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Improvement to stochastic tsunami hazard analysis of megathrust earthquakes for western Makran subduction zone
Abstract
The Makran Subduction Zone (MSZ) is one of the world's most tsunami-prone regions. In the present study, tsunami hazards associated with potential MSZ earthquakes are evaluated using stochastic earthquake rupture modeling, which allows for the incorporation of uncertainties related to slip heterogeneity. Along the western segment of the MSZ, where tsunami hazard studies have received less attention, megathrust earthquakes with moment magnitudes of Mw 8.5, 8.7, and 8.9 are considered. The source parameters of 600 stochastic earthquake scenarios are calculated using the scaling relationships of Goda et al. (2016), which represent significant improvements over previous scaling relationships by taking into account the uncertainty of multiple source parameters and the coverage of a wide range of earthquake magnitudes. In order to simulate tsunami propagation and inundation, the nonlinear shallow water equations are used in four-level nested grid model domains .Ac-cording to the calculated slip fields, the seismic source characteristics provided by stochastic source models significantly change within the earthquake scenarios with identical magnitudes and may completely differ from the results of traditional uniform-slip source models. The results of the 600 Monte Carlo tsunami simulations demonstrate that even extremely large earthquakes in the west MSZ do not lead to significant tsunamis along the eastern coastal regions of Makran. The average maximum wave heights of 8, 10, and 17 m along the western Makran coasts, which correspond to the Mw 8.5, 8.7, and 8.9 scenarios, respectively, emphasize the severe potential threat of a possible tsunamigenic event in the west of the MSZ to the Iranian coasts. In addition, the significant difference between the maximum wave heights of the 10th and 90th percentiles for each scenario demonstrates the large variability of tsunami heights resulting from uncertainties associated with stochastic seismic source modeling. Thus, it can be concluded that the tsunami hazard parameters estimated by simple uniform-slip source models need to be revised in future tsunami risk assessment studies.
... Area megathrust subduksi yang terkunci berkorelasi dengan fitur bentang alam, memberikan bukti geomorfologi pengangkatan jangka panjang dan distribusi regangan, yang membantu membatasi bahaya seismik (Oryan et al., 2024). Analisis bahaya tsunami stokastik di daerah seperti Zona Subduksi Makran menunjukkan bahwa gempa bumi besar pun dapat menghasilkan dampak tsunami yang bervariasi akibat heterogenitas slip, sehingga menyoroti perlunya teknik pemodelan yang lebih canggih (Jannat et al., 2023). Di Indonesia, tsunami yang berasal dari sumber longsor dan vulkanik, seperti kejadian Anak Krakatau 2018, menunjukkan sifat tsunami yang tidak dapat diprediksi, sehingga perlu dilakukan penelitian lebih lanjut (Heidarzadeh et al., 2023). ...
Studi ini mengevaluasi upaya pemerintah Indonesia dalam memitigasi risiko gempa bumi megathrust, dengan fokus pada dua faktor penting: kesiapan infrastruktur dan edukasi publik. Pendekatan kuantitatif digunakan, dengan menggunakan survei yang didistribusikan kepada 200 responden di wilayah gempa berisiko tinggi. Hasilnya, yang dianalisis melalui Partial Least Squares Structural Equation Modeling (PLS-SEM), menunjukkan bahwa kesiapan infrastruktur dan pendidikan publik memiliki dampak positif yang signifikan terhadap efektivitas mitigasi risiko gempa bumi. Selain itu, studi ini juga menemukan bahwa pembangunan infrastruktur meningkatkan jangkauan dan efektivitas inisiatif pendidikan publik. Terlepas dari upaya-upaya tersebut, masih terdapat kesenjangan dalam partisipasi masyarakat dalam kegiatan kesiapsiagaan dan ketahanan infrastruktur dan utilitas transportasi terhadap gempa bumi. Studi ini memberikan wawasan yang dapat ditindaklanjuti oleh para pembuat kebijakan untuk memperkuat kesiapsiagaan bencana dengan mengintegrasikan pembangunan infrastruktur dengan kampanye pendidikan publik.
... Owing to the scarcity of historical tsunami source data in local areas, traditional statistical analysis methods cannot accurately assess tsunami disaster risks. Researchers have suggested employing the Monte Carlo method to generate stochastic sets of seismic random events for analyzing the risk of earthquake-induced tsunami disasters (Yuan et al., 2021;Mahmood et al., 2023). This method involves randomly generating calculation samples within potential earthquake source regions or applying random processes to certain seismic parameters. ...
Tsunamis, generated by submarine earthquakes, landslides, or volcanic eruptions, are a significant hazard to coastal areas owing to their sudden onset and rapid propagation speed. Thus, tsunami disaster risk assessment is crucial to determine potential losses and severity of future tsunami impacts, providing essential support for disaster prevention and mitigation efforts. This study presents a case study of Xiamen City in Fujian province for developing a high-precision tsunami model. Utilizing nearshore water depth and digital elevation model data, we established a high-resolution tsunami numerical simulation model for Xiamen City that accounts for the impact of water overrunning levees and overshoals. Historical tsunami disaster records were used to validate the numerical model. By determining multiple tsunami source scenarios that could potentially affect the counties of Xiamen City, we simulated the inundation range and water depth distribution required for the potential maximum tsunami event. The simulation results facilitated a tsunami hazard assessment. Considering land use and important tsunami-affected exposures including industrial and chemical enterprises and ports, we evaluated the vulnerability of Xiamen City to tsunami disasters. Based on the determination of hazard and vulnerability levels, we investigated the risk distribution of tsunami disasters in Xiamen City. The results of this study lay the groundwork for developing methodologies to improve tsunami disaster risk assessment in coastal areas.
In the wake of the unprecedented disaster caused by the 2004 and 2011 tsunamis, efforts by the scientific community have highlighted the important role of probabilistic tsunami hazard assessment (PTHA) in tsunami-prone areas. The Makran subduction zone (MSZ) is a hazardous tsunami-prone region; however, due to its low population density, it is not as prominent in the literature. In this study, we assess the threat a tsunami hazard poses to the coast of Iran and Pakistan by the MSZ and present a comprehensive PTHA for the entire coast regardless of population density. We accounted for sources of epistemic uncertainties by employing event tree and ensemble modeling. Aleatory variability was also considered through the probability density function. Further, we considered the contribution of small to large magnitudes and used our event trees to create a multitude of scenarios as initial conditions. Funwave-TVD was employed to propagate these scenarios. Our results demonstrate that the spread of hazard curves for different locations on the coast is remarkably large, and the probability that a maximum wave will exceed 3 m somewhere along the coast reaches for return periods , respectively. Moreover, we found that the exceedance probability could be higher at the west part of Makran for a long return period, if we consider it as active as the east part of the MSZ. Finally, we demonstrate that the contribution of aleatory variability is significant, and overlooking it leads to a significant hazard underestimation, particularly for a long return period.
Nankai–Tonankai megathrust earthquakes and tsunamis pose significant risks to coastal communities in western and central Japan. Historically, this seismic region hosted many major earthquakes, and the current national tsunami hazard assessments in Japan consider megathrust events as those having moment magnitudes between 9.0 and 9.1. In responding to the lack of rigorous uncertainty analysis, this study presents an extensive tsunami hazard assessment for the Nankai–Tonankai Trough events, focusing on the southwestern Pacific region of Japan. A set of 1000 kinematic earthquake rupture models is generated via stochastic source modelling approaches, and Monte Carlo tsunami simulations are carried out by considering high-resolution grid data of 10 m and coastal defence structures. Significant advantages of the stochastic tsunami simulation methods include the enhanced capabilities to quantify the uncertainty associated with tsunami hazard assessments and to effectively visualize the results in an integrated manner. The results from the stochastic tsunami simulations can inform regional and local tsunami risk reduction actions in light of inevitable uncertainty associated with such tsunami hazard assessments and complement conventional deterministic tsunami scenarios and their hazard predictions, such as those developed by the Central Disaster Management Council of the Japanese Cabinet Office.
Historical records of major earthquakes in the northwestern Indian Ocean along the Makran Subduction Zone (MSZ) indicate high potential tsunami hazards for coastal regions of Pakistan, Iran, Oman, and western India. There are fast-growing and populous cities and ports that are economically important, such as Chabahar (Iran), Gwadar (Pakistan), Muscat (Oman), and Mumbai (India). In this study, we assess the tsunami hazard of the 1945 MSZ event (fatalities ≈300 people) using stochastic earthquake rupture models of Mw 8.1–8.3 by considering uncertainties related to rupture geometry and slip heterogeneity. To quantify the uncertainty of earthquake source characteristics in tsunami hazard analysis, 1000 stochastic tsunami scenarios are generated via a stochastic source modeling approach. There are main objectives of this study: (1) developing stochastic earthquake slip models for the MSZ, (2) comparing results of the simulation with the existing observations of the 1945 event, and (3) evaluating the effect of uncertain fault geometry and earthquake slip based on simulated near-shore wave profiles. The 1945 Makran earthquake is focused upon by comparing model predictions with existing observations, consisting of far-field tsunami waveforms recorded on tide gauges in Karachi and Mumbai and coseismic deformation along the Pakistani coast. The results identify the source model that matches the existing observations of the 1945 Makran event best among the stochastic sources. The length, width, mean slip, and maximum slip of the identified source model are 270 km, 130 km, 2.9 m, and 19.3 m, respectively. Moreover, the sensitivity of the maximum tsunami heights along the coastline to the location of a large-slip area is highlighted. The maximum heights of the tsunami and coseismic deformation results at Ormara are in the range of 0.3–7.0 m and −2.7 to 1.1 m, respectively, for the 1000 stochastic source models.
The lack of offshore seismic data caused uncertainties associated with understating the behavior of future tsunamigenic earthquakes in the Makran subduction zone (MSZ). Future tsunamigenic events in the MSZ may trigger significant near-field tsunamis. Tsunami wave heights in the near field are controlled by the heterogeneity of slip over the rupture area. Considering a non-planar geometry for the Makran subduction zone, a range of random slip models were generated to hypothesize rupturing on the fault zone. We model tsunamis numerically and assess probabilistic tsunami hazard in the near field for all synthetic scenarios. The main affected areas by tsunami waves are the area between Jask and Ormara along the shorelines of Iran and Pakistan and the area between Muscat and Sur along the Oman coastline. The maximum peak-wave height along the shores of Iran and Pakistan is about 16 m and about for the Oman shoreline. The slip distributions control the wave height along the Makran coastlines. The dependency of tsunami height on the heterogeneity of slip is higher in the most impacted areas. Those areas are more vulnerable to tsunami hazard than other areas.
An updated global bathymetry and topography grid is presented using a spatial sampling interval of 15 arc seconds. The bathymetry is produced using a combination of shipboard soundings and depths predicted using satellite altimetry. New data consists of >33.6 million multi and singlebeam measurements collated by several institutions, namely, the National Geospatial‐Intelligence Agency, Japan Agency for Marine‐Earth Science and Technology, Geoscience Australia, Center for Coastal and Ocean Mapping and Scripps Institution of Oceanography. New altimetry data consists of 48, 14 and 12 months of retracked range measurements from Cryosat‐2, SARAL/AltiKa and Jason‐2 respectively. With respect to SRTM15_PLUS (Olson et al., 2016), the inclusion of these new data result in a ~1.4 km improvement in the minimum wavelength recovered for sea surface free‐air gravity anomalies, a small increase in the accuracy of altimetrically‐derived predicted depths and a 1.24 % increase, from 9.60 to 10.84 %, in the total area of ocean floor that is constrained by shipboard soundings at 15 arc second resolution. Bathymetric grid cells constrained by satellite altimetry have estimated uncertainties of ±150 m in the deep oceans and ±180 m between coastlines and the continental rise. Onshore, topography data are sourced from previously published digital elevation models, predominately SRTM‐CGIAR V4.1 between 60°N‐60°S. ArcticDEM is used above 60°N, while REMA is used below 62°S. Auxiliary grids illustrating shipboard data coverage, marine free‐air gravity anomalies and vertical gradient gradients are also provided in common data formats.
