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1.
A moderate-sized (Mw  5.3) earthquake occurred in the Dead Sea basin on February 11, 2004. A rigorous seismological analysis of the main shock and numerous aftershocks suggests that seismogenic structure was a secondary, antithetic fault within the Dead Sea fault system. The main shock is well located using all available regional seismic stations, and 43 aftershocks were precisely located relative to the main shock using a double difference algorithm. The first motion, focal mechanism for this earthquake demonstrates NNW–SSE and ENE–WSW striking nodal planes, and the aftershocks distribution is consistent with the latter — indicating a right-lateral sense of displacement. This orientation and sense of shear are consistent with similarly oriented geological faults around the Dead Sea basin — these structures are likely antithetic faults within the transform system. Although moderate in size, earthquakes that occur very close to the large Dead Sea fault system warrant consideration in the earthquake hazard assessment of the region: For example, owing to the proximity to the main fault, moderate earthquakes such as this may produce static changes in Coulomb stress along the main fault.  相似文献   

2.
The Dead Sea basin is often cited as one of the classic examples for the evolution of pull-apart basins along strike–slip faults. Despite its significance, the internal structure of the northern Dead Sea basin has never been addressed conclusively. In order to produce the first comprehensive, high-resolution analysis of this area, all available seismic data from the northern Dead Sea (lake)–lower Jordan valley (land) were combined. Results show that the northern Dead Sea basin is comprised of a system of tectonically controlled sub-basins delimited by the converging Western and Eastern boundary faults of the Dead Sea fault valley. These sub-basins grow shallower and smaller to the north and are separated by structural saddles marking the location of active transverse faults. The sedimentary fill within the sub-basins was found to be relatively thicker than previously interpreted. As a result of the findings of this study, the “classic” model for the development of pull-aparts, based on the Dead Sea, is revised. The new comprehensive compilation of data produced here for the first time was used to improve upon existing conceptual models and may advance the understanding of similar basinal systems elsewhere.  相似文献   

3.
A Probabilistic method is used to evaluate the seismic hazard of nineteen embankment dam sites in Jordan. A line source model developed by McGuire (1978) is used in this study. An updated earthquake catalogue covering the period from 1 A.D. to 1991 A.D. is used for this purpose. This catalogue includes all earthquakes that occurred in Jordan and adjacent areas, more specifically between latitudes 27.0°–35.5° N and longitudes 32.0°–39.0° E.Nine distinct seismic sources of potential seismic activities are identified. The seismic hazard parameters are determined using the method suggested by Kijko and Sellevoll (1989).The Peak Ground Acceleration (PGA) is selected as a measure of ground motion severity. Esteva (1974) attenuation relationship is used in evaluating PGA values at each dam site. Analysis is carried out for 50%, 90%, and 95% probability that is not being exceeded in a life time of 50, 100, and 200 years.Results of analysis indicate that PGA values are higher for dam sites closer to the Dead Sea Fault. This fault is believed to be responsible for most earthquake activities in Jordan and vicinity. The highest PGA value is found to be for Al-Karama dam site.  相似文献   

4.
Recently released reflection seismic lines from the Eastern side of the Jordan River north of the Dead Sea were interpreted by using borehole data and incorporated with the previously published seismic lines of the eastern side of the Jordan River. For the first time, the lines from the eastern side of the Jordan River were combined with the published reflection seismic lines from the western side of the Jordan River. In the complete cross sections, the inner deep basin is strongly asymmetric toward the Jericho Fault supporting the interpretation of this segment of the fault as the long-lived and presently active part of the Dead Sea Transform. There is no indication for a shift of the depocenter toward a hypothetical eastern major fault with time, as recently suggested. Rather, the north-eastern margin of the deep basin takes the form of a large flexure, modestly faulted. In the N–S-section along its depocenter, the floor of the basin at its northern end appears to deepen continuously by roughly 0.5 km over 10 km distance, without evidence of a transverse fault. The asymmetric and gently-dipping shape of the basin can be explained by models in which the basin is located outside the area of overlap between en-echelon strike-slip faults.  相似文献   

