphical output from virtually any printer.

Seismic reflection structure of intracratonic Palmyride fold-thrust belt and surrounding Arabian platform, Syria

Article

Jan 1990
AAPG BULL

John H. Mcbride

Seismic reflection and drill-hole data from central Syria provide a detailed view of the subsurface structure (10-15 km depth) of the relatively little-studied intracratonic Palymride fold and thrust belt. The seismic reflection and drill-hole data show Mesozoic stratigraphic sequences thickening abruptly into the Palmyrides from the adjacent, arched Paleozoic platforms. Neogene (Alpine) folding and thrusting of the Mesozoic basin, as documented on the seismic data, are sharply restricted to the narrow width of the belt (~100 km), in contrast to the relatively undeformed Phanerozoic strata of the platforms to the north and south. The seismic and drill-hole data support the hypothesis that the Palmyrides began as a Permian-Triassic failed rift connected to the Levantine passive continental margin, which was inverted and complexly deformed by the interfering effects of Cenozoic movements along the Dea Sea transform fault system and the Turkish Bitlis convergent zone. -from Authors

High-resolution radiocarbon age calibration for terrestrial and marine samples

Article

Jan 1993
RADIOCARBON

Historical seismicity in the Near and Middle East, North Africa, and Spain from Arabic documents (VIIth-XVIIIth century)

Article

Dec 1980

A catalog of historical seismicity from the VIIth to the XVIIIth century A.D. was compiled from Arabic documents (many of which are unpublished manuscripts) for the near and Middle East, and in a lesser measure, for North Africa and Spain. In most cases, detailed descriptions have allowed us to assign Modified Mercalli intensities to the shocks for the localities where they were reported. The detailed chronology of a protracted episode of seismicity in northern Syria between 1156 and 1159 is given shock by shock from the relation of a Damascus chronicler.

The Seismicity of Egypt, Arabia and the Red Sea

Article

Jan 1995

This book provides a catalog of earthquakes that have occurred in Egypt, Arabia, the Red Sea region, and the surrounding areas of Libya, Sudan, and Ethiopia from the earliest times (184 BC) to the present day. By careful and intensive study of historical sources and a review of the instrumental data of this century, the authors describe each earthquake as fully as possible and analyze each in a geographical and historical context. They further scrutinize the completeness of the earthquake catalog over time and examine the range of sources and the problems associated with such historical records.

Extended 14C data base and revised CALIB 3.0 14C age calibration program

Article

Jan 1993
RADIOCARBON

The Age Calibration Program, CALIB, published in 1986 and amended in 1987 is here amended anew. The program is available on a floppy disk in this publication. The new calibration data set covers nearly 22 000 Cal yr (approx 18 400 14C yr) and represents a 6 yr timescale calibration effort by several laboratories. The data are described and the program outlined. -K.Clayton

Surface Rupture and Slip Distribution of the 12 November 1999 Duzce Earthquake (M 7.1), North Anatolian Fault, Bolu, Turkey

Article

Feb 2002

H. Serdar Akyuz

The 12 November 1999 earthquake ( M 7.1) occurred on the Duzce fault, a splay of the North Anatolian fault in the Bolu basin approximately three months after the 17 August 1999 ( M 7.4) earthquake. The surface rupture was 40 km long, and the maximum right-lateral offset was 500 ± 5 cm, averaging 300 cm. The 9 km of the westernmost part of the rupture along the southern margin of the Eften Lake had a 350-cm maximum vertical displacement (normal faulting), some of which was already ruptured during the 17 August 1999 event with few tens of centimeters. The surface rupture has a generally simple narrow deformation zone of 0.5-5 m, however, in some places, it widens to 50 m. Transtensional and transpressional structures were observed within releasing and restraining step-over areas respectively. The larger dextral offsets on some streams indicate previous events. The dextral slip measurements along the rupture reflect a symmetric distribution. The eastern connection of this rupture zone with the main trace of North Anatolian fault remains unclear because the Bakacak and Elmalik fault, which are connecting faults, had no surface rupture. Manuscript received 14 November 2000.