Abstract Tsunamis generated along the Makran subduction zone (MSZ) threaten the Sur coast of Oman, according to deterministic and probabilistic analyses presented here. A validated shallow water numerical code simulates the source-to-coast propagation and quantifies the coastal hazard in terms of maximum water level, flow depth, and inundation distance. The worst-case source assumed for the eastern MSZ is a thrust earthquake of Mw 8.8. This deterministic scenario produces simulated wave heights reaching 2.5 m on the Sur coast leading to limited coastal inundation extent. Because Oman adjoins the western MSZ, the probabilistic analysis includes the effect of this segment also. The probabilistic analysis shows onshore inundations exceeding 0.4 km northwest of Sur where flow depths are likely to exceed 1 m in 500 years. Probability analysis shows lesser inundation areas with probability of exceeding 1 m flow depth up to 80% in 500-year exposure time. Teletsunamis are excluded from these analyses because far-field waves of the 2004 Indian Ocean tsunami did not impact the Sur coast. Also excluded for simplicity are tsunamis generated by submarine slides within or near MSZ rupture areas. The results of this research provide essential information for coastal planning, engineering and management in terms of tsunami hazard and an essential step toward tsunami risk reductions in the northwest Indian Ocean.
The MAKRAN subduction zone, an approximate 1000 km section of the EURASIAN–ARABIAN plate, is located offshore of SOUTHERN IRAN and PAKISTAN. In 1945, the MAKRAN subduction zone (MSZ) generated a tsunamigenic earthquake with a magnitude of Mw 8.1. The region has also experienced large historical earthquakes but the data regarding these events are poorly documented. Therefore, the need to investigate tsunamis in MAKRAN must be taken into serious consideration. Using hydrodynamic numerical simulation, we evaluate the tsunami wave energy generated by bottom motion for a tsunamigenic source model distributed along the full length of the MAKRAN subduction zone. The whole rupture of the plate boundary is divided into 20 segments with width of the order of 200 km and a co-seismic slip of 10 m but with various lengths. Exchanges between kinetic and potential components of tsunami wave energy are shown. The total tsunami wave energy displays only 0.33 % of the seismic energy released from the earthquake source. As a result, for every increase in magnitude by one unit, the associated tsunami wave energy becomes about 10³ times greater.
We study the Makran subduction zone, along the southern coasts of Iran and Pakistan, to gain insights into the kinematics and dynamics of accretionary prism deformation. By combining techniques from seismology, geodesy and geomorphology, we are able to put constraints on the shape of the subduction interface and the style of strain across the prism. We also address the long-standing tectonic problem of how the right-lateral shear taken up by strike-slip faulting in the Sistan Suture Zone in eastern Iran is accommodated at the zone’s southern end. We find that the subduction interface in the western Makran may be locked, accumulating elastic strain, and move in megathrust earthquakes. Such earthquakes, and associated tsunamis, present a significant hazard to populations around the Arabian Sea. The time-dependent strain within the accretionary prism, resulting from the megathrust earthquake cycle, may play an important role in the deformation of the Makran region. By considering the kinematics of the 2013 Balochistan and Minab earthquakes, we infer that the local gravitational and far-field compressive forces in the Makran accretionary prism are in balance. This force balance allows us to calculate the mean shear stress and effective coefficient of friction on the Makran megathrust, which we find to be 5–35 MPa and 0.01–0.03, respectively. These values are similar to those found in other subduction zones, showing that the abnormally high sediment thickness in the offshore Makran does not significantly reduce the shear stress on the megathrust.
The tsunami of 27 November 1945 from an M w 8.1 earthquake in the Makran subduction zone is the only instrumentally recorded and deadly tsunami in the northwest of the Indian Ocean; offshore Iran, Pakistan, Oman, and India. Despite the fact that some source models have been proposed based on seismic or far-field tsunami data, none of them was able to reproduce one important observation: near-field runup of 10–12 m. Here, we applied numerical modeling and examined three possible secondary sources: (1) splay faulting, (2) delayed rupture of the earthquake source, and (3) submarine landslides. These secondary sources were added to the existing state-of-the-art earthquake source for this tsunami. Results of simulations revealed that only a submarine landslide with dimensions of 15 km (length) × 15 km (width), a thickness of 600 m, a volume of ∼40 km 3 , and located at 63.0° E and 24.8° N is capable of reproducing the near-field tsunami observation. Such a combined earthquake–landslide source is consistent with all available observations including far-field tsunami waveforms in Karachi (Pakistan) and Mumbai (India), with near-field runup height of 10–12 m, coastal co-seismic deformation data in Pasni (subsidence) and Ormara (uplift ∼1–3 m) and earthquake magnitude (M 8.0–8.3). Electronic Supplement: Tables listing parameters of splay fault and all landslide scenarios, and figures showing splay fault scenarios with deformation and coastal tsunami amplitudes.
This study assesses the tsunami hazard potential in Padang, Indonesia probabilistically using a novel stochastic tsunami simulation method. The stochastic tsunami simulation is conducted by generating multiple earthquake source models for a given earthquake scenario, which are used as input to run Monte Carlo tsunami simulation. Multiple earthquake source models for three magnitude scenarios, i.e., Mw 8.5, Mw 8.75, and Mw 9.0, are generated using new scaling relationships of earthquake source parameters developed from an extensive set of 226 finite-fault models. In the stochastic tsunami simulation, the effect of incorporating and neglecting the prediction errors of earthquake source parameters is investigated. In total, 600 source models are generated to assess the uncertainty of tsunami wave characteristics and maximum tsunami wave height profiles along coastal line of Padang. The results highlight the influence of the uncertainty of the scaling relationships on tsunami simulation results and provide a greater range of tsunamigenic scenarios produced from the stochastic tsunami simulation. Additionally, the results show that for the future major earthquakes in the Sunda megathrust, the maximum tsunami wave height in Padang areas can reach 20 m and, therefore, significant damage and loss may be anticipated in this region.
New scaling relationships of key earthquake source parameters are developed by uniformly and systematically analyzing 226 finite-fault rupture models from the SRCMOD database (http://equake-rc.info/srcmod/). The source parameters include the fault width, fault length, fault area, mean slip, maximum slip, Box-Cox power, correlation lengths along dip and strike directions, and Hurst number. The scaling relationships are developed by distinguishing tsunamigenic models from non-tsunamigenic models; typically, the former occurs in ocean and has gentler dip angles than the latter. The new models are based on extensive data, including recent mega-thrust events, and thus are more reliable. Moreover, they can be implemented as multivariate probabilistic models that take into account uncertainty and dependency of the multiple source parameters. The comparison between new and existing models indicates that the new relationships are similar to the existing ones for earthquakes with magnitudes up to about 8.0, whereas the relationships for the fault width and related parameters differ significantly for larger mega-thrust events. An application of the developed scaling relationships in tsunami hazard analysis is demonstrated by synthesizing stochastic earthquake source models in the Tohoku region of Japan. The examples are aimed at providing practical guidance as to how the developed scaling relationships can be implemented in stochastic tsunami simulation. The numerical results indicate that the effects of magnitude scaling of the source parameters and their uncertainties have major influence on the tsunami hazard assessment.
The Makran subduction zone (MSZ), located along the southern coasts of Iran and Pakistan, has experienced some deadly earthquakes and tsunamis, including the destructive 1945 Makran tsunami that led to more than 4000 fatalities. In spite of past studies on 1945 Makran tsunami, there are still unresolved problems, particularly on mismatches between the tsunami wave heights and arrival times with reported observations at different locations. The significant disagreement between the results of numerical models and existing data supports the existence of another mechanism involved during the generation of the tsunami. In the present study, a submarine landslide, triggered by the 1945 Earthquake, is studied as the major source of 1945 Makran tsunami. The simulation of seismic 1945 Tsunami, using high-resolution bathymetry data with a fine nested grid to increase the accuracy of modeled tsunami wave heights, confirms the large discrepancies between the reported tsunami waves and simulated values. Assuming the location and dimensions of a probable landslide, the GEOWAVE model, a combination of TOPICS and FUNWAVE models, is applied to model the non-seismic 1945 Tsunami. The simulated landslide tsunami demonstrates a fair agreement with the reported tsunami wave heights at different locations in Pakistan, Iran and India. The arrival times of tsunami waves at Pasni and Karachi in Pakistan can also be interpreted if the occurrence time of the probable submarine landslide is assumed with 3.5 h delay after the quake. The study highlights the potential danger of a non-seismic landslide tsunami in unconsolidated sediments at the MSZ and the necessity of the development of suitable countermeasures against other potential Makran tsunamis in future.
A large seismic gap lies along northern Chile and could potentially trigger a M
w ~ 8.8–9.0 megathrust earthquake as pointed out in several studies. The April 1, 2014, Pisagua earthquake broke the middle segment of the megathrust. Some slip models suggest that it ruptured mainly from a depth of 30 to 55 km along dip and over 180 km in length, reaching a magnitude M
w 8.1–8.2. The northern and southern segments are still unbroken; thus, there is still a large area that could generate a M
w > 8.5 earthquake with a strong tsunami. To better understand the effects of source parameters on the impact of a tsunami in the near field, as a case study, we characterize earthquake size for a hypothetical and great seismic event, M
w 9.0, in northern Chile. On the basis of physical earthquake source models, we generate stochastic k
−2 finite fault slips taking into account the non-planar geometry of the megathrust in northern Chile. We analyze a series of random slip models and compute vertical co-seismic static displacements by adding up the displacement field from all point sources distributed over a regular grid mesh on the fault. Under the assumption of passive generation, the tsunami numerical model computes the runup along the shore. The numerical results show a maximum peak-runup of ~35–40 m in the case of some heterogeneous slip models. Instead, the minimum runup along the coast, from the heterogeneous slip models tested, almost coincides with the runup computed from the uniform slip model. This latter assumption underestimates the runup by a factor of ~6 at some places along the coast, showing agreement with near-field runups calculated by other authors using similar methodologies, but applied in a different seismotectonic context. The statistical estimate of empirical cumulative distribution functions conducted on two subsets of slips, and their respective runups, shows that slip models with large amount of slip near the trench are more probable to produce higher runups than the other subset. The simple separation criterion was to choose slip models that concentrate at least 60 % of the total seismic moment in the upper middle part of the non-planar rupture fault.
This contribution to the Electronic Seismologist presents the online SRCMOD database of finite‐fault rupture models for past earthquakes, accessible at http://equake-rc.info/srcmod. Finite‐fault earthquake source inversions have become a standard tool in seismological research. Using seismic data, these inversions image the spatiotemporal rupture evolution on one or more assumed fault segments. If geodetic data are used, the source inversions put constraints on the fault geometry and the static slip distribution (i.e., final displacements over the fault surfaces). Joint inversions, using a combination of available seismic, geodetic, and potentially other data, try to match all observations to develop a more comprehensive image of the rupture process. Some joint inversions use all data simultaneously, whereas others take an iterative approach wherein one set of observations is utilized to construct an initial (prior) model for subsequent inversions using other available data.
The field of finite‐fault inversion was pioneered in the early 1980s (Olson and Apsel, 1982; Hartzell and Heaton, 1983). Subsequently, their method has been applied to numerous earthquakes (e.g., Hartzell, 1989; Hartzell et al. , 1991; Wald et al. , 1991; Hartzell and Langer, 1993; Wald et al. , 1993; Wald and Somerville, 1995), while simultaneously additional source‐inversion strategies were developed and applied (e.g., Beroza and Spudich, 1988; Beroza, 1991; Hartzell and Lui, 1995; Hartzell et al. , 1996; Zeng and Anderson, 1996). It is beyond the scope of this article to provide a detailed review of source‐inversion methods, their theoretical bases, implementations, and parameterizations; instead, we refer to Ide (2007) for a more comprehensive summary.
Finite‐fault source inversions help to shape our understanding of the complexity of the earthquake rupture process. These source images provide information, albeit at rather low spatial resolution, of earthquake slip at depth, and potentially also on the temporal rupture evolution. …
The 1945 Makran earthquake is known to have generated tsunami surges that affected the coasts of Iran, Pakistan, Oman and India. However, there is a significant delay in tsunami arrivals at various coastal sites with respect to the origin time of the earthquake. We explored the archival data to obtain arrival times and run-up heights at some important port cities along the Pakistan and Indian coasts. Numerical model for wave propagation based on the available rupture parameters predicts arrival times 17 and 28 min ahead of the actual arrival of the first surge at Karachi and Pasni respectively. There was also a significant discrepancy (>3 h) between the origin time of the earthquake and the observed arrival times of the second wave at various locations, which was the largest of the surges. We attribute this disparity in arrival time of the tsunami surges to submarine landslides triggered by the earthquake. Submarine slide-triggered tsunami is an underestimated threat in the Indian Ocean, and therefore, the regional tsunami hazard models of both the Arabian Sea and the Bay of Bengal should incorporate such overlooked mechanisms.
A probabilistic tsunami hazard assessment is performed for the Makran sub-duction zone (MSZ) at the northwestern Indian Ocean employing a combination of prob-ability evaluation of offshore earthquake occurrence and numerical modeling of resulting tsunamis. In our method, we extend the Kijko and Sellevoll's (1992) probabilistic analysis from earthquakes to tsunamis. The results suggest that the southern coasts of Iran and Pakistan, as well as Muscat, Oman are the most vulnerable areas among those studied. The probability of having tsunami waves exceeding 5 m over a 50-year period in these coasts is estimated as 17.5%. For moderate tsunamis, this probability is estimated as high as 45%. We recommend the application of this method as a fresh approach for doing probabilistic hazard assessment for tsunamis. Finally, we emphasize that given the lack of sufficient information on the mechanism of large earthquake generation in the MSZ, and inadequate data on Makran's paleo and historical earthquakes, this study can be regarded as the first generation of PTHA for this region and more studies should be done in the future. Keywords Probabilistic tsunami hazard assessment (PTHA) Á Seismic hazard analysis Á Numerical modeling Á Makran subduction zone (MSZ) Á Indian Ocean
We present a preliminary estimation of tsunami hazard associated with the Makran subduction zone (MSZ) at the northwestern Indian Ocean. Makran is one of the two main tsunamigenic zones in the Indian Ocean, which has produced some tsunamis in the past. Northwestern Indian Ocean remains one of the least studied regions in the world in terms of tsunami hazard assessment. Hence, a scenario-based method is employed to provide an estimation of tsunami hazard in this region for the first time. The numerical modeling of tsunami is verified using historical observations of the 1945 Makran tsunami. Then, a number of tsunamis each resulting from a 1945-type earthquake (M
w 8.1) and spaced evenly along the MSZ are simulated. The results indicate that by moving a 1945-type earthquake along the MSZ, the southern coasts of Iran and Pakistan will experience the largest waves with heights of between 5 and 7 m, depending on the location of the source. The tsunami will reach a height of about 5 m and 2 m in northern coast of Oman and eastern coast of the United Arab Emirates, respectively.
We evaluate here the tsunami hazard in the northwestern Indian Ocean. The maximum regional earthquake calculated from seismic hazard analysis, was used as the characteristic earthquake for our tsunami hazard assessment. This earthquake, with a moment magnitude of M
w
8.3 and a return period of about 1000 years, was moved along the Makran subduction zone (MSZ) and its possible tsunami wave height along various coasts was calculated via numerical simulation. Both seismic hazard analysis and numerical modeling of the tsunami were validated using historical observations of the Makran earthquake and tsunami of the 1945. Results showed that the possible tsunami may reach a maximum height of 9.6 m in the region. The distribution of tsunami wave height along various coasts is presented. We recommend the development of a tsunami warning system in the region, and emphasize the value of education as a measure to mitigate the death toll of a possible tsunami in this region.
The 27 November 1945 earthquake in the Makran Subduction Zone triggered a destructive tsunami that has left important problems unresolved. According to the available reports, high waves persisted along the Makran coast and at Karachi for several hours after the arrival of the first wave. Long-duration sea-level oscillations were also reported from Port Victoria, Seychelles. On the other hand, only one high wave was reported from Mumbai. Tide-gauge records of the tsunami from Karachi and Mumbai confirm these reports. While the data from Mumbai shows a single high wave, Karachi data shows that Electronic supplementary material The online version of this article (doi:10.1007/s11069-011-9854-0) contains supplementary material, which is available to authorized users. high waves persisted for more than 7 h, with maximum wave height occurring 2.8 h after the arrival of the first wave. In this paper, we analyze the cause of these persistent high waves using a numerical model. The simulation reproduces the observed features rea-sonably well, particularly the persistent high waves at Karachi and the single high wave at Mumbai. It further reveals that the persistent high waves along the Makran coast and at Karachi were the result of trapping of the tsunami-wave energy on the continental shelf off the Makran coast and that these coastally-trapped edge waves were trapped in the along-shore direction within a *300-km stretch of the continental shelf. Sensitivity experiments establish that this along-shore trapping of the tsunami energy is due to variations in the shelf width. In addition, the model simulation indicates that the reported long duration of sea-level oscillations at Port Victoria were mainly due to trapping of the tsunami energy over the large shallow region surrounding the Seychelles archipelago.
1] In contrast to far-field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes, there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment. From a global catalog of tsunami runup observations this variability is greatest for the most frequently occurring tsunamigenic subduction zone earthquakes in the magnitude range of 7 < M w < 8.5. Variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment: variations in the water depth in the source region, the combination of higher slip and lower shear modulus at shallow depth, and rupture complexity in the form of heterogeneous slip distribution patterns. The focus of this study is on the effect that rupture complexity has on the local tsunami wave field. A wide range of slip distribution patterns are generated using a stochastic, self-affine source model that is consistent with the falloff of far-field seismic displacement spectra at high frequencies. The synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field. For shallow subduction zone earthquakes it is demonstrated that self-affine irregularities of the slip distribution result in significant variations in local tsunami amplitude. The effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles. For a test region along the Pacific coast of central Mexico, peak nearshore tsunami amplitude is calculated for a large number (N = 100) of synthetic slip distribution patterns, all with identical seismic moment (M w = 8.1). Analysis of the results indicates that for earthquakes of a fixed location, geometry, and seismic moment, peak nearshore tsunami amplitude can vary by a factor of 3 or more. These results indicate that there is substantially more variation in the local tsunami wave field derived from the inherent complexity subduction zone earthquakes than predicted by a simple elastic dislocation model. Probabilistic methods that take into account variability in earthquake rupture processes are likely to yield more accurate assessments of tsunami hazards.
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
A complete suite of closed analytical expressions is presented for the surface displacements, strains, and tilts due to inclined shear and tensile faults in a half-space for both point and finite rectangular sources. These expressions are particularly compact and free from field singular points which are inherent in the previously stated expressions of certain cases. The expressions derived here represent powerful tools not only for the analysis of static field changes associated with earthquake occurrence but also for the modeling of deformation fields arising from fluid-driven crack sources.
The main objectives of this study are evaluating the statistical and spectral properties of tsunami waves as well as their energy behavior associated with the worst-case Makran seismic scenarios. The role of the Oman continental shelf in the tsunami wave propagation also investigated. In this study, the hybrid numerical model, GEOWAVE, is implemented for the entire life of the tsunami, including wave generation, propagation, and inundation. To study the statistical and frequency characteristics of the two worst-case tsunami waves (Mw 9.1 and 8.3), 36 artificial gage stations considered. The ports of Konarak, Sepah, Shahid Beheshti, Shahid Kalantari, and the Iran Bandar port were selected to analyze the frequency behavior of waves inside the ports. Based on spectral analysis of different stations in the Chabahar Bay, a two-period range of 15–25 min and 50–58 min for the Mw 9.1 are dominant. For the Mw 8.3, the maximum two dominant period ranges are 8–16 and 20–32 min. The wavelet analysis for Mw 9.1 indicates that for stations 1 to 30, the tsunami energy spread for the first 2 h after the tsunami arrived at these stations in a relatively wide range of 15–58 min, and then limited within the slightly narrower range. For Mw 8.3, the period range of 25–54 min for the first 4 h is dominant and then focuses on a smaller scope. Frequency-time graphs show that the energy of a tsunami can move between different period intervals at different times.
Despite the ambiguous tsunamigenic behavior of the Makran Subduction Zone (MSZ), due to the low level of offshore seismicity, historical evidences and the 1945 tsunami in Makran confirm the potential of the MSZ for generating tsunami events. Possible future tsunamis generated by the MSZ will pose the coastlines of Iran to hazard more than any other country. Probabilistic tsunami hazard assessment (PTHA) is an effective approach to assess hazard from tsunamis and help for planning for the future. In this study, we assess the probabilistic tsunami hazard along the southeastern coast of Iran considering the entire Makran, the western Makran and the eastern Makran tsunamigenic sources.
Tsunami scenarios include earthquakes of magnitudes between 7.5-8.9 for the western and eastern Makran and between 7.5-9.1 for the entire Makran. Both seismicity and tsunami numerical simulation are inputs for probabilistic hazard analysis. Assuming that the tsunami sources are capable of generating tsunamigenic earthquakes, estimating the annual rate of these events is required for PTHA. The truncated Gutenberg-Richter relation (Cosentino et al., 1977 and Weichert, 1980) is used in this study to compute the annual number of the earthquakes. We model tsunamis using the COMCOT well-known algorithm (Liu et al., 1998). The distributions of tsunami heights along the coastline of Iran are used in probabilistic tsunami hazard assessment.
The results of PTHA show that Konarak and Sirik coastlines are posed to the most and least hazard from tsunamis, respectively. The probability of exceeding (POE) 1 and 3 meters increases with time. The probability that tsunami wave height exceeds 3 meters in 500 years is about 0.63 and 0 near the coastlines of Konarak and Sirik, respectively. The maximum POE for 3 meters belongs to the area between Beris and the west of Kereti. Distributions of probabilistic tsunami height along the coastline of Iran also indicate that Konarak and Sirik are the most and least vulnerable shorelines to tsunami hazard, respectively. The annual probability of exceeding 1, 2 and 3 meters are 1, 0.4 and 0.2, respectively. The results indicate the need of attention to tsunami long-term hazard along the southeastern coast of Iran, especially for the area between Jask and Beris.
Our tsunami hazard assessment does not involve the tsunami inundation distances on dry land due to lack of high resolution site-specific bathymetric/topographic maps. Such computations are required in order to estimate the exact impacts of possible future tsunamis on the southeastern coast of Iran. High-resolution hydrographic surveys are required to be done in future for the major ports. Furthermore, future works should consider other possible near-field tsunami sources, such as the Murray Ridge, Minab-Zendan and Sonne faults and far-field tsunami sources, such as the Sumatra-Andaman subduction zone.
Tsunamis have repeatedly hit the shores of Oman (Northern Arabian Sea) in historical times (e.g. 1945, 2013). These events had small (< 3 m) wave heights and short inundation distances, but it is unclear if much stronger events can affect the area. Boulder deposits and fine-grained sediments are described from the north coast of Oman, which are interpreted as evidence for much larger pre-historic tsunami events. No systematic dating was available, which hampers interpretation. In this paper we report radiocarbon dating results for marine organisms in these deposits and present luminescence dating of fine-grained units. We document new sedimentological and
archaeological evidence for past tsunamis and describe new data on the impact of the 1945 Makran tsunami in Oman. Since the coast of Oman is prone to tropical storms, we discuss the possibility of sediment transport by
cyclones and we compare our findings with recent evidence of boulder transport by storms worldwide. We argue
that our results favor an interpretation as tsunamites based on sedimentological, archaeological, and spatial
criteria. The dating results allow us to show that a tsunami hit the northern coast of Oman around 1000 years
ago. A comparison with historical tsunami impact indicates that this palaeo-event exceeded in size all modern
examples in the study area. We speculate that only a large earthquake at the Makran Subduction Zone can
produce a tsunami of this size. In that case, the earthquake might have at least partially ruptured the western
Makran, which would imply that the western Makran is not completely unlocked. Hazard scenarios based on
historical data underestimate the tsunami threat in the Northern Arabian Sea.
The Sultanate of Oman is among the Indian Ocean
countries that were subjected to at least two confirmed tsunamis
during the twentieth and twenty-first centuries: the 1945 tsunami
due to an earthquake in the Makran subduction zone in the
Sea of Oman (near-regional field tsunami) and the Indian Ocean
tsunami in 2004, caused by an earthquake from the Andaman
Sumatra subduction zone (far - field tsunami). In this paper, we
present a probabilistic tsunami hazard assessment for the entire
coast of Oman from tectonic sources generated along the
Makran subduction zone. The tsunami hazard is assessed taking
into account the contribution of small- and large-event magnitudes.
Results of the earthquake recurrence rate studies and the
tsunami numerical modeling for different magnitudes were
used through a logic-tree to estimate the tsunami hazard probabilities.
We derive probability hazard exceedance maps for the
Omani coast considering the exposure times of 100, 250, 500,
and 1000 years. The hazard maps consist of computing the
likelihood that tsunami waves exceed a specific amplitude.
We find that the probability that a maximum wave amplitude
exceeds 1 m somewhere along the coast of Oman reaches,
respectively, 0.7 and 0.85 for 100 and 250 exposure times,
and it is up to 1 for 500 and 1000 years of exposure times.
These probability values decrease significantly toward the
southern coast of Oman where the tsunami impact, from the
earthquakes generated at Makran subduction zone, is low.
The Sultanate of Oman is among the Indian Ocean countries that were subjected to at least two confirmed tsunamis during the twentieth and twenty-first centuries: the 1945 tsunami due to an earthquake in the Makran subduction zone in the Sea of Oman (near-regional field tsunami) and the Indian Ocean tsunami in 2004, caused by an earthquake from the Andaman Sumatra subduction zone (far - field tsunami). In this paper, we present a probabilistic tsunami hazard assessment for the entire coast of Oman from tectonic sources generated along the Makran subduction zone. The tsunami hazard is assessed taking into account the contribution of small- and large-event magnitudes. Results of the earthquake recurrence rate studies and the tsunami numerical modeling for different magnitudes were used through a logic-tree to estimate the tsunami hazard probabilities. We derive probability hazard exceedance maps for the Omani coast considering the exposure times of 100, 250, 500, and 1000 years. The hazard maps consist of computing the likelihood that tsunami waves exceed a specific amplitude. We find that the probability that a maximum wave amplitude exceeds 1 m somewhere along the coast of Oman reaches, respectively, 0.7 and 0.85 for 100 and 250 exposure times, and it is up to 1 for 500 and 1000 years of exposure times. These probability values decrease significantly toward the southern coast of Oman where the tsunami impact, from the earthquakes generated at Makran subduction zone, is low.
The Makran subduction zone is one of the last convergent margins to be investigated using space-based geodesy. While there is a lack of historical and modern instrumentation in the egion, a sparse sampling of continuous and campaign measurements over the past decade has allowed us to make the first estimates of convergence rates. We combine GPS measurements from 20 stations located in Iran, Pakistan and Oman along with hypocentral locations from the International Seismological Centre to create a preliminary 3-D estimate of the geometry of themegathrust, along with a preliminary fault-coupling model for the Makran subduction zone. Using a convergence rate which is strongly constrained by measurements from the incoming Arabia plate along with the backslip method of Savage, we find the Makran subduction zone appears to be locked to a depth of at least 38 km and accumulating strain. We also find evidence for a segmentation of plate coupling, with a 300 km long section of reduced plate coupling. The range of acceptable locking depths from our modelling and the 900 km along-strike length for the megathrust, makes the Makran subduction zone capable of earthquakes up to Mw = 8.8. In addition, we find evidence for slow-slip-like transient deformation events on two GPS stations. These observations are suggestive of transient deformation events observed in Cascadia, Japan and elsewhere.
A complete set of closed analytical expressions is presented in a unified manner for the internal displacements and strains due to shear and tensile faults in a half-space for both point and finite rectangular sources. Several practical suggestions to avoid mathematical singularities and computational instabilities are presented. -from Author
The aseismic Murray ridge (MR) is a continuation of the Owen fracture zone which marks
the boundary between the Indian and Arabian plates. Due to large variation in morphology
and structure within this NE–SW trending ridge in the Arabian Sea a large variation of the
bathymetry from few hundred metres to about 4000 m is seen. Observed seismicity on the
ridge system is predominantly strike-slip. Tsunamis generated in the Makran subduction zone
(MSZ) will propagate through the MR system due to its proximity. As the tsunami speed
depends on the depth of the ocean, bathymetry plays a vital role on tsunami propagation.
In this paper, the effect of tsunami propagation through the MR system is carried out with
the existing bathymetry and comparing the results by removing the bathymetry. To study this
phenomenon the 1945 Makran tsunami and worst possible tsunamigenic earthquakes form
eastern and western MSZ are considered. The directivity of tsunami propagation with the
ridge system is seen to change after crossing the MR towards the southeast direction for
tsunamis generated in the eastern MSZ. For tsunami generated in the western MSZ there is
no change in its directivity and is almost same as without the ridge with propagation being
towards the open sea. Hence the MR not only affects the amplitude of the tsunamis but also
the directionality and the arrival times.
[1] Scaling relations for seismic moment M0, rupture area S, average slip D, and asperity size Sa were obtained for large, great, and giant (Mw = 6.7–9.2) subduction-zone earthquakes. We compiled the source parameters for seven giant (Mw~9) earthquakes globally for which the heterogeneous slip distributions were estimated from tsunami and geodetic data. We defined Sa for subfaults exhibiting slip greater than 1.5 times D. Adding 25 slip models of 10 great earthquakes around Japan, we recalculated regression relations for 32 slip models: S = 1.34 × 10−10 M02/3, D = 1.66 × 10−7 M01/3, Sa = 2.81 × 10−11 M02/3, and Sa/S = 0.2, where S and Sa are in square kilometers, M0 is in newton meters, and D is in meters. These scaling relations are very similar to those obtained by Murotani et al. (2008) for large and great earthquakes. Thus, both scaling relations can be used for future tsunami hazard assessment associated with a giant earthquake.
The Makran subduction zone experienced a tsunamigenic Mw 8.1
earthquake in 1945 and recent, smaller earthquakes also suggest
seismicity on the megathrust; however, its historical record is limited
and hazard potential enigmatic. We have developed a 2-D thermal model of
the subduction zone. The results are twofold: (1) The thick sediment
cover on the incoming plate leads to high (~150°) plate boundary
temperatures at the deformation front making the megathrust potentially
seismogenic to a shallow depth, and (2) the shallow dip of the
subducting plate leads to a wide potential seismogenic zone (up to ~350
km). Combining these results with along strike rupture scenarios
indicates that Mw8.7-9.2 earthquakes are possible in the
seaward Makran subduction zone. These results have important earthquake
and tsunami hazard implications, particularly for the adjacent
coastlines of Pakistan, Iran, Oman, and India, as the Makran has not
been previously considered a likely candidate for a Mw > 9
earthquake.
Finite-fault source inversions reveal the spatial complexity of earthquake slip over the fault plane. We develop a stochastic characterization of earthquake slip complexity, based on published finite-source rupture models, in which we model the distribution of slip as a spatial random field. The model most consistent with the data follows a von Karman autocorrelation function (ACF) for which the correlation lengths a increase with source dimension. For earthquakes with large fault aspect ratios, we observe substantial differences of the correlation length in the along-strike (ax) and downdip (az) directions. Increasing correlation length with increasing magnitude can be understood using concepts of dynamic rupture propagation. The power spectrum of the slip distribution can also be well described with a power law decay (i.e., a fractal distribution) in which the fractal dimension D remains scale invariant, with a median value D = 2.29 ± 0.23, while the corner wave number kc, which is inversely proportional to source size, decreases with earthquake magnitude, accounting for larger “slip patches” for large-magnitude events. Our stochastic slip model can be used to generate realizations of scenario earthquakes for near-source ground motion simulations.
We evaluate far-field tsunami hazard in the Indian Ocean Basin based on hydrodynamic simulations of ten case studies of possible mega earthquakes at the major seismic zones surrounding the basin. They represent worst-case scenarios of seismic rupture along the full extent of seismogenic faults having supported large earthquakes in the historical record. In a series of numerical experiments in which the source parameters of the 2004 Sumatra tsunami are allowed to vary one by one, while keeping the seismic moment and the fault orientation unchanged, we document that the main patterns of far-field tsunami amplitudes are remarkably robust with respect to nominal variations in such parameters as hypocentral depth, exact centroid location, and slip distribution on the fault plane. These results validate the concept of modelling case scenarios of potential future earthquakes whose source is by definition imprecise.
We consider seismic sources located at the extremities of the 2004 Sumatra–Andaman rupture, namely along the southern coast of Sumatra and in the Andaman–Myanmar province; along the Makran coast of Pakistan and Iran; and also along the southern coast of Java, where the possibility of a large interplate thrust earthquake cannot be entirely dismissed. The results of our hydrodynamic simulations indicate that the distribution of maximum amplitudes in the Indian Ocean Basin is primarily controlled by the classical effect of source directivity, and additionally by refraction and focusing along bathymetric features. As a result, many provinces in the basin could be threatened by higher tsunami amplitudes than in 2004. This pattern is particularly important along the coast of East Africa, from Somalia to and including South Africa, in Madagascar and the Mascarene Islands, especially under a South Sumatra scenario involving an earthquake comparable to, or even possibly larger than, the 1833 event, whose epicentral area is widely believed to be under enhanced seismic risk as a result of stress transfer from the 2004 and 2005 ruptures to the northwest, possibly even in the wake of the 2007 Bengkulu earthquakes.
Earthquake rupture length and width estimates are in demand in many seismological applications. Earthquake magnitude estimates are often available, whereas the geometrical extensions of the rupture fault mostly are lacking. Therefore, scaling relations are needed to derive length and width from magnitude. Most frequently used are the relationships of Wells and Coppersmith (1994) derived on the basis of a large dataset including all slip types with the exception of thrust faulting events in subduction environments. However, there are many applications dealing with earthquakes in subduction zones because of their high seismic and tsunamigenic potential. There are no well-established scaling relations for moment magnitude and length/width for subduction events. Within this study, we compiled a large database of source parameter estimates of 283 earthquakes. All focal mechanisms are represented, but special focus is set on (large) subduction zone events, in particular. Scaling relations were fitted with linear least-square as well as orthogonal regression and analyzed regarding the difference between continental and subduction zone/oceanic relationships. Additionally, the effect of technical progress in earthquake parameter estimation on scaling relations was tested as well as the influence of different fault mechanisms. For a given moment magnitude we found shorter but wider rupture areas of thrust events compared to Wells and Coppersmith (1994). The thrust event relationships for pure continental and pure subduction zone rupture areas were found to be almost identical. The scaling relations differ significantly for slip types. The exclusion of events prior to 1964 when the worldwide standard seismic network was established resulted in a remarkable effect on strike-slip scaling relations: the data do not show any saturation of rupture width of strike- slip earthquakes. Generally, rupture area seems to scale with mean slip independent of magnitude. The aspect ratio L/W, however, depends on moment and differs for each slip type.
Finite-source images of earthquake rupture show that fault slip is spa-tially variable at all resolvable scales. In this study we develop scaling laws that account for this variability by measuring effective fault dimensions derived from the autocorrelation of the slip function for 31 published slip models of 18 earthquakes, 8 strike-slip events, and 10 dip-slip (reverse, normal, or oblique) events. We find that dip-slip events show self-similar scaling, but that scale invariance appears to break down for large strike-slip events for which slip increases with increasing fault length despite the saturation of rupture width. Combining our data with measure-ments from other studies, we find evidence for a nonlinear relationship between average displacement and fault length, in which displacement increases with fault length at a decreasing rate for large strike-slip events. This observation is inconsistent with pure width or length scaling for simple constant stress-drop models, but suggests that the finite seismogenic width of the fault zone exerts a strong influence on the displacement for very large strike-slip earthquakes.
The Fourier Integral Method (FIM) of spectral simulation, adapted to generate realizations of a random function in one, two, or three dimensions, is shown to be an efficient technique of non-conditional geostatistical simulation. The main contribution is the use of the fast Fourier transform for both numerical calculus of the density spectral function and as generator of random finite multidimensional sequences with imposed covariance. Results obtained with the FIM are compared with those obtained by other classic methods: Shinozuka and Jan Method in 1D and Turning Bands Method in 2D and 3D, the points for and against different methodologies are discussed. Moreover, with the FIM the simulation of nested structures, one of which can be a nugget effect and the simulation of both zonal and geometric anisotropy is straightforward. All steps taken to implement the FIM methodology are discussed.
Numerical method of tsunami simulation with the leap-frog scheme
- Goto
Goto, C., Ogawa, Y., Shuto, N., Imamura, F., 1997. Numerical method of tsunami
simulation with the leap-frog scheme. IOC Manuals and Guides 35, 130.
Early to middle Jurassic radiolarian fauna from the Ras Koh arc and its tectonostratigraphic significance
- R H Siddiqui
- T Naka
- I A Brohi
Siddiqui, R.H., Naka, T., Brohi, I.A., 2009. Early to middle Jurassic radiolarian fauna
from the Ras Koh arc and its tectonostratigraphic significance. Sind Univ. Res. J. Sci.
Ser. 41 (1), 107-118.
Early to middle Jurassic radiolarian fauna from the Ras Koh arc and its tectonostratigraphic significance
- Siddiqui
Evaluating Tsunami Hazard in the
- Heidarzadeh