5.
Several source parameters (source dimensions, slip, particle velocity, static and dynamic stress drop) are determined for the moderate-size October 27th, 2004 (MW = 5.8), and the large August 30th, 1986 (MW = 7.1) and March 4th, 1977 (MW = 7.4) Vrancea (Romania) intermediate-depth earthquakes. For this purpose, the empirical Green's functions method of Irikura [e.g. Irikura, K. (1983). Semi-Empirical Estimation of Strong Ground Motions during Large Earthquakes. Bull. Dis. Prev. Res. Inst., Kyoto Univ., 33, Part 2, No. 298, 63–104., Irikura, K. (1986). Prediction of strong acceleration motions using empirical Green's function, in Proceedings of the 7th Japan earthquake engineering symposium, 151–156., Irikura, K. (1999). Techniques for the simulation of strong ground motion and deterministic seismic hazard analysis, in Proceedings of the advanced study course seismotectonic and microzonation techniques in earthquake engineering: integrated training in earthquake risk reduction practices, Kefallinia, 453–554.] is used to generate synthetic time series from recordings of smaller events (with 4 ≤ MW ≤ 5) in order to estimate several parameters characterizing the so-called strong motion generation area, which is defined as an extended area with homogeneous slip and rise time and, for crustal earthquakes, corresponds to an asperity of about 100 bar stress release [Miyake, H., T. Iwata and K. Irikura (2003). Source characterization for broadband ground-motion simulation: Kinematic heterogeneous source model and strong motion generation area. Bull. Seism. Soc. Am., 93, 2531–2545.] The parameters are obtained by acceleration envelope and displacement waveform inversion for the 2004 and 1986 events and MSK intensity pattern inversion for the 1977 event using a genetic algorithm. The strong motion recordings of the analyzed Vrancea earthquakes as well as the MSK intensity pattern of the 1977 earthquake can be well reproduced using relatively small strong motion generation areas, which corresponds to small asperities with high stress drops (300–1200 bar) and high particle velocities (3–5 m/s). These results imply a very efficient high-frequency radiation, which has to be taken into account for strong ground motion prediction, and indicate that the intermediate-depth Vrancea earthquakes are inherently different from crustal events.  相似文献   

6.
We study the Byzantine-to-Ummayad (6th–8th century) archaeological site of Umm-El-Qanatir, located 10 km east of the Dead Sea Transform (DST) in northern Israel. The site was damaged by an earthquake-induced landslide, and in this work we use slope stability analysis to constrain the historical seismic acceleration that occurred along the northern segment of the DST. Umm-El-Qanatir archaeological site is located on a slope of a canyon and contains evidence for earthquake-related damage, including fallen columns and walls, horizontal shift of heavy masonry blocks, and complete burial of ceramic pots and farming tools beneath fallen ceilings. A water pool that collected spring water is displaced nearly one meter by the landslide. The artifacts from the village and the spring area indicate that people inhabited the site until the middle of the 8th century. We argue that the destruction, which forced the abandonment of Umm-El-Qanatir together with nearby settlements, was associated with the earthquake of January 18, 749 CE. In order to evaluate the ground acceleration related to the above earthquake, we back-analyze the stability of a failed slope, which cut and displaced the water-pool, using slope stability software (Slope/W). The results show that the slope is statically stable and that high values of horizontal seismic acceleration (>0.3 g) are required to induce slope failure. Subsequently, we use the Newmark displacement method to calculate the earthquake magnitude needed to cause the slope failure as a function of distance from the site. The results (attributed to the 749 CE earthquake) show that a MW > 7.0 earthquake up to 25 km from the site could have induced the studied landslide.  相似文献   

7.
Saudi Arabia is characterized as largely aseismic; however, the tectonic plate boundaries that surround it are very active. To improve characterization of seismicity and ground motion hazard, the Saudi Arabian Digital Seismic Network (SANDSN) was installed in 1998 and continues to be operated by the Saudi Geological Survey (SGS) and King Abdulaziz City for Science and Technology (KACST). This article describes research performed to improve seismic hazard parameters using earthquake location and magnitude calibration of the high-quality SANDSN data. The SANDSN consists of 38 seismic stations, 27 broadband, and 11 short period. All data are telemetered in real time to a central facility at KACST in Riyadh. The SANDSN stations show low background noise levels and have good signal detection capabilities; however, some stations show cultural noise at frequencies above 1.0 Hz. We assessed the SANDSN event location capabilities by comparing KACST locations with well-determined locations derived from ground truth or global observations. While a clear location bias exists when using the global average iasp91 earth model, the locations can be improved by using regional models optimized for different tectonic source regions. The article presents detailed analysis of some events and Dead Sea explosions where we found gross errors in estimated locations. New velocity models we calculated that should improve estimated locations of regional events in three specific regions include (1) Gulf of Aqabah—Dead Sea region, (2) Arabian Shield, and (3) Arabian Platform. Recently, these models were applied to the SANDSN to improve local and teleseismic event locations and to develop an accurate magnitude scale for Saudi Arabia. The Zagros Thrust presents the most seismic hazard to eastern Saudi Arabia because of the frequent occurrence of earthquakes. Although these events are 200 km or further from the Arabian coast, wave propagation through sedimentary structure of the Gulf causes long-duration ground motions for periods between 3 and 10 s. Such ground motions could excite response in large engineered structures (e.g., tall buildings and long bridges) such as was experienced after the November 22, 2005 Qeshm Island earthquake off the southern coast of Iran.  相似文献   

8.
The southernmost sector of the Italian peninsula is crossed by an almost continuous seismogenic belt capable of producing M ∼ 7 earthquakes and extending from the Calabrian Arc, through the Messina Straits, as far as Southeastern Sicily. Though large earthquakes occurring in this region during the last millennium are fairly well known from the historical point of view and seismic catalogues may be considered complete for destructive and badly damaging events (IX ≤ I o ≤ XI MCS), the knowledge and seismic completeness of moderate earthquakes can be improved by investigating other kinds of documentary sources not explored by the classical seismological tradition. In this paper, we present a case study explanatory of the problem, regarding the Ionian coast between the Messina Straits and Mount Etna volcano, an area of North-eastern Sicily lacking evidence of relevant seismic activity in historical times. Now, after a systematic analysis of the 18th century journalistic sources (gazettes), this gap can be partly filled by the rediscovery of a seismic sequence that took place in 1780. According to the available catalogues, the only event on record for this year is a minor shock (I o = VI MCS, M w = 4.8) recorded in Messina on March 28, 1780. The newly discovered data allow to reinstate it as the mainshock (I o = VII–VIII MCS, M w = 5.6) of a significant seismic period, which went on from March to June 1780, causing severe damage along the Ionian coast of North-eastern Sicily. The source responsible for this event appears located offshore, 40-km south of the previous determination, and is consistent with the Taormina Fault suggested by the geological literature, developing in the low seismic rate zone at the southernmost termination of the 1908 Messina earthquake fault.  相似文献   

9.
GPS systems can be used as seismometers by sampling ground positions to detect travelling seismic waves. Data from dense geodetic networks near large earthquakes have been used to improve magnitude estimates, for tsunami warning, and to better understand the rupture processes. Here, we present 1 Hz GPS records of the March 11th, 2011, Mw = 9.0 Tohoku earthquake at unprecedented teleseismic distances. The spatial and temporal variations of the three‐dimensional GPS displacement vector field show various body waves, Love and Rayleigh surface waves along the direct path, and Love waves from the more than 31 000 km long major arc path. These results suggest that seismic wavefields can be mapped at teleseismic distances globally using space geodesy and could thus be used for source and structural studies. Data from numerous real‐time kinematic GPS networks could be combined to show the displacement field, giving unparalleled views of Earth's response to large earthquakes.  相似文献   

10.
The Dead Sea Basin is a morphotectonic depression along the Dead Sea Transform. Its structure can be described as a deep rhomb-graben (pull-apart) flanked by two block-faulted marginal zones. We have studied the recent tectonic structure of the northwestern margin of the Dead Sea Basin in the area where the northern strike-slip master fault enters the basin and approaches the western marginal zone (Western Boundary Fault). For this purpose, we have analyzed 3.5-kHz seismic reflection profiles obtained from the northwestern corner of the Dead Sea. The seismic profiles give insight into the recent tectonic deformation of the northwestern margin of the Dead Sea Basin. A series of 11 seismic profiles are presented and described. Although several deformation features can be explained in terms of gravity tectonics, it is suggested that the occurrence of strike-slip in this part of the Dead Sea Basin is most likely. Seismic sections reveal a narrow zone of intensely deformed strata. This zone gradually merges into a zone marked by a newly discovered tectonic depression, the Qumran Basin. It is speculated that both structural zones originate from strike-slip along right-bending faults that splay-off from the Jordan Fault, the strike-slip master fault that delimits the active Dead Sea rhomb-graben on the west. Fault interaction between the strike-slip master fault and the normal faults bounding the transform valley seems the most plausible explanation for the origin of the right-bending splays. We suggest that the observed southward widening of the Dead Sea Basin possibly results from the successive formation of secondary right-bending splays to the north, as the active depocenter of the Dead Sea Basin migrates northward with time.  相似文献   

11.
During two distinct earthquakes occurred on March 7, 1867 and October 6, 1944, tsunami waves were also observed at some localities around the Gulf of Edremit, NE Aegean Sea. The first event (M w = 6.8) mostly affected the city of Mitilini of Lesvos Island while the Gulf of Edremit-Ayvacık earthquake (M S = 6.8) largely affected the northern and eastern coastal areas of the Gulf of Edremit. In 1944 earthquake, numerous surface cracks and water gushes were reported. The coastal neighborhoods of the town of Ayvalık in the east were flooded by tsunami waves. At the WSW extend of the main fault observed on land, which is parallel to the present-day slip vectors, some normal-oblique faults were observed close and subparallel to the northern coast. On the basis of historical documents, reports, interviews, geological setting, field observations and marine seismic reflection data, the 1944 earthquake was not triggered by one of the main fault segments but by a secondary fault or fault group which was described in this study. Depending on the distribution of tensional and compressional forces in the region, which rotates clockwise under the control of the middle strand of the North Anatolian fault, secondary fault groups become important. The moment tensor parameters of such small-size events have been determined and have obtained consistent results with the faults proposed in this study.  相似文献   

12.
《International Geology Review》2012,54(10):1219-1228
This article examines a report in the 27th chapter of the Gospel of Matthew in the New Testament that an earthquake was felt in Jerusalem on the day of the crucifixion of Jesus of Nazareth. We have tabulated a varved chronology from a core from Ein Gedi on the western shore of the Dead Sea between deformed sediments due to a widespread earthquake in 31 BC and deformed sediments due to an early first-century earthquake. The early first-century seismic event has been tentatively assigned a date of 31 AD with an accuracy of ±5 years. Plausible candidates include the earthquake reported in the Gospel of Matthew, an earthquake that occurred sometime before or after the crucifixion and was in effect ‘borrowed’ by the author of the Gospel of Matthew, and a local earthquake between 26 and 36 AD that was sufficiently energetic to deform the sediments at Ein Gedi but not energetic enough to produce a still extant and extra-biblical historical record. If the last possibility is true, this would mean that the report of an earthquake in the Gospel of Matthew is a type of allegory.  相似文献   

13.
Seismicity of Sinai Peninsula, Egypt   总被引：1，自引：1，他引：0  
The Sinai Peninsula has a triangular shape between the African and Arabian Plates and is bounded from the western and eastern borders by the Gulf of Suez and Gulf of Aqaba–Dead Sea rift systems, respectively. It is affected by strong and destructive earthquakes (e.g., March 31, 1969 and November 22, 1995) and moderate earthquakes (m b?>?5) throughout its history. After the installation of the Egyptian National Seismic Network (ENSN), a great number of earthquakes has been recorded within and around Sinai. Consequently, the seismogenic source zones and seismotectonic behavior can be clearly identified. Available data, including both historical and instrumental (1900–1997), have been collected from national and international data centers. While the data from 1998 till December 2007 are gathered from ENSN bulletins. The seismogenic source zones that might affect Sinai Peninsula are defined more precisely in this work depending on the distribution of earthquakes, seismicity rate (a value), b value, and fault plane solution of the major earthquakes. In addition, the type of faults prevailed and characterized these zones. It is concluded that the Gulf of Aqaba zone–Dead Sea transform zone, Gulf of Suez rift zone, Cairo–Suez District zone, and Eastern Mediterranean dislocation zone represent the major effective zones for Sinai. Furthermore, there are two local seismic zones passing through Sinai contributing to the earthquake activities of Sinai, these are the Negev shear zone and Central Sinai fault (Themed fault) zone. The source parameters, a and b values, and the maximum expected moment magnitude have been determined for each of these zones. These results will contribute to a great extent in the seismic hazard assessment and risk mitigation studies for Sinai Peninsula to protect the developmental projects.  相似文献   

14.
The Elat fault (a segment of the Dead Sea Transform) runs along the southern Arava valley (part of the Dead Sea Rift, Israel) forming a complex fault zone that displays a time-dependent seismic behaviour. Paleoseismic evidence shows that this fault zone has generated at least 15 earthquakes of magnitude larger than M 6 during the late Pleistocene and the Holocene. However, at present the Elat fault is one of the quietest segments of the Dead Sea Transform, lacking even microsesimicity. The last event detected in the southern Arava valley occurred in the Avrona playa and was strong enough to have deformed the playa and to change it from a closed basin with internal drainage into an open basin draining to the south.Paleoseismological, geophysical and archaeological evidences indicate that this event was the historical devastating earthquake, which occurred in 1068 AD in the eastern Mediterranean region. According to the present study this event was strong enough to rupture the surface, reactivate at least two fault branches of the Elat fault and vertically displace the surface and an early Islamic irrigation system by at least 1 m. In addition, the playa area was uplifted between 2.5 and 3 m along the eastern part of the Elat fault shear zone. Such values are compatible with an earthquake magnitude ranging between M 6.6 and 7. Since the average recurrence interval of strong earthquakes during the Holocene along the Elat fault is about 1.2 ± 0.3 ky and the last earthquake occurred more about 1000 years ago, the possibility of a very strong earthquake in this area in the future should be seriously considered in assessing seismic hazards.  相似文献   

15.
Opening of the Red Sea is accompanied by convergence between the Arabian plate and Eurasia. Regional topography and structure favour gravity glide as the main driving force of plate translation. At the leading edge of the plate, the Zagros Mountains undergo coseismic serial folding which is equivalent to Holocene shortening by ∼20 mm/year and which has led to major episodes of coastal uplift of which the last was ∼1700 years BP. At the Jordan Rift transform, which bounds the Arabian plate on the west, a recurrence interval of ∼1600 years is reported for events of ML≥5.5. The palaeomagnetic record for the last 3.2 Ma indicates an average spreading rate for the Red Sea of ∼20 mm/year; there is some evidence that hydrothermal activity in the Red Sea is pulsatory, with a period of ∼2000 year, and that it reflects discontinuous spreading. The Holocene neotectonic records of the Zagros, the Jordan Rift and the Red Sea are the product of complex plate interactions and of the accumulation and release of strain in the crust along the plate margins. But they also reflect elastic strain energy storage and release within the Arabian plate, whence parallels in the period of major deformation episodes in the three deforming zones and the apparent discrepancy between the seismic moment predicted by plate kinematics and that recorded in the Zagros. Any associated intraplate deformation, if detected geodetically, would thus help the assessment of seismic hazard.  相似文献   

16.
We estimated spatio-temporal evolution of Coulomb stress within the subducted Pacific slab in Hokkaido from the analysis of seismicity rate change. For this purpose we used earthquake catalog from the Institute of Seismology and Volcanology (ISV), Hokkaido University for the period 1993/4/1–2006/12/31 after relocating to compensate location errors due to the heterogeneous P- and S-wave structure beneath Hokkaido. We found that spatial pattern of Coulomb stress change inverted from the seismicity rate change is comparable with static change in Coulomb stress estimated from dislocation models. Our results and analyses reveal important insights on spatio-temporal pattern of deformation of the subducted Pacific slab in terms of Coulomb stress change. We found that the 2003 Tokachi Oki earthquake (Mw = 8.0) pervasively perturbed Coulomb stress in a regional scale with a significant impact to trigger the 2004 Kushiro Oki earthquake. The 2004 Kushiro Oki earthquake (Mw = 7.0) is another significant stressing event that changed the pattern of Coulomb stress in the area. We found that stressing events with magnitude smaller than 7.0 has minimal impact on Coulomb stress change in the Pacific slab. Similarly, comparatively deep focused large earthquakes could not change Coulomb stress significantly. Further the pattern of Coulomb stress change after the 2003 Tokachi Oki earthquake correlates the pattern of afterslip distribution in Hokkaido.  相似文献   

17.
The Dead Sea is a terminal lake whose level is currently dropping at a rate of about 1 m per year due to the over exploitation of all its tributaries. The lowering started about four decades ago but geological hazards appeared more and more frequently from the end of the 1980s. The water level lowering is matched by a parallel groundwater level drop, which results in an increasing intensity of underground and surface water flow. The diagonal interface between the Dead Sea brine and the fresh groundwater is pushed downwards and seawards. Nowadays, sinkholes, subsidence, landslides and reactivated salt-karsts affect wide coastal segments. Until now, mainly infrastructures were damaged and few people/animals were injured, but the ongoing development of tourism in this very attractive situation will increase the risk if precautionary measures are not included in the development plans. This paper discusses the main observations made all around the Dead Sea and shed a light on the differences between the geological hazards of the western shore (Israel, Palestinian Authority) and the eastern shore (Jordan). It is the first attempt to bring together an overview of the human-induced geological hazards encountered along the Dead Sea coast.  相似文献   

18.
The rupture process of the disastrous Sumatra–Andaman earthquake of 26 December 2004 was analyzed by array processes for teleseismic P-waves recorded by a dense broadband seismic array in Taiwan with epicentral distances of close to 31°. The azimuthal variation from the BATS array center to both ends of the rupture fault is approximately 21°, which is larger than that reported previously for seismic arrays used to image the rupture process of this earthquake, thereby providing a high spatial resolution in studying the source rupture behavior. Two array-processing methods were used to analyze teleseismic P-wave trains. Both analyses were based on data recorded by a broadband network, covering a region of 200 × 400 km, with the aim of evaluating the rupture behavior of the earthquake. Consistent results from both analyses indicate that the earthquake had a rupture duration exceeding 500 s, with major asperities encountered at 80, 260, and 330 s after the initiation of rupturing. We traced the ruptured fault for more than 1200 km from the point of initial rupture. The average rupture velocity was approximately 3.0 km/s and the major northward rupture propagation began at 80 s after the initiation of rupturing.  相似文献   

19.
A comprehensive record of lake level changes in the Dead Sea has been reconstructed using multiple, well dated sediment cores recovered from the Dead Sea shore. Interpreting the lake level changes as monitors of precipitation in the Dead Sea drainage area and the regional eastern Mediterranean palaeoclimate, we document the presence of two major wet phases ( 10–8.6 and  5.6–3.5 cal kyr BP) and multiple abrupt arid events during the Holocene. The arid events in the Holocene Dead Sea appear to coincide with major breaks in the Near East cultural evolution (at  8.6, 8.2, 4.2, 3.5 cal kyr BP). Wetter periods are marked by the enlargement of smaller settlements and growth of farming communities in desert regions, suggesting a parallelism between climate and Near East cultural development.  相似文献   

20.
The Vienna Basin Transfer Fault (VBTF) is a slow active fault with moderate seismicity (I max~8–9, M max~5.7) passing through the most vulnerable regions of Austria and Slovakia. We use different data to constrain the seismic potential of the VBTF including slip values computed from the seismic energy release during the 20th century, geological data on fault segmentation and a depth-extrapolated 3-D model of a generalized fault surface, which is used to define potential rupture zones. The seismic slip of the VBTF as a whole is in the range of 0.22–0.31 mm/year for a seismogenic fault thickness of 8 km. Seismic slip rates for individual segments vary from 0.00 to 0.77 mm/year. Comparing these data to geologically and GPS-derived slip velocities (>1 mm/year) proofs that the fault yields a significant seismic slip deficit. Segments of the fault with high seismic slip contrast from segments with no slip representing locked segments. Fault surfaces of segments within the seismogenic zone (4–14 km depth) vary from 55 to 400 km2. Empirical scaling relations show that these segments are sufficiently large to explain both, earthquakes observed in the last centuries, and the 4th century Carnuntum earthquake, for which archeo-seismological data suggest a magnitude of M ≥ 6. Based on the combination of all data (incomplete earthquake catalog, seismic slip deficits, locked segments, potential rupture areas, indications of strong pre-catalog earthquakes) we argue, that the maximum credible earthquake for the VBTF is in the range M max = 6.0–6.8, significantly larger than the magnitude of the strongest recorded events (M = 5.7).  相似文献   

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