The structural response to evolving plate kinematics during transpression: evolution of the Lebanese restraining bend of the Dead Sea Transform

Article

Jan 1998

This paper is part of the special publication Continental transpressional and transtensional tectonics (eds R.E. Holdsworth, R.A. Strachan and J.F. Dewey). Structural evolution along continental transform faults may be related to fault zone geometry and to regional variations in plate kinematics. Using a case study of the Lebanese sector of the Dead Sea Transform, the finite geometry of transpression at a restraining bend can be shown to have evolved in time. Relative structural chronologies, calibrated against dated landscape features such as lava-covered palaeosurfaces, coastal erosion surfaces and their incised drainage basins, are used to establish the timing of displacement activity on the major transcurrent faults. The early part of the region's structural history, up to late Miocene times, was controlled by the geometry of the through-going Yammouneh Fault. Transpression on this right-trending left-lateral structure was accommodated by strike-slip and distributed crustal shortening represented by the initial uplift of Mount Lebanon. For the past 6 Ma the principal active strand of the transform has been the Roum Fault. For much of this period it is presumed to have been a through-going fault which accommodated about 30 km left-lateral displacement. During the Quaternary, the fault zone has become strongly segmented. Although the location of active transcurrent faulting has migrated during the history of the transform, the major site of crustal shortening, the Mount Lebanon-Jabel Barouk structure, has remained broadly fixed. However, the rates of amplification of this structure and the coastal flexure appear to have varied. Continuing uplift of Mount Lebanon and local Plio- Quaternary folding suggest that the offshore continuation of the Roum Fault contains a rightwards, transpressive bend. We relate this multistage history for the Lebanese sector of the transform to an evolving plate tectonic setting: the rotation pole for relative plate motion between Africa and Arabia has migrated through time and the triple junction between the transform and the Tethyan destructive plate margin to the north has moved from onshore SE Turkey to now lie in the NE Mediterranean. Our case study illustrates the transient and evolving nature of deformation in continental restraining beds.

Strain accommodation at the lateral margin of an active transpressive zone: Geological and seismological evidence from the Lebanese restraining bend

Article

Mar 2000

Geological, geomorphological, and seismological data are used to postulate the existence of a lateral domain‐bounding fault, the Roum fault zone in SW Lebanon. The fault zone accommodates transpression at the margins of the Lebanese restraining bend, abruptly dividing the transpressional Mount Lebanon (Jebel Barouk) uplift from the extension of the Tyre Nabatiye plateau. Transpressional deformation at the SW margin of the restraining bend is mainly seen through large scale folding trending parallel to the restraining bend. Such folding is thought to be accommodated laterally along a 100 km length of fault zone in SW Lebanon, the Roum fault zone. Mapped lineaments and topographic expression show the fault zone to die out to the south of Beirut. Offsets of incised river valleys decrease northwards from 7.2 km to 0.2 km along the length of the fault zone over a distance of 80 km, also inferring a postulated fault tip to the south of Beirut. Strain gradients along both sides of the fault zone wall rocks shows several deformation mechanisms to be involved; pressure solution, folding, distributed shear, and normal faulting. The postulated fault tip coincides with the extent of transpression of the Mount Lebanon block. A new seismicity catalogue (2100 BC–AD 1995: 32–35°N, 34–37°E: 1725 events: all magnitudes converted to ISN‐reported M L ) was compiled from published sources. Seismicity is apparently sparse around the northern Yammouneh fault but concentrates in SW Lebanon, especially in a diffuse 50–100 km wide zone around the southern Roum fault zone. Epicentral uncertainties are typically 10–25 km for modern reporting, although depths are poorly known. The seismic b‐value is 0.75 ± 0.07 for the Beirut area compared to 0.88 ± 0.09 for the Dead Sea transform to the south: mapping of b ‐values for the SW Lebanon area suggests a gradual reduction northward along the Roum fault zone. These observations are interpreted as the signature of a fault zone whose tip lies to the south of Beirut. The transition from transpression to extended crust, at the western edge of the Lebanese restraining bend, is accommodated along a 100 km length of fault zone. Decreasing seismic activity (over the time of the catalogue) and seismic b ‐values imply a differing style or mechanism of faulting in the short term along the Roum fault zone, toward Beirut.

Surface observations of active normal fault propagation: Implications for growth

Article

May 2002

Geomorphological, sedimentological and structural observations demonstrate the rates of lateral propagation at both ends of the South Alkyonides Fault, a major active normal fault in the Gulf of Corinth. Greece. These data are used to study the temporal evolution of the displacement/length ratio of the fault, The South Alkyonides Fault has a surface trace of 38 km and a Cumulative throw of 2.5-3.0 km. Palaeoseismology and geodesy show that the South Alkyonides Fault has a maximum displacement rate of 2.6-4.7 mm a(-1). Lateral propagation of the South Alkyonides Fault has systematically beheaded drainage, forming footwall wind gaps and enclosed hanging-wall basins. Dated marine and terrestrial sediments allow estimation of the timing of wind gap formation and rates of lateral propagation of the South Alkyonides Fault. The western and eastern ends of the South Alkyonides Fault have been propagating at 12.1-16.7 mm a(-1) since c.0.33 Ma and <3,7 mm a(-1) since 1,36 Ma, respectively. The summed rate of lateral propagation is 15.8-20.4 mm a(-1). The value for the ratio of displacement rate-to-lateral propagation rate (0.13-0.30) over the last several hundred thousand ears is higher than the ratio of cumulative displacement/length (0.07-0.12). Lateral propagation may hake slogged relative to the displacement rate through time.

Sources of the large A.D. 1202 and 1759 Near East earthquakes

Article

Jul 2005
GEOLOGY

The sources of the May 1202 and November 1759, M 7.5 Near East earthquakes remain controversial, because their macroseismal areas coincide, straddling subparallel active faults in the Lebanese restraining bend. Paleoseismic trenching in the Yammoûneh basin yields unambiguous evidence both for slip on the Yammoû neh fault in the twelfth thirteenth centuries and for the lack of a posterior event. This conclusion is supported by comparing the freshest visible fault scarps, which imply more recent slip on the Râchaïya-Serghaya system than on the Yammoûneh fault. Our results suggest that the recurrence of an A.D. 1202 type earthquake might be due this century, as part of a sequence similar to that of A.D. 1033 1202, possibly heralded by the occurrence of the 1995 Mw 7.3 Aqaba earthquake. The seismic behavior of the Levant fault might thus be characterized by millennial periods of quiescence, separated by clusters of large earthquakes.

Four Thousand Years of Seismicity Along the Dead Sea Rift

Article

Nov 1991

Ari Ben-Menahem

A study of major earthquake occurrence along the Dead Sea transform (35.5°–36.5° E; 27.2°–37.5° N) during the past four millenia has been attempted. Geological, archaeological, biblical, historical, and seismological evidence were integrated in an effort to quantify the space-time distribution of seismicity in the said province. The overall earthquake activity in the conterminous Near East indicates a stable pattern and appeared to have been stationary over the examined time window. About 110 earthquakes in the magnitude range 6.7 ≤ ML ≤ 8.3 affected the area during the past 2500 years. Of these, 42 originated along the Dead Sea fault system itself, while 68 were imported from the Helenic-Cyprian arcs and the Anatolian-Elburz-Zagros fault systems. These events were responsible for the repeated destruction of many cultural centers. In the Dead Sea region proper, the major seismic activity since 2100 B.C.E. (Before Christian Era), has been confined to the vicinity of its eastern shore with extremal seismicity at its southern tip near the prehistorical site of Bab-a-Dara'a (31° 15'N, 35° 32'E). This may constitute the first solid evidence that the Biblical “cities of the Plain” (Sodom, Gommorah, etc.) were located there. Recent studies of earthquake deformations in the Lisan deposits near Bab-a-Dara'a, agree with our findings. At the present time, a magnitude 6¾ earthquake is pending at the northern edge of the Levant rift, with its average recurrence interval (83 years) exceeded by one standard deviation (32 years).

Tectonic significance of mesofracture systems associated with the Lebanese segment of the Dead Sea Transform fault

Article

Dec 1979
J STRUCT GEOL

A 3000 m Jurassic-Cretaceous-Palaeogene succession dominated by carbonates is deformed by NNE trending open folds of Palaeogene age. Conjugate wrench faults and a system of normal faults extend the fold belt axially and probably evolved during anticlockwise rotation in a transpressive regime related to the oblique convergence of the African and Arabian plates across the Lebanese segment of the Dead Sea transform fault. Three sets and four systems of conjugate mesoscopic fractures, symmetrically orientated with reference to bedding and the plunge of the fold in which they are contained, resulted in minor axial elongation. Pressure solution on surfaces striking parallel to the fold belt locally achieved up to 50% shortening.The N30°E vertical Yammouné Fault Zone, which connects with the principal rift faults to the north and south, is accompanied by mesostructures which indicate that displacements were dominantly left-lateral and that the 1–2 km Zone is younger than the folds, possibly of Neogene age.

Extended 14C database and revised CALIB radiocarbon calibration program

Article

Nov 1992
RADIOCARBON

Seismic reflection structure of intracratonic Palmyride fold-thrust belt and surrounding Arabian platform, Syria

Article

Mar 1990
AAPG BULL

Seismic reflection and drill-hole data from central Syria provide a detailed view of the subsurface structure (10-15 km depth) of the relatively little-studied intracratonic Palmyride fold and thrust belt. The data set, together with surface geologic mapping, constrains a structural/stratigraphic section spanning the northeast sector of the belt and the surrounding subprovinces of the Arabian platform. The seismic reflection and drill-hole data show Mesozoic stratigraphic sequences thickening abruptly into the Palmyrides from the adjacent, arched Paleozoic platforms Neogene (alpine) folding and thrusting of the Mesozoic basin, as documented on the seismic data, are sharply restricted to the narrow width of the belt ({approximately}100 km), in contrast to the relatively undeformed Phanerozoic strata of the platforms to the north and south. The seismic and drill-hole data support the hypothesis that the palmyrides began as a Permian-Triassic failed rift connected to the Levantine passive continental margin, which was inverted and complexly deformed by the interfering effects of Cenozoic movements along the Dead Sea transform fault system and the Turkish Bitlis convergent zone. The seismic data provide a first view into the extent and depth of the early basin formation and subsequent compressional deformation, and as such represent a necessary element for constraining reconstructions of northern Middle East plate motions. 20 figs.

IntCal98 radiocarbon age calibration

Article

Jan 1998
RADIOCARBON

The focus of this paper is the conversion of radiocarbon ages to calibrated (cal) ages for the interval 24,000–0 cal BP (Before Present, 0 cal BP = AD 1950), based upon a sample set of dendrochronologically dated tree rings, uranium-thorium dated corals, and varve-counted marine sediment. The 14 C age–cal age information, produced by many laboratories, is converted to Δ 14 C profiles and calibration curves, for the atmosphere as well as the oceans. We discuss offsets in measured l4 C ages and the errors therein, regional 14 C age differences, tree–coral 14 C age comparisons and the time dependence of marine reservoir ages, and evaluate decadal vs . single-year 14 C results. Changes in oceanic deepwater circulation, especially for the 16,000–11,000 cal BP interval, are reflected in the Δ 14 C values of INTCAL98.

INTCAL98 radiocarbon age calibration, 24,000-0 cal BP

Article

Jan 1998
RADIOCARBON

The focus of this paper is the conversion of radiocarbon ages to calibrated (cal) ages for the interval 24,000-0 cal BP (Before Present, 0 cal BP = AD 1950), based upon a sample set of dendrochronologically dated tree rings, uranium-thorium dated corals, and varve-counted marine sediment. The 14C age-cal age information, produced by many laboratories, is converted to Δ14C profiles and calibration curves, for the atmosphere as well as the oceans. We discuss offsets in measured 14C ages and the errors therein, regional 14C age differences, tree-coral 14C age comparisons and the time dependence of marine reservoir ages, and evaluate decadal vs. single-year 14C results. Changes in oceanic deepwater circulation, especially for the 16,000-11,000 cal BP interval, are reflected in the Δ14C values of INTCAL98.

Late Cenozoic uplift along the northern Dead Sea transform in Lebanon and Syria

Article

Jan 2006
EARTH PLANET SC LETT

Evidence of long-term, late Cenozoic uplift, as well as strike-slip faulting, is revealed by topographic and geological features along the northern 500 km of the Dead Sea fault system (DSFS)—the transform boundary between the Arabian and African plates in the eastern Mediterranean region. Macro-geomorphic features are studied using a new, high-resolution (20 m pixel) digital elevation model (DEM) produced by radar interferometry (InSAR). This DEM provides a spatially continuous view of topography at an unprecedented resolution along this continental transform from 32.5° to 38° N. This section of the left-lateral transform can be subdivided into a 200 km long Lebanese restraining bend (mostly in Lebanon), and the section to the north (northwest Syria). Spatial variations in Cenozoic bedrock uplift are inferred through mapping of topographic residuals from the DEM. Additionally, high altitude, low-relief surfaces are mapped and classified in the Mount Lebanon and Anti Lebanon ranges that also provide references for assessing net uplift. These results demonstrate an asymmetric distribution of post-Miocene uplift between the Mt. Lebanon and Anti Lebanon ranges. Antecedent drainages also imply that a major episode of uplift in the Palmyride fold belt post-dates the uplift of the Anti Lebanon region. North of the restraining bend, the Late Miocene surface is preserved beneath spatially extensive lava flows. Hilltop remnants of this paleosurface demonstrate Pliocene-Quaternary uplift and tilting of the Syrian Coastal Range, adjacent to the DSFS north of the restraining bend. This late Cenozoic uplift is contemporaneous with strike-slip along the DSFS. Geometrical relationships between folds and strike-slip features suggest that regional strain partitioning may accommodate a convergent component of motion between the Arabian and African plates. This interpretation is consistent with regional plate tectonic models that predict 10–25° of obliquity between the relative plate motion and the strike of the DSFS north of the restraining bend. We suggest that this convergent component of plate motion is responsible for uplift along and adjacent to the DSFS in the Syrian Coastal Range, as well as within the Lebanese restraining bend.

Evidence for 830 years of seismic quiescence from paleoseismology, archeoseismology and historical seismicity along the Dead Sea fault in Syria

Article

May 2003
EARTH PLANET SC LETT

The long historical record of earthquakes, the physical effects on ancient building structures and the palaeoseismology provide a unique opportunity for an interdisciplinary tectonic analysis along a major plate boundary and a realistic evaluation of the seismic hazard assessment in the Middle East. We demonstrate with micro-topographic surveys and trenching that the Dead Sea fault (DSF) offsets left-laterally by 13.6±0.2 m a repeatedly fractured ancient Roman aqueduct (older than AD 70 and younger than AD 30). Carbon-14 dating of faulted young alluvial deposits documents the occurrence of three large earthquakes in the past 2000 years between AD 100 and 750, between AD 700 and 1030 and between AD 990 and 1210. Our study provides the timing of late Holocene earthquakes and constrains the 6.9±0.1 mm/yr slip rate of the Dead Sea transform fault in northwestern Syria along the Missyaf segment. The antepenultimate and most recent faulting events may be correlated with the AD 115 and AD 1170 large earthquakes for which we estimate Mw=7.3–7.5. The ∼830 yr of seismic quiescence along the Missyaf fault segment implies that a large earthquake is overdue and may result in a major catastrophe to the population centres of Syria and Lebanon.

Constraining slip rates and spacings of active normal faults

Article

Dec 2001
J STRUCT GEOL

Numerous observations of extensional provinces indicate that neighbouring faults commonly slip at different rates and, moreover, may be active over different time intervals. These published observations include variations in slip rate measured along-strike of a fault array or fault zone, as well as significant across-strike differences in the timing and rates of movement on faults that have a similar orientation with respect to the regional stress field. Here we review published examples from the western USA, the North Sea, and central Greece, and present new data from the Italian Apennines that support the idea that such variations are systematic and thus to some extent predictable. The basis for the prediction is that: (1) the way in which a fault grows is fundamentally controlled by the ratio of maximum displacement to length, and (2) the regional strain rate must remain approximately constant through time. We show how data on fault lengths and displacements can be used to model the observed patterns of long-term slip rate where measured values are sparse. Specifically, we estimate the magnitude of spatial variation in slip rate along-strike and relate it to the across-strike spacing between active faults.

Constraints on the post ∼25-ka slip rate of the Yammoûneh fault (Lebanon) using in situ cosmogenic 36Cl dating of offset limestone-clast fans

Article

Oct 2004
EARTH PLANET SC LETT

The most active seismogenic structure along the eastern shore of the Mediterranean is the N–S-trending left-lateral Levant Fault System (LFS), the plate boundary between Arabia and Africa. In Lebanon, it forms a 160-km-long restraining bend responsible for the uplift of Mount Lebanon. The resulting transpression is partitioned between the offshore Tripoli–Roûm thrust and the Yammoûneh strike–slip fault. There are few quantitative constraints on the Quaternary slip rate along the LFS. Here we present a direct estimate of the ∼25-ka mean slip rate on the Yammoûneh fault. Mapped offsets of alluvial fans at two sites ∼50 km apart on the eastern flank of Mount Lebanon range between 24±2 and 80±8 m. About 30 limestone cobbles sampled on these fans yield in situ cosmogenic 36Cl exposure ages mostly between 6 and 27 ka. A statistical assessment of offsets versus ages provides bounds on the Late Pleistocene–Holocene slip rate on the fault: 3.8–6.4 mm/yr. These results are consistent with long-term geological inferences, confirming that the Yammoûneh fault is the main strike–slip branch of the LFS in Lebanon. They illustrate both the potential and the difficulties of using in situ cosmogenic 36Cl dating of limestone-clast fan deposits for deciphering tectonic and geomorphic processes in the Mediterranean.

The Dead Sea Transform fault system

Article

Aug 1990
TECTONOPHYSICS

R. W. Girdler

A new map showing the major features of the Dead Sea transform fault system based on seismicity, satellite imagery, geological maps and bathymetric charts is presented. Special attention is given to the possible northward continuation of the transform system beneath the Mediterranean Sea near Ed Damur, south of Beirut. The map shows the Dead Sea transform system to be a series of offset, overlapping, left-lateral transform faults with a rhombochasm between each pair. The system has similarities with the equatorial fracture zones in the Atlantic Ocean. Throughout, the Dead Sea transform system is considered in its regional setting, i.e. as extending from the Red Sea spreading centre in the south to the Eurasian collision zone in the north. It is suggested that it may intersect the latter somewhere east of Cyprus making that area the northernmost termination of the Dead Sea transform system.

Active tectonics along the Wadi-Araba-Jordan Valley transform fault

Article

Feb 1999
J GEOPHYS RES

Paolo Galli

A geological study has been carried out along the 200 km long Wadi Araba following the transform fault that separates the Arabian and Sinai-African Plates. Recent movements along this structure affect upper Pleistocene-Holocene deposits and archaeological sites. Kinematic indicators show sinistral strike-slip and oblique movements, in agreement with the relative motion between the two plates. Other evidence of recent horizontal displacement exists along the Jordan Valley Fault, both on the Dead Sea-Lake Tiberias segment and on the segment north of Lake Tiberias. A minimum horizontal slip rate of 1 cm/yr has been estimated for both the southern segment of the Wadi Araba Fault and for the southern Jordan River Fault. The two faults can be roughly subdivided into at least four segments: two in the Wadi Araba (80 km long each), one from the Dead Sea to Lake Tiberias (130 km), and one from Lake Tiberias to the Hula graben (>30 km). Faulting may also occur along shorter subsegments, as shown by bends in the

Plate kinematics of the circum Red Sea --- A re-evaluation

Article

Sep 1987
TECTONOPHYSICS

Instantaneous and finite kinematic models of plate motions in the Red Sea area were constructed based on a re-evaluation of the plate boundaries in the Afro-Arabian rift system. The kinematic analysis is a useful way to integrate data from all parts of the system in order to better define its overall history. The most important new aspect of the models is the treatment of the Dead Sea transform as a leaky, or transtensional, feature. The detailed structure of the transform allows accurate location of the Eulerian poles of its young (0-5 Ma) and total (0-25 Ma) motion at (32.8N, .22.6E) +-0.5 deg and (32.7N, 19.8E) +-2 deg, respectively. This constrains the Red Sea opening pole to (32.5N, 24.0E) +-2 deg; only such locations predict geometries of Suez rift opening compatible with its structure. The Gulf of Aden pole is relocated at (24.5N +- 0.5 deg, 26.0E +- 2 deg), about 5 deg southeast of previously accepted positions. The small differences between pole positions proposed here and previously accepted

GPS constraints on Africa (Nubia) and Arabia plate motions

Article

Oct 2003

We use continuously recording GPS (CGPS) and survey-mode GPS (SGPS) observations to determine Euler vectors for relative motion of the African (Nubian), Arabian and Eurasian plates. We present a well-constrained Eurasia-Nubia Euler vector derived from 23 IGS sites in Europe and four CGPS and three SGPS sites on the Nubian Plate (-0.95 +- 4.8N, -21.8 +- 4.3E, 0.06 +- 0.005 degMyr) . We see no significant (>1 mm yr-1) internal deformation of the Nubian Plate. The GPS Nubian-Eurasian Euler vector differs significantly from NUVEL-1A (21.0 +- 4.2N, -20.6 +- 0.6E, 0.12 +- 0.015 deg/Myr) , implying more westward motion of Africa relative to Eurasia and slower convergence in the eastern Mediterranean. The Arabia-Eurasia and Arabia-Nubia GPS Euler vectors are less well determined, based on only one CGPS and three SGPS sites on the Arabian Plate. The preliminary Arabia-Eurasia and Arabia-Nubia Euler vectors are 27.4 +- 1.0N, 18.4 +- 2.5E, 0.40 +- 0.04 deg/Myr, and 30.5 +- 1.0N, 25.7 +- 2.3E, 0.37 +- 0.04 deg/Myr

Holocene faulting and earthquake recurrence along the Serghaya branch of the Dead Sea fault system in Syria and Lebanon

Article

Jun 2003

The Serghaya fault, located approximately along the Syrian-Lebanese border, is a prominent structure within the 200 km restraining bend in the left-lateral Dead Sea fault system. This study documents palaeoseismic and geomorphic expressions of Holocene movements on the Serghaya fault based on trench excavations and radiocarbon dates. Trenches were excavated across and parallel to a 4.5 m fault scarp where Late Pleistocene sediments are faulted against Holocene alluvium and colluvium. Locally oblique slip on the Serghaya fault has produced a sequence of fault-derived colluvial wedges that distinguishes individual palaeoseismic events. In addition, the trench excavations also depict a sequence of buried and displaced channels. Our palaeoseismic study reveals evidence for five surface-rupturing events within the past ~6500 yr. The last event involved 2-2.5 m of primarily left-lateral displacement and may correspond to one of two historically documented earthquakes during the 18th century (in 1705 and 1759

Evidence of coseismic ruptures along the Roum fault (Lebanon): A possible source for the AD 1837 earthquake

Abstract

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