HR: 0800h
AN: T41F-1294    [Abstracts]
TI: Sources of the AD 551, 1202 and 1759 earthquakes (Lebanon and Syria)
AU: * Da‰ron, M
EM: daeron@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris - Laboratoire de Tectonique, 4 place Jussieu, Paris, 75252 France
AU: Elias, A
EM: elias@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris - Laboratoire de Tectonique, 4 place Jussieu, Paris, 75252 France
AU: Elias, A
EM: elias@ipgp.jussieu.fr
AF: Lebanese National Centre for Geophysics, Bhannes , B.P. 16-5432, Beirut, 1100-2040 Lebanon
AU: Klinger, Y
EM: klinger@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris - Laboratoire de Tectonique, 4 place Jussieu, Paris, 75252 France
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris - Laboratoire de Tectonique, 4 place Jussieu, Paris, 75252 France
AU: Jacques, E
EM: Eric.Jacques@eost.u-strasbg.fr
AF: Institut de Physique du Globe de Strasbourg, 5 rue Descartes, Strasbourg, 67084 France
AU: Sursock, A
EM: asursock@cnrs.edu.lb
AF: Lebanese National Centre for Geophysics, Bhannes , B.P. 16-5432, Beirut, 1100-2040 Lebanon
AB: The sources of three large (M$\sim$7.5) Near East earthquakes - in July, AD 551, May 1202 and Nov. 1759 - remain controversial, because their mesoseismal areas overlap, straddling the three sub-parallel active faults of the Lebanese restraining bend. Paleoseismic trenching in the Yammo\^{u}neh basin yields unambiguous evidence both for slip on the Yammo\^{u}neh fault in the 12th-13th centuries AD, and for the lack of a posterior event. Only two seismic events are visible on both walls, in the uppermost 80 cm of the trench. Based on the calibrated ages of 14C samples, the latest ground-breaking earthquake occurred between AD 1008 and 1345. The only possible candidate for this event is the 1202 earthquake, since macroseismic damage for other large Near East events was clearly located either well south (AD 1033) or well north (AD 1157 and 1170) of the Beqaa. The penultimate event in the trench has a 14C-calibrated date between AD 324 - 537 and AD 802 - 1001. Such dates cannot be used to rule out that the AD 551 event took place on the Yammo\^{u}neh fault. However, the 551 event is famous for having ruined most of the seaports on the Lebanese coast and having caused a large tsunami which wiped out Beirut. The recent discovery (SHALIMAR cruise, 2003) of fresh seismic scarps related to oblique thrusting on the seafloor offshore Beirut makes it more likely that rupture of one segment of the Mount Lebanon thrust system caused the AD 551 earthquake and tsunami. Thus, we propose that each of the three earthquakes discussed originated on a distinct fault: AD 551 on the Mount Lebanon thrust, 1202 on the Yammo\^{u}neh fault, and 1759 on the R\^{a}cha\"{i}ya-Serghaya fault. Our conclusion regarding the last two events is further supported by a comparison of the freshest visible seismic scarps, which indicates more recent slip on the R\^{a}cha\"{i}ya-Serghaya system than on the Yammo\^{u}neh fault. Regarding the latter, the trenching results suggest that a recurring 1202-like, M$\sim$7.5 event might be due this century, as part of a sequence similar to that of AD 1033 - 1202, whose beginning might already have been heralded by the 1995, Mw$\sim$7.3 Aqaba earthquake. Clearly, a thorough re-assessment of seismic hazard in Lebanon, and on the entire Levant fault, is overdue.
DE: 7221 Paleoseismology
DE: 7230 Seismicity and seismotectonics
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting