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.
Bibliographical noteFunding Information:
This work was made possible through the financial support of the Earth Science Research Administration of the Ministry of National Infrastructures and the CFS foundation. The authors thank Gideon Rosenbaum, Orna Ben-Dov and Dina Stiber for the laboratory analyses, and Bat-Sheva Cohen and Nehama Shragai for drawing the figures. We thank Mrs. Ximena Barrientos and Mrs. Bevy Katz for editorial assistance. Grateful acknowledgement extended to B. Begin for his constructive comments. We especially thank the technicians of the Geological Survey of Israel whose encouragement and unlimited help under difficult field conditions contributed to the success of this study. Comments by E. Tondi and C. dePolo greatly improved the manuscript.
- Dead Sea Transform
- Earthquake magnitude
- Historical earthquakes
- Recurrence interval