Paleoseismic evidence for time dependency of seismic response on a fault system in the southern Arava Valley, Dead Sea rift, Israel.
Rivka Rivka Amit, et al. Geological Survey of Israel, 30 Malkhe Israel Street, Jerusalem 95501, Israel. Pages 192-206.
The Elat fault system in the southern Arava Valley the Dead Sea Rift, Israel, is a complex fault zone, characterized by marginal normal faults and central sinistral strike-slip faults. Paleoseismic evidence shows that it has generated at least fifteen earthquakes of magnitudes (M) larger than 6 during the Late Pleistocene and the Holocene (80 ka). The late Pleistocene is characterized by earthquakes that displace the surface by 1-1.5 m, with magnitudes between M6.7 to M7 and an average recurrence interval of 2.80.7 ka. The Holocene is characterized by a higher frequency of tectonic events with a recurrence interval of 1.20.3 ka, but lower displacement amounts (0.2-1.3 m) and lower earthquake magnitudes (M5.9 - M6.7). Historical records document the last seismic event in the Elat fault zone as of about 1000 years ago. The decrease in tectonic activity with time is inferred from the concentration of tectonism in the central part of the Elat fault zone and decreased seismicity in the eastern and western margins. The magnitude range determined for the central zone (M6.1 - M6.7) was likely not high enough to activate the marginal faults. The decrease in earthquake magnitudes with time, combined with the observations that the last large event occurred in 1068 A.D. and that no microseismicity has been detected during the last 15 years, might signal locking of the Elat fault zone. This may result from episodic global reorganization of the systems mode of strain energy release, reflected in the configurational entropy of stress states on the fault. These results hav
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8-Feb-2002