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Calibrating a new attenuation curve for the Dead Sea region using surface wave dispersion surveys in sites damaged by the 1927 Jericho earthquake


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Instrumental strong motion data are not common around the Dead Sea region. Therefore, calibrating a new attenuation equation is a considerable challenge. However, the Holy Land has a remarkable historical archive, attesting to numerous regional and local earthquakes. Combining the historical record with new seismic measurements will improve the regional equation. On 11 July 1927, a rupture, in the crust in proximity to the northern Dead Sea, generated a moderate 6.2 ML earthquake. Up to 500 people were killed, and extensive destruction was recorded, even as far as 150 km from the focus. We consider local near-surface properties, in particular, the shear-wave velocity, as an amplification factor. Where the shear-wave velocity is low, the seismic intensity far from the focus would likely be greater than expected from a standard attenuation curve. In this work, we used the multichannel analysis of surface waves (MASW) method to estimate seismic wave velocity at anomalous sites in Israel in order to calibrate a new attenuation equation for the Dead Sea region. Our new attenuation equation contains a term which quantifies only lithological effects, while factors such as building quality, foundation depth, topography, earthquake directivity, type of fault, etc. remain out of our scope. Nonetheless, about 60 % of the measured anomalous sites fit expectations; therefore, this new ground-motion prediction equation (GMPE) is statistically better than the old ones. From our local point of view, this is the first time that integration of the 1927 historical data and modern shear-wave velocity profile measurements improved the attenuation equation (sometimes referred to as the attenuation relation) for the Dead Sea region. In the wider context, regions of low-to-moderate seismicity should use macroseismic earthquake data, together with modern measurements, in order to better estimate the peak ground acceleration or the seismic intensities to be caused by future earthquakes. This integration will conceivably lead to a better mitigation of damage from future earthquakes and should improve maps of seismic hazard.
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Solid Earth, 10, 379–390, 2019
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Calibrating a new attenuation curve for the Dead Sea region using
surface wave dispersion surveys in sites damaged by
the 1927 Jericho earthquake
Yaniv Darvasi and Amotz Agnon
The Fredy & Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, 9190401 Jerusalem, Israel
Correspondence: Yaniv Darvasi (
Received: 3 June 2018 – Discussion started: 7 June 2018
Revised: 10 February 2019 – Accepted: 12 February 2019 – Published: 7 March 2019
Abstract. Instrumental strong motion data are not common
around the Dead Sea region. Therefore, calibrating a new at-
tenuation equation is a considerable challenge. However, the
Holy Land has a remarkable historical archive, attesting to
numerous regional and local earthquakes. Combining the his-
torical record with new seismic measurements will improve
the regional equation.
On 11 July 1927, a rupture, in the crust in proximity to the
northern Dead Sea, generated a moderate 6.2 MLearthquake.
Up to 500 people were killed, and extensive destruction was
recorded, even as far as 150 km from the focus. We con-
sider local near-surface properties, in particular, the shear-
wave velocity, as an amplification factor. Where the shear-
wave velocity is low, the seismic intensity far from the focus
would likely be greater than expected from a standard atten-
uation curve. In this work, we used the multichannel analysis
of surface waves (MASW) method to estimate seismic wave
velocity at anomalous sites in Israel in order to calibrate a
new attenuation equation for the Dead Sea region.
Our new attenuation equation contains a term which quan-
tifies only lithological effects, while factors such as building
quality, foundation depth, topography, earthquake directivity,
type of fault, etc. remain out of our scope. Nonetheless, about
60 % of the measured anomalous sites fit expectations; there-
fore, this new ground-motion prediction equation (GMPE) is
statistically better than the old ones.
From our local point of view, this is the first time that
integration of the 1927 historical data and modern shear-
wave velocity profile measurements improved the attenua-
tion equation (sometimes referred to as the attenuation rela-
tion) for the Dead Sea region. In the wider context, regions of
low-to-moderate seismicity should use macroseismic earth-
quake data, together with modern measurements, in order to
better estimate the peak ground acceleration or the seismic
intensities to be caused by future earthquakes. This integra-
tion will conceivably lead to a better mitigation of damage
from future earthquakes and should improve maps of seis-
mic hazard.
1 Introduction
Generating a modern and applicable attenuation equation is
one of applied seismologists’ main interests. Considering the
Dead Sea area, for which instrumental strong motion data are
not available, this task is particularly challenging. Using the
Holy Land’s historically rich database, researchers had de-
fined seismic intensities and estimated earthquake locations.
Investigating anomalous sites, with seismic intensities higher
or lower than predicted from the basic regional attenuation
relation, may lead to a better attenuation equation. The local
geological conditions can strongly influence the nature and
severity of shaking at a given site. Assessing the local geo-
logical conditions by geophysical techniques at these anoma-
lous sites, and adding a logarithmic term to a basic attenua-
tion equation, should improve the equation.
This work focuses on the 1927 event, but it is part of wider
research which extends to additional earthquakes. The 1927
event was chosen as it is the only devastating one recorded,
albeit teleseismically, during the instrumented period.
Our main goal in this research is a tighter constraint on
the attenuation equation derived from this event. This should
allow us to examine whether this preliminary work coin-
Published by Copernicus Publications on behalf of the European Geosciences Union.
380 Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve
Figure 1. Schematic view of site amplification. Seismogram at the
surface shows amplification in comparison to the seismogram lo-
cated over the bedrock (modified after Ciaccio and Cultrera, 2014).
cides with our expectations of site amplification and de-
amplification due to the local lithology.
1.1 Site response
Ground motion is controlled by a number of variables, in-
cluding source characteristics, source distance, propagation
directivity, near-surface geology, etc. The elastic properties
of near-surface materials and their effect on seismic wave
propagation are crucial to earthquake and civil engineering,
and environmental and Earth science studies.
Seismic surface waves are initiated at the moment that
the earthquake wave front impinges on the surface. These
waves spread out, and the surface shakes as they pass. Sur-
face wave amplitude at the surface is controlled by the me-
chanical properties of the rocks below. These often consist of
low-velocity weathered rock over bedrock with much higher
velocities. When seismic waves pass from a high-velocity
layer to a low-velocity layer, their amplitudes and duration
typically increase. The phenomena of site amplification, as
a result of soft sediments overlying hard bedrock, is well
known since the early days of seismology (Milne, 1898).
Site effects are also well known and were investigated af-
ter several major earthquakes: Mexico City 1985 (Singh et
al., 1988), Yerevan 1989 (Borcherdt et al., 1989), San Fran-
cisco 1989 (Hough et al., 1990), Los Angeles 1994 (Hall et
al., 1994) and Kobe 1995 (Aguirre and Irikura, 1997). There-
fore, local lithology is a crucial factor for estimating site am-
plification, defined as the amplitude ratio between the sur-
face layer and the underlying bedrock. Site amplification at a
specific site can be attributed to many factors, such as basin
effects, focusing effects, topography and reverberation of the
seismic waves in the upper layers due to acoustic impedance
differences (Fig. 1).
The amplification, A, is proportional to the reciprocal
square root of the product of the shear-wave velocity, Vs
(Eq. 1) (Aki and Richards, 2002):
where ρis the density of the investigated soil. As shear-wave
velocity decreases by a given fraction, the amplification in-
creases by half that fraction (for a constant density). Since
density plays a minor role (Dal Moro, 2014; Xia et al., 1999),
the Vsvalue can be used to represent site conditions.
The most widely used index in the classification of the soil
response is the average shear-wave velocity in the uppermost
30 m, the Vs30 . This index was accepted for site classification
in the US National Earthquake Hazards Reduction Program
(NEHRP) (Building Seismic Safety Council, 2001). In Eu-
rope, by the new provisions of Eurocode 8 (CEN, 2011), and
in Israel, it is accepted by the design provisions for earth-
quake resistance of structures – SI 413 (The Standards In-
stitution of Israel, 2013). The value of 30 m comes from the
US and European building codes, where it was found empir-
ically that this depth is directly proportional to deeper and
shallower values (Boore et al., 2011). Zaslavsky et al. (2012)
argued that the use of Vs30 is a simplification that cannot be
justified in the complex geological conditions in Israel, yet
no alternatives have thus far been proposed. Therefore, in
this scenario, the Standards Institution of Israel still adopts
the Vs30 index.
In modern attenuation equations, also known as ground-
motion prediction equations (GMPEs), coefficients are de-
rived from strong motion data, namely from ground accel-
eration measurements. In the past, and in areas lacking the
technology to record earthquakes, it was impossible to mea-
sure the peak ground acceleration (PGA) directly. Therefore,
it is common to categorize historical earthquakes with seis-
mic intensity scales that describe the damage at each site or
area (Ambraseys, 2009; Guidoboni and Comastri, 2005).
1.2 The 6.2 ML1927 Jericho earthquake
The left-lateral Dead Sea transform separates the Sinai–
Levant Block from the Arabian Plate (Fig. 2). The 6.2 ML
11 July 1927 Jericho earthquake (Ben-Menahem et al., 1976;
Shapira, 1979) was the strongest and most destructive earth-
quake to hit the Holy Land during that century. Furthermore,
it was the first to be instrumentally recorded by seismo-
graphs. The epicentral location was originally estimated to be
a few kilometers south of the Damia Bridge, which is 30 km
north of Jericho (International Seismological Summary – ISS
Bulletin of 1927). In the following decades, new estimates
have been published: Shapira et al. (1993) calculated the epi-
center to be near Mitzpe Shalem. Zohar and Marco (2012) es-
timated the epicenter to be near the Almog settlement, about
30 km north of Shapira’s epicenter, and Kagan et al. (2011)
surmised that the source was somewhere on the Kalia fault,
located in the northern part of the Dead Sea graben, perpen-
dicular to the main Dead Sea fault (Fig. 2).
The damage from the earthquake was heavy, especially in
places near the source but not only there. In Nablus, located
70 km from the epicenter (Fig. 2), 60 people were killed,
474 were injured, and more than 700 structures were de-
Solid Earth, 10, 379–390, 2019
Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve 381
Figure 2. Research area: (a) Middle East area with the main tec-
tonic elements. (b) Proposed epicenters for the 1927 earthquake
event with all sites that were investigated placed over a 25 m dig-
ital terrain model (DTM) image (Hall, 2008). (c) Detailed location
of the proposed epicenters. Also shown are sites mentioned in the
text: Jerusalem (J) and Nablus (N).
stroyed, most of which were built on soft sediments (Blanck-
enhorn, 1927; Willis, 1928). By comparison, Jerusalem is
only about 30 km from the source and the damage there
was much smaller, especially in property. However, at Mount
Scopus and the Mount of Olives (eastern neighborhoods
in Jerusalem), the damage exceeded that in other parts of
Jerusalem (Abel, 1927; Brawer, 1928). Other cities also suf-
fered from this earthquake. Tens of people were injured and
even died, and hundreds of houses were ruined in Ramla
and Lod (Brawer, 1928). Jericho in the Jordan Valley also
suffered significant damage, especially in terms of build-
ings collapsing (Fig. 3). The total number of victims was
about 350–500 (Ambraseys and Melville, 1988; Amiran,
1952; Arieh, 1967; Ben-Menahem, 1991). Beyond the casu-
alties, several environmental effects were reported. The Jor-
dan River flow ceased near the Damia Bridge for about 21.5h
(Willis, 1928) and a 1 m seiche wave was observed in the
Dead Sea (Abel, 1927; Blanckenhorn, 1927). Some evidence
suggests that the earthquake was felt up to 700 km from the
Figure 3. Wreckage of the Winter Palace Hotel, Jericho, after the
1927 earthquake. American Colony (Jerusalem). Photo Dept., pho-
epicenter (Ben-Menahem, 1991), although a different inter-
pretation suggests this distance was only 300 km (Ambraseys
and Melville, 1988).
Compiling historical evidence, Avni (1999), in his
PhD thesis, estimated the seismic intensities (MSK or
the Medvedev–Sponheuer–Karnik scale) (Medvedev et al.,
1965) at 133 different locations around Israel, Palestine, Jor-
dan, Lebanon, Syria and Egypt (Fig. 4 for locations and
the Supplement). The curve that Avni (1999) fit to his scat-
tered MSK vs. dpoints represents his basic attenuation equa-
tion and had an R2of about 0.26. Based on the methodol-
ogy proposed by Bakun and Wentworth (1997), Hough and
Avni (2011) published a new attenuation equation for the
Dead Sea region:
MMI(M, d )= −0.64+1.7M0.00448d1.67log(d), (2)
where MMI is the modified Mercalli intensity (assumed to
be equivalent to MSK), Mis the magnitude, and dis the
distance from the epicenter.
2 Methods – multichannel analysis of surface waves
The multichannel analysis of surface waves (MASW)
method is environmentally friendly, non-invasive, low cost,
rapid and robust, and provides reliable Vs30 data (Xia et al.,
2002). Multichannel shallow seismic surveys make it pos-
sible to separate different wave fields in the frequency and
velocity domains. Fundamental and higher modes can be an-
alyzed simultaneously, but generally, only the fundamental
mode is used because it has the highest energy (Park et al.,
The MASW method consists of three main steps: (a) ac-
quisition of experimental data, (b) signal processing to obtain Solid Earth, 10, 379–390, 2019
382 Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve
Figure 4. Isoseismal map. The epicentral location is in red and
black circles. Red and green dots are suspected amplified or de-
amplified sites (respectively). Blue dots are sites which have MSK
values expected from the attenuation equation (with a 60 % predic-
tion boundary).
the experimental dispersion curve and (c) inversion to esti-
mate Vs30 (Fig. 5). The inverse problem consists of estimat-
ing a set of parameters that describe the soil deposit, based on
an experimental dispersion curve. Inversion problems based
on wave propagation theory cannot be solved in a direct way
due to their non-linearity. Thus, iterative methods must be
used where a theoretical dispersion curve is determined for a
given layer model and compared to the previously obtained
experimental dispersion curve (Ryden et al., 2004). Vs30 typ-
ically does not converge to a single stable value. In other
words, for the same dispersion curve, one will get slightly
different Vs30 depending on the initial model.
Table 1. Acquisition parameters.
Number of geophones 24
Geophone spacing 2–3 m
Array length 46–69 m
Sampling rate 8 kHz
Record length 0.5–2 s
Receivers 4.5 Hz vertical
Source 5 kg hammer
3 Results
We carried out the surveys with a linear array of 24 vertical
geophones (R. T. Clark’s geophones with a natural frequency
of 4.5 Hz) at equal intervals of 2–3 m over a total length of
46–69 m. For the survey sound source, we used a 5 kg sledge-
hammer striking a 20 cm square aluminum plate at variable
offsets of 5, 10, 15, 20, 25 and 30 m (both forward and re-
versed) (Fig. 6a). The seismic data were recorded on a Ge-
ometrics Geode seismograph at a sampling rate mostly of
8 kHz for 0.5–2s (Table 1). For an acceptable signal-to-noise
ratio, we used the so-called “vertical stacking” approach,
which is a summation of multiple synchronized repetitions
of the test (usually five times).
Rayleigh wave dispersion curves are obtained by the
MASW module of the RadExPro®software, whose calcula-
tion procedure is based on a paper by Park et al. (1998), and
also by the WinMASW®software. From all the dispersion
images that we calculated from each offset shot (Fig. 6b), we
chose the smoothest and clearest one (Fig. 6c) to compute the
site’s Vs30 profile. An inversion process then finds the shear-
wave velocity profile whose theoretical dispersion curve is
as close as possible to the experimental curve (Fig. 6d). The
data and coefficients are automatically inverted via genetic
algorithms which represent an optimization procedure be-
longing to the classification of global-search methods. Ge-
netic algorithms are commonly used to generate high-quality
solutions to optimization and search problems by relying on
bio-inspired operators such as mutation, crossover and selec-
tion compared to traditional linear inversion methods based
on gradient methods (Jacobian matrix). These inversion tech-
niques produce a very reliable result in terms of precision and
completeness (Dal Moro et al., 2007).
From 24 surveys, we succeeded in extracting Vs30 for 19
of the 20 sites studied (the Hartuv data were too noisy for
interpretation) (Table 2 and the Supplement). These would
be used to recalibrate the attenuation equation arrived at by
previous investigators at 19 of the 133 sites.
3.1 Velocity model
All ground models were considered to be a stack of hori-
zontal homogeneous elastic layers, neglecting lateral varia-
tions in soil properties. The number of unknowns for a lay-
Solid Earth, 10, 379–390, 2019
Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve 383
Figure 5. Multichannel analysis of surface waves (MASW) technique: (a) acquisition – using a sledgehammer as an artificial source and
a linear array of geophones that receives all wavelets. (b) Signal process – a fundamental mode and first higher mode over the dispersion
image. (c) Inversion – final Vsprofile which best fits the dispersion curve.
ered model, when considering only shear-wave velocity, is
three for each layer: density, thickness and one elastic con-
stant. Therefore, the number of unknowns is 3n1 (where n
represents the number of layers). The change in density with
depth is usually small in comparison to the change in shear
modulus and is normally neglected (Park et al., 1997).
3.2 Number of layers and layer thicknesses
The resolution of surface wave surveys decreases with depth.
Thin layers are well resolved when they are close to the sur-
face, whereas at great depth, the resolution is limited and
only large changes can be detected (Foti et al., 2014). Re-
gardless of the number of the layers at the site, Vs30 is al-
most the same in each case (Fig. 7). For these reasons, as
well as the lack of density information, we did not restrict
each model to a specific number of layers. Without bore-
holes or other direct lithostratigraphic constraint, which is
the case in our work, a useful rule of thumb is to assume
layer thicknesses increasing with depth, to compensate for
the decreased resolution with depth, an intrinsic shortcoming
of surface wave testing (Foti et al., 2014).
3.3 Depth of investigation
We used a 5 kg sledgehammer and summed up five strikes.
For some sites, this type of source is insufficient to deter-
minate a shear-wave profile down to 30 m. In addition, at
some sites, we were not able to spread the geophones at in-
tervals of more than 2 m, which limited the length of the seis-
mic line. This length probably excludes longer wavelengths
which limit the depth of investigation. Lastly, as the shear-
wave velocity of the lowest frequency is higher, more data
are available for deeper layers. Therefore, the penetration
depth will decrease in areas with low shear-wave velocity.
For instance, if we can clearly detect a phase velocity of
about 300 m s1at 5 Hz, we can roughly estimate a depth
of investigation of approximately 20–30m according to the
following equation:
where nranges between 2 and 3 (Foti et al., 2014; Dal Moro,
2014). In other words, this equation emphasizes that the
depth of investigation is about a half to a third of the largest
wavelength observed.
3.4 Recent improvement of the 1927 epicenter
Zohar and Marco (2012) relocated the 1927 epicenter to a
point near the Almog settlement. We used this most recently
published epicenter to calculate new epicentral distances for
the 133 sites. Since Eq. (2) above is dependent upon d, we
checked the variable scatter in the points but found that the
changes in the best-fit coefficients were very minor, so we
assumed for all purposes to use the original. Solid Earth, 10, 379–390, 2019
384 Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve
Figure 6. Data processing with WinMASW®(example from Binyamina): (a) raw data of four different offsets. (b) The four relative dis-
persion images calculated from the raw data. (c) Best dispersion image (offset 15): pink dots are the analyst’s dispersion curve picking. The
blue line and yellow dashed lines are, respectively, the best and the mean curves from the final model. (d) Shear-wave velocity model (blue
profile for the best one and red dashed line is the mean profile from 100 lower rms).
Solid Earth, 10, 379–390, 2019
Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve 385
Table 2. MASW results.
ID Site Vs30 Error Epicentral
(m s1) (%) distance
1 Acre 261 13 131
2 Ashkelon 561 5 89
3 Be’er Sheva 359 8 91
4 Beit HaKerem 1436 12 29
5 Beit Alfa 232 5 79
6 Binyamina 316 5 95
7 Givatayim 396 6 72
8 Hartuv 47
9 Herzliya 330 5 77
10 Jisr al-Majami 294 9 92
11 Lod 1 320 4 60
12 Lod 2 374 6
13 Motza 1 1065 8 33
14 Motza 2 874 8
15 Mt. Scopus 1 600 6 23
16 Mt. Scopus 2 582 5
17 Nahalal 380 7 102
18 Nahariya 883 1 139
19 Peqi’in (Peki’in) 1444 3 131
20 Ramleh (Ramla) 360 4 61
21 Tzemach 1 281 5 101
22 Tzemach 2 273 4
23 Tzora 430 3 50
24 Yavneh (Yavne) 361 10 72
Figure 8 shows a scatter plot of the original MMI (assumed
equivalent to MSK) vs. new dfor their 133 sites. Hough
and Avni (2011) fit these data with a curve whose equa-
tion best describes the attenuation equation for this event.
Using the mathematical form of their curve, we calculated
upper and lower limits such that 60 % of the points are en-
closed. This we call the 60 % prediction boundary. We con-
sider that the lithological effects probably account for much
of the scatter beyond this boundary, due to amplification and
4 Discussion
A number of researchers have studied the 1927 event.
Avni (1999) tried to reduce the impact of local geology and
attempted to generate basic attenuation curves for specific
azimuths. Zohar and Marco (2012) relocated the source po-
sition, while Shani-Kadmiel et al. (2016) studied directivity
of the source pattern. None of these publications address the
Vs30 measurements. An attenuation equation with a term that
depends on the Vs30 index should lead to a better understand-
ing of past events and to more useful predictions of future
Figure 7. Vs30 as a function of a number of layers (example from
Beit Alfa).
Figure 8. Avni’s seismic intensity (MMI) estimates of all the 133
sites. Distance is corrected according to the Zohar and Marco epi-
center. Yellow dots are suspected amplified or de-amplified sites.
Sites with pins are sites where we measured the Vsprofile. Blue
dots are sites which have MMI values expected from the attenua-
tion equation (within the 60 % prediction boundary). Solid Earth, 10, 379–390, 2019
386 Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve
Figure 9. Comparison between our Vs30 results (light blue) and
those calculated from GII’s report (red) (Aksinenko and Hofstetter,
4.1 Survey locations and validation
The decision as to where exactly each survey should take
place was based on Avni’s thesis (1999). Where the location
was not sufficiently known, we rechecked the reference given
by Avni. In most cases, there was evidence of specific dam-
aged buildings. We tried to locate these buildings on histor-
ical maps (1927–1945). Unfortunately, most sites were lo-
cated inside urban areas, where we could not carry out the
seismic surveys. Therefore, we surveyed in nearby open ar-
eas as close as possible to the referenced damage zones.
To validate our results, we compared them with a sum-
mary of thousands of seismic evaluations around Israel car-
ried out over the years by the Geophysical Institute of Israel
(GII) and compiled in a report by Aksinenko and Hofstet-
ter (2012). These evaluations were based upon refraction and
borehole velocity measurements yielding Vsand/or Vpval-
ues, as well as the effects of topography and geology. The
spacing of their data was such that often a number of GII sites
had to be averaged to provide a value within several kilome-
ters for comparison with our MASW values. However, Fig. 9
shows that the GII-based values are in consistent agreement
with those of the MASW. However, this comparison is a bit
tricky because Vs30 results for two sites 5 km or much less
distant could be significantly different, as shown in Fig. 10.
Remembering that Vs30 enters a logarithmic term, we find our
approach potentially useful.
Table 2 lists our 24 sites alphabetically, with their respec-
tive Vs30 values, the computed errors and epicentral distances,
d. The Vs30 values vary from a low of 232m s1in Beit Alfa,
85 ma.s.l. (Fig. 11), in the thick and active alluvial plain of
Figure 10. Comparison between GII’s closest measurements (up to
550 m).
the famous valley of Gilboa some 10 km from the Dead Sea
rift and a site of many millennia of agriculture. The high-
est value is 1444 m s1in Peki’in, 680 m a.s.l. (Fig. 11), in
an area of ancient hillside orchards and massive carbonate
bedrock. On the other hand, the two Motza sites (Fig. 11)
lie in Emek HaArazim (valley of the cedars) on the west-
ern flank of Jerusalem within the massive anticlinorium of
the Judean Hills, at about 570 m a.s.l. Motza 1 (1065m s1)
is on a compacted dirt parking lot above alluvium and the
Soreq Fm., while Motza 2 (874 m s1) is farther up the val-
ley on a gentle hillside above the Beit Meir Fm. Both are of
similar limestone and marl composition and Cretaceous age.
4.2 A new attenuation equation
In the present case of the 1927 earthquake, the sources of
the data are mostly historical documents and not strong data
measurements. This makes it difficult to quantify site re-
sponse into a single equation. In the practical modern attenu-
ation relationship, Vs30 is a crucial index. A term that depends
on Vs30 has previously been constrained for several large data
sets (Abrahamson et al., 2014; Boore et al., 1997; Camp-
bell and Bozorgnia, 2008). We chose the Boore et al. (1997)
attenuation equation (Eq. 4) in order to emphasize site re-
ln(Y)=b1+b2(M6)+b3(M 6)2+b5
ln(r)+bvln Vs
where Yis the ground-motion variable (peak horizontal ac-
celeration or pseudo-acceleration response in g), Mis the
Solid Earth, 10, 379–390, 2019
Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve 387
Figure 11. Three of the sites investigated: (a) Motza 1, (b) Motza 2 and (c) Peki’in. Black lines represent the seismic line location. (d) The
locations of the sites over a 25 m DTM image (Hall, 2008). Also shown are sites mentioned in the text: Jerusalem (J) and Emek HaArazim
moment magnitude, ris the epicentral distance in kilometers,
and VAand all bterms are frequency-dependent coefficients
to be determined. By adding Boore et al.’s (1997) Vsterm to
the Hough and Avni (2011) attenuation equation (Eq. 2), we
suggest a new equation for the region:
MMI = −0.64 +1.7M0.00448d1.67
log(d)+C4ln Vs30
where VAand C4are adjustable coefficients. The first four
coefficients remain the same as we assert that the magni-
tude, attenuation, geometrical spreading and site response
are all independent. We adopt the value of VAfrom Boore
et al.’s (1997) equation (Eq. 4), as it represents a single
value independent of the frequency. We took formerly de-
rived GMPE, with its coefficients, and added another term,
by regressing only for the new coefficient, then optimizing
C4and VAby least squares fitting (LSF), as shown in Fig. 12;
we get the final equation:
MMI = −0.64 +1.7M0.00448d1.67
log(d)2.1ln Vs30
655 .(6)
Figure 12. A sensitivity analysis for calibration of the new equation.
4.3 The performance of the new attenuation equation
With these coefficients, 58%, or 11 of 19 sites, were am-
plified or de-amplified as we expected. For the entire dis-
tance range (up to 250 km), the Vs30 corrections leave 42 %
of sites out of the prediction boundary (8 of 19 sites). Seis-
mic intensities at all eight sites are overpredicted by the at-
tenuation equation (Eq. 2) (Fig. 13). We expect that Vs30 at
these sites will be higher than 655 m s1in order to obtain Solid Earth, 10, 379–390, 2019
388 Y. Darvasi and A. Agnon: Recalibration of Dead Sea region attenuation curve
Figure 13. Site response corrections: yellow dots are MMI before
site correction, and black dots, with error bars due to Vsuncertainty,
represent the MMI after reducing site effects.
de-amplification. However, our results show the opposite ef-
fect – these eight sites are characterized by lower Vs30, which
drives amplification. This can be caused by the fact that mea-
surements were taken over agricultural fields, of which the
upper layers (the first few meters) are characterized by low
shear-wave velocity, decreasing the average Vs. Another rea-
sonable explanation is that we did not succeed in extracting
the average shear-wave velocity down to 30m and perhaps
we missed some high-velocity shear-wave layers in deeper
layers. In such cases, we constrain the last layer to be thicker
in order to estimate Vs30 for all our surveys.
5 Conclusions
In this research, we investigate site amplification and de-
amplification around Israel. According to previous studies
(Aki, 1988; Boore, 2003; Borcherdt, 1994; Field and Jacob,
1995; Joyner and Boore, 1988), the local lithology can am-
plify or de-amplify wave amplitude. The commonly used
modern seismic method – MASW – allowed the extraction
of Vsprofiles at 19 sites reportedly damaged by the 1927
6.2 MLearthquake. We use these profiles to update the at-
tenuation equation for the Dead Sea region by including the
Vs30 term.
According to this new equation, 11 sites, which constitute
58 % of our measured samples, move into the 60 % predic-
tion boundary. This suggests that the prediction boundary ac-
tually encompasses over 80 % of the macroseismic observa-
tions. This fit is better than any available attenuation equa-
tion for the Dead Sea region. However, as we have used
only 19 sites, we should consider further research and pro-
vide wider results. Although our final equation (Eq. 6) shows
amplification and de-amplification depending on Vs30 , it does
not take into consideration any other factor, such as building
quality, foundation depth, topography, earthquake directiv-
ity, type of fault, etc. Obviously, for better results, we must
use additional methods and jointly invert some other seismic
data such as refraction (S and P waves), horizontal-to-vertical
spectral ratio (HVSR), MASW of the transverse component
of Love waves, MASW of the radial component of Rayleigh
wave, extended spatial autocorrelation (ESAC), etc. Also,
with these data in hand, a full inversion for the epicenter will
be in order.
Despite the scarcity of data, this is the first time that an
integration of historical data with shear-wave velocity profile
measurements improved the attenuation relation. In order to
better estimate the peak ground acceleration or the seismic
intensities that will be caused by future earthquakes, attenu-
ation relations are necessary for areas characterized by high
seismicity. Some of the regions of low-to-moderate seismic-
ity have rich sources of historical earthquake data. The in-
tegration of historical data with modern shear-wave velocity
profile measurements will lead to a better understanding of
future earthquakes.
Data availability. The entire database of the Vsmeasurements
can be found at
(Davarsi and Agnon, 2019).
Supplement. The supplement related to this article is available
online at:
Competing interests. The authors declare that they have no conflict
of interest.
Special issue statement. This article is part of the special issue
“Environmental changes and hazards in the Dead Sea region
(NHESS/ACP/HESS/SE inter-journal SI)”. It is not associated with
a conference.
Acknowledgements. We thank the Neev Center for Geoinfomat-
ics’s facilities and its students. We are especially grateful to John
K. Hall, founder of the Center, for his ongoing support. We are
grateful to the Helmholtz Association of German Research Centers
for funding this research. We thank Moshe Reshef for comments
and suggestions on an earlier draft and Ran Bachrach for valuable
advice. We acknowledge the contribution of Michael Weber and
the geophysical deep sounding section at GFZ. Finally, we thank
Amit Ronen for his assistance.
Edited by: Charlotte Krawczyk
Reviewed by: two anonymous referees
Solid Earth, 10, 379–390, 2019
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... We apply three empirical attenuation relations (28-31) developed for the Dead Sea region to constrain the lower magnitude limit of paleoseismic events that the ICDP Core 5017-1 records (Materials and Methods). Among them, two attenuation relations (28)(29)(30) are described by macroseismic intensity, magnitude, and epicentral distance (D), and one relation (31) is described by peak ground acceleration (PGA), magnitude, and epicentral distance. To apply the two attenuation relations that are described by seismic intensity, we convert accelerations into seismic intensity via the linear relationships between PGA and the modified Mercalli intensity scale (MMI) that Wald et al. (32) proposed (table S2). ...
... The ICDP Core 5017-1 records 139 strong seismic shaking events with PGA ≥ 0.34g (MMI ≥ VIII) (table S2). According to the regional empirical attenuation relations (28)(29)(30)(31), one felt intensity, for example, MMI ≥ VIII (PGA ≥ 0.34g) at the drill site, will require a moderate earthquake (6.0 < M w < 7.0) with a D between 5 and 30 km, an M w ≥ 7.0 earthquake with a D of 30 km, or an M w ≥ 8.0 earthquake with a D of up to 150 km. We adopt a maximum magnitude in the region of M w 8.0, which will require a rupture of ~300 km along a major fault. ...
... We applied all these three empirical attenuation relations (28,30,31) to constrain the lower magnitude limit of paleoseismic events recorded in the ICDP Core 5017-1. The attenuation relation of Malkawi and Fahmi (28) is more suitable for the inverting point intensity of strong seismic shaking events (MMI ≥ IX) to magnitude than the others. ...
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Large earthquakes (magnitude ≥ 7.0) are rare, especially along slow-slipping plate boundaries. Lack of large earthquakes in the instrumental record enlarges uncertainty of the recurrence time; the recurrence of large earthquakes is generally determined by extrapolation according to a magnitude-frequency relation. We enhance the seismological catalog of the Dead Sea Fault Zone by including a 220,000-year-long continuous large earthquake record based on seismites from the Dead Sea center. We constrain seismic shaking intensities via computational fluid dynamics modeling and invert them for earthquake magnitude. Our analysis shows that the recurrence time of large earthquakes follows a power-law distribution, with a mean of 1400 ± 160 years. This mean recurrence is notable shorter than the previous estimate of 11,000 years for the past 40,000 years. Our unique record confirms a clustered earthquake recurrence pattern and a group-fault temporal clustering model, and reveals an unexpectedly high seismicity rate on a slow-slipping plate boundary.
... Elements of stratigraphy are dated using published literature, available inscriptions, and the interpretation of radiocarbon data. (Hough and Avni, 2009), taking into consideration site amplification conditions (Darvasi and Agnon, 2019). ...
... To discuss potential causative relationships to candidate earthquakes, where observed EAEs produced a minimum seismic intensity of VIII-IX in the theater, an attempt was made to constrain the candidate events, based on expected earthquake MMI intensities using a calibrated intensity-based attenuation model of the Dead Sea, as proposed by Hough and Avni (2009), and recently developed by Darvasi and Agnon (2019) to incorporate site-specific conditions (equation 1). The model includes information related to site-specific conditions (i.e., shear-wave velocity), local magnitude, and epicentral distances: in which MMI is the modified Mercalli intensity, M L is the local magnitude, d is the distance from the epicenter, and V S30 represents the average shear-wave velocity from the surface to a depth of 30 m. ...
... The corresponding location of epicenter is marked in Figure 13. * Estimated intensity using Darvasi and Agnon (2019), V S30 800 m=s. † Estimated intensity using Darvasi and Agnon (2019), V S30 360 m=s. ...
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... The magnitude (size) was determined to be M6.2 and the epicenter (focus) was located to the north of the Dead Sea [37,38] (Figure 1). The wealth of information regarding this event includes professional reports [39][40][41][42], popular sources and newspapers [43][44][45][46][47][48], letters, documents, accounts [49,50], and photographs [51,52] as well as scientific studies [53][54][55][56][57][58][59][60]. This earthquake is unique for being the first destructive seismic event in the region that was described in numerous historical accounts [36] while also being recorded by seismographs [57]. ...
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It is impossible to prevent earthquakes but it is possible to mitigate the related effects and to reduce the loss of life, injuries and damages associated with the disastrous earthquakes. Eventually, earthquakes may generate many more disasters such as liquefaction, landslides, earth ruptures and most prominently ground vibrations which in turn may accompany the collapse of non-earthquake-resistant buildings resulting in massive loss of life and property. Therefore, it is essential to substantiate the effects of earthquakes along with the existing structural design codes. The assessment of the earthquake response analysis for the earthquakes that occurred beneath NW, Central and NE Himalayan regions of India symbolised the normalised spectral amplifications for various categories of the sites exposed on hard rock, sediments and alluvium. It has been observed that the hard strata prominently exhibit a lower spectral acceleration than that of the alluvium sites for NW, Central and NE Himalayan regions for different kinds of site conditions and regional geological formations. The comparison of spectral acceleration and corresponding predominant period with that of the design code given by the Bureau of Indian Standard (BIS) design code demonstrates the efficacy of the BIS code which may be strictly implemented for both urban as well as rural Himalayan and adjoining regions of India as the estimated response curves from actual earthquakes for all the sites fall within the structural limits proposed by BIS code. As a conclusive remark, it is stated that BIS-based structural design codes may provide safety to the structures in case of earthquake shaking in and around the Himalayan region of India. It is also inferred that the use of an appropriate building design code that considers the constraints of the response spectrum and related predominant period may have the potential to reduce the loss of life and property in case of Himalayan disastrous earthquakes. Moreover, it is also imperative to design an earthquake risk resilient society to mitigate imminent plausible seismic hazards originating in the detachment zone of the Himalayan Frontal Thrust system.KeywordsResponse analysisSpectral accelerationGround motionBISEarthquake risk resilient
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ABSTRAK Secara geologi, wilayah Cekungan Bandung tersusun oleh endapan danau Bandung purba yang terdiri atas lapisan lempung dengan sisipan lapisan pasir sehingga rentan terhadap likuifaksi akibat gempa bumi. Metode analisis multi-sensor gelombang permukaan (MASW) adalah salah satu metode geofisika yang menghasilkan model satu dimensi kecepatan gelombang geser (Vs) terhadap kedalaman. Makalah ini menyajikan hasil analisis potensi likuifaksi menggunakan data profil Vs di 5 lokasi yang tersebar di wilayah Cekungan Bandung. Data Vs diperoleh dengan menggunakan 24 geophone yang tersebar dengan spasi 4 meter di setiap lokasi penelitian. Hasil analisis data menggunakan metode MASW menghasilkan profil Vs dan Vs30 di setiap lokasi yang menunjukkan bahwa lapisan tanah di wilayah Cekungan Bandung dapat diklasifikasi dalam kelas situs E dan D. Sedangkan berdasarkan hasil analisis potensi likuifaksi menggunakan profil Vs, dengan mempertimbangkan percepatan tanah puncak yang dihasilkan oleh Sesar Lembang (M w 6,5), mengindikasikan bahwa lapisan pasir di dalam endapan danau purba mempunyai potensi likuifaksi pada kedalaman dan ketebalan yang bervariasi. Lapisan pasir dengan nilai Vs < 175 m/detik yang menyebabkan potensi likuifaksi di daerah Bojongemas lebih tinggi dibandingkan dengan daerah lainnya. Hasil penelitian ini menunjukkan kesesuaian dengan hasil analisis likuifaksi berdasarkan metode uji penetrasi standar dari hasil penelitian terdahulu. Kata kunci: gelombang permukaan, kelas situs, kecepatan gelombang geser, likuifaksi, MASW ABSTRACT − The Evaluation of Liquefaction Potential in Bandung Basin Area Based on Multi-Channel Analysis of Surface Wave. The Bandung Basin region is composed of ancient Bandung lake sediment deposits consisting of thick clay layers intercalated with sand layers, which is vulnerable to liquefaction due to earthquakes. The Multi-channel Analysis of Surface Wave (MASW) analysis method is a geophysical method that produces a one-dimensional model of shear wave velocity (Vs) against depth. This paper presents the results of an analysis of the potential for liquefaction using Vs profile data at 5 locations spread across the Bandung Basin. using 24 geophones with 4-m spacing. The results of data analysis using the MASW method produce Vs and Vs30 profiles at each location which indicate that the soil layers in the Bandung Basin area can be classified into E and D site classes. Meanwhile, based on the results of the analysis of potential liquefaction using the Vs profile, taking into account the peak soil acceleration produced by the Lembang Fault (Mw 6.5), indicates that the sand layer in ancient lake sediment deposits has the potential for liquefaction at varying depths and thicknesses. Sand layer with a value of Vs <175 m / sec which causes the potential for liquefaction in the Bojongemas area is higher than in the other areas. The results of this study confirm liquefaction analysis based on the standard penetration test method from the previous study.
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We develop a generic finite-fault source model for simulation of large earthquakes: the distributed slip model (DSM). Six geometric and seven kinematic parameters are used to describe a smooth pseudo-Gaussian slip distribution, such that slip decays from peak slip within an elliptical rupture patch to zero at the borders of the patch. The DSM is implemented to initiate seismic-wave propagation in a finite-difference code. Radiation pattern and spectral characteristics of the DSM are compared with those of commonly used finite-fault models, that is, the classical Haskell's model (HM) and the modified HM with radial rupture propagation (HM-RRP). The DSM accounts for directivity effects in the fault-parallel direction, as well as fault-normal ground motions, and overcomes the unrealistic uniform slip and stress singularities of the Haskell-type models. We show the potential of the DSM to estimate the ground motions of strong earthquakes. We use this model to initiate seismic-wave propagation during the 1927 M-L 6.25 Jericho earthquake and compare calculated macroseismic intensities to reported intensities at 122 localities. The root mean square of intensity residuals is 0.68, with 56% of the calculated intensities matching the reported intensities and 98% of the calculated intensities within a single unit from the reported intensities. The DSM is an essential step toward robust ground-motion prediction in earthquake-prone regions with a long return period and limited instrumental coverage. Online Material: Animation of rupture and wave propagation.
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Results of seismologic studies conducted by the U.S. reconnaissance team in conjunction with Soviet colleagues following the tragic earthquakes of December 7, 1988, suggest that site conditions may have been a major factor in contributing to increased damage levels in Leninakan. As the potential severity of these effects in Leninakan had not been previously identified, this chapter presents results intended to provide a preliminary quantification of these effects on both damage and levels of ground motion observed in Leninakan. The article describes the damage distribution geologic setting, ground motion amplification in Leninakan, including analog amplifications and spectral amplifications. Preliminary model estimates for site response are presented. It is concluded that ground motion amplification in the 0.5-2.5-second period range was a major contributing factor to increased damage in Leninakan as compared with Kirovakan. Leninakan is located on thick water saturated alluvial deposits.
This book examines historical evidence from the last 2000 years to analyze earthquakes in the eastern Mediterranean and Middle East. Early chapters review techniques of historical seismology, while the main body of the book comprises a catalog of more than 4000 earthquakes identified from historical sources. Each event is supported by textual evidence extracted from primary sources and translated into English. Covering southern Romania, Greece, Turkey, Lebanon, Israel, Egypt, Jordan, Syria, and Iraq, the book documents past seismic events, places them in a broad tectonic framework, and provides essential information for those attempting to prepare for, and mitigate the effects of, future earthquakes and tsunamis in these countries. This volume is an indispensable reference for researchers studying the seismic history of the eastern Mediterranean and Middle East, including archaeologists, historians, earth scientists, engineers and earthquake hazard analysts. A parametric catalog of these seismic events can be downloaded from