HR: 09:15h
AN: T51C-06    [PDF]
TI: First Constraints On the Slip Rate of the Yammouneh Fault (Levant Fault System) Determined by Cosmogenic \textsuperscript{36}Cl Exposure Dating of Offset Alluvial Fans
AU: * Da\"eron, M
EM: daeron@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Bo\^ite 89 - 4 place Jussieu, Paris Cedex 05, 75252 France
AU: Benedetti, L
EM: benedetti@cerege.fr
AF: Centre Europ\'een de Recherche et d'Enseignement de G\'eosciences de l'Environnement, BP 80 - Europole de l'Arbois, Aix-en-Provence, 13545 France
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Bo\^ite 89 - 4 place Jussieu, Paris Cedex 05, 75252 France
AU: Sursock, A
EM: geophys@cnrs.edu.lb
AF: Conseil National de la Recherche Scientifique du Liban, BP 16-5432, Beirut, 0000 Lebanon
AU: Finkel, R
EM: rfinkel@llnl.gov
AF: Lawrence Livermore National Laboratory - CAMS, MS L-206, 7000 East Ave, Livermore, CA 94550-9234 United States
AB: The most active seismogenic structure along the eastern shore of the Mediterranean is the left-lateral strike-slip Levant fault, plate boundary between Arabia and Africa. To this day there is consensus neither on its present slip rate and segmentation, nor on the exact size and frequence of the earthquakes it generates. Between latitudes 33\textsuperscript{o} N and 35\textsuperscript{o} N in Lebanon, the Levant fault's trace veers eastwards by 24\textsuperscript{o}, forming a 160km-long restraining bend, responsible for the uplift of Mount Lebanon (3083m). Most of the resulting transpressive deformation is partitioned between two main structures: the offshore Tripoli-Beirut thrust and the Yammouneh strike-slip fault, whose degree of seismogenic activity has been questioned (various estimations of its modern slip rate range from 0 to 8mm/yr). Using aerial photographs, satellite images, topographic maps and field observations, we mapped and measured left-laterally offset alluvial fans and gullies along the Yammouneh fault. The measured offsets range from less than 10m to about 3km. To constrain the slip rate of the Yammouneh fault, limestone cobbles were sampled on three alluvial fans, each offset by 40--50m. The concentrations of \textsuperscript{36}Cl\ and stable Chlorine in the 48 samples were measured by accelerator mass spectrometry at the LLNL-CAMS. The first results suggest an average slip rate of 5--10mm/yr along the Yammouneh fault in the last 8,000 years.
DE: 7230 Seismicity and seismotectonics
DE: 8107 Continental neotectonics
DE: 8158 Plate motions--present and recent (3040)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting