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<p>The left-lateral Dead Sea Fault (DSF) system is the main structural feature along which Africa and Arabia slide past one another in the eastern Mediterranean. Extending for about 170&#xa0;km north of the Dead Sea, the Lebanese Restraining Bend (LRB) encompasses the NNE-runing Mount Lebanon and the NE Anti-Lebanon ranges which are detached by the Valley of the Bekaa. Pre-instrumental earthquakes with fatalities are recorded along these active segments of the DSF system. In this study, we use a seismic tomography technique to invert a large number of P- and S-wave arrival times collected from the ISC seismological bulletins to demonstrate the crustal heterogeneity and map 3-D seismic velocity distributions along the central segment of the DSF system. Using the obtained P- and S-wave velocity (Vp, and Vs) models, we further compute Vp/Vs models for a better understanding of the crustal structures. The 3-D seismic velocity and Vp/Vs models exhibit strong lateral heterogeneities. Slower crustal and upper mantle velocities are revealed along the fault segments of the LRB and to the west along the easterly-dipping Mount-Lebanon thrust (MLT) fault system. Average to high Vp/Vs anomalies are revealed at crustal depths, especially close to the hypocentral zones of large crustal earthquakes which are generally located at the edge portions of the low-velocity anomalies. The ray path coverage of the present data set and the results of the resolution test imply that the imaged seismic anomalies are reliable features down to the uppermost mantle layers. Moreover, the present results are, in general, compatible with several geological and geophysical studies beneath the eastern Mediterranean such as passive <i>Sn</i> propagation, strong attenuation, slower than average velocities, emplacement of ophiolite suites, as well as Cenozoic volcanics.</p>

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Heterogeneous crustal structures along the central dead sea fault system: evidence from seismic tomography

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Mohamed K. Salah

摘要

The left-lateral Dead Sea Fault (DSF) system is the main structural feature along which Africa and Arabia slide past one another in the eastern Mediterranean. Extending for about 170 km north of the Dead Sea, the Lebanese Restraining Bend (LRB) encompasses the NNE-runing Mount Lebanon and the NE Anti-Lebanon ranges which are detached by the Valley of the Bekaa. Pre-instrumental earthquakes with fatalities are recorded along these active segments of the DSF system. In this study, we use a seismic tomography technique to invert a large number of P- and S-wave arrival times collected from the ISC seismological bulletins to demonstrate the crustal heterogeneity and map 3-D seismic velocity distributions along the central segment of the DSF system. Using the obtained P- and S-wave velocity (Vp, and Vs) models, we further compute Vp/Vs models for a better understanding of the crustal structures. The 3-D seismic velocity and Vp/Vs models exhibit strong lateral heterogeneities. Slower crustal and upper mantle velocities are revealed along the fault segments of the LRB and to the west along the easterly-dipping Mount-Lebanon thrust (MLT) fault system. Average to high Vp/Vs anomalies are revealed at crustal depths, especially close to the hypocentral zones of large crustal earthquakes which are generally located at the edge portions of the low-velocity anomalies. The ray path coverage of the present data set and the results of the resolution test imply that the imaged seismic anomalies are reliable features down to the uppermost mantle layers. Moreover, the present results are, in general, compatible with several geological and geophysical studies beneath the eastern Mediterranean such as passive Sn propagation, strong attenuation, slower than average velocities, emplacement of ophiolite suites, as well as Cenozoic volcanics.