HR: 1340h
AN: T43A-1095    [Abstracts]
TI: Episodic behavior of the Dead Sea fault from slip rate variations and integrated seismicity
AU: * Ferry, M
EM: matthieu.ferry@eost.u-strasbg.fr
AF: Institut de Physique du Globe, UMR 7516, 5, rue R. Descartes, Strasbourg, 67084, France
AU: Meghraoui, M
EM: mustapha@eost.u-strasbg.fr
AF: Institut de Physique du Globe, UMR 7516, 5, rue R. Descartes, Strasbourg, 67084, France
AU: Abou Karaki, N
EM: naja@ju.edu.jo
AF: Department of Environmental and Applied Geology, University of Jordan, Amman, 11942, Jordan
AU: Al-Taj, M
EM: masdouq1@hotmail.com
AF: Department of Earth and Environmental Sciences, The Hachemite University, Zarqa, 13115, Jordan
AU: Amoush, H
EM: geo_hani@yahoo.com
AF: Department of Environmental and Applied Geology, University of Jordan, Amman, 11942, Jordan
AB: The 110-km-long fault rupture of the Jordan Valley section of the Dead Sea Fault exhibits a significant late Quaternary active deformation and is capable of producing large and destructive earthquakes (Mw > 7.2). Here, we address its behavior over the last 48 kyr by means of historical seismicity, archeoseismicity, paleoseismicity and geomorphology to evidence variations in seismic activity and suggest a generally episodic behavior. First, we analyze 20 offset drainages evenly distributed along the southern section of the JVF. From the history of past lake-level fluctuations and intense rainfall episodes, we identify six climatic events likely to have triggered the onset of gully incisions in the Lisan and Damya formations and propose a well-constrained chronology using related absolute dating. Hence, measured lateral offsets from aerial photographs and field control points provide: i) a long-term average value of 4.9 mm/yr in good agreement with GPS velocities and ii) strong variations over short time spans with a threefold increase from 3.5 mm/yr to 11 mm/yr during a 2000-yr-long period. In addition, an integrated seismicity catalogue is produced from existing historical data, archeological results and original paleoseismic investigations at two trench sites. Archeological results from 10 sites, half of which located in the close vicinity of the fault, provide evidence for 7 destructive events since ~ 2900 B.C.. At Ghor Kabed, paleoseismic trenches dug across the bounding faults of a pull-apart basin show that at least two fault movements have occurred between A.D. 560 and A.D. 1800 (2sigma-calibration) and can be related with the A.D. 749 and A.D. 1033 large earthquakes (M>7) that struck the Jordan Valley. Further north, at Tell Es-Saydiyeh, paleoseismic trenches evidence up to 8 surface-rupturing events during the last 14 ka, of which the most recent may be correlated to the historical A.D. 1033 earthquake. The integrated catalogue reveals an episodic fault behavior with clusters of seismicity and quiescence periods as well as a 600- to 1000-yr-long recurrence interval for large earthquakes in the last 14 ka. Considering the last large earthquake in the Jordan Valley occurred in A.D. 1033, the fault may have accumulated 3.5 m to 5 m of slip. This pleads for a Mw 7.2+ earthquake yet to be released along the Jordan Valley fault segment.
DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 7221 Paleoseismology (8036)
DE: 8111 Continental tectonics: strike-slip and transform
SC: Tectonophysics [T]
MN: 2007 Fall Meeting