12,000-Year-Long Record of 10 to 13 Paleoearthquakes on the Yammoûneh Fault, Levant Fault System, Lebanon
Abstract
We present results of the first paleoseismic study of the Yammoûneh fault, the main on-land segment of the Levant fault system within the Lebanese restraining bend. A trench was excavated in the Yammoûneh paleolake, where the fault cuts through finely laminated sequences of marls and clays. First-order variations throughout this outstanding stratigraphic record appear to reflect climate change at centennial and millennial scales. The lake beds are offset and deformed in a 2-m- wide zone coinciding with the mapped fault trace. Ten to thirteen events are identified, extending back more than ~12 kyr. Reliable age bounds on seven of these events constrain the mean seismic return time to 1127 ± 135 yr between ~12 ka and ~6.4 ka, implying that this fault slips in infrequent but large (M ~ 7.5) earthquakes. Our results also provide conclusive evidence that the latest event at this site was the great A.D. 1202 historical earthquake, and suggest that the Yammoûneh fault might have been the source of a less well-known event circa A.D. 350. These findings, combined with previous paleoseismic data from the Zebadani valley, imply that the parallel faults bounding the Beqaa release strain in events with comparable recurrence intervals but significantly different magnitudes. Our results contribute to document the clustering of large events on the Levant fault into centennial episodes, such as that during the eleventh through twelfth centuries, separated by millennial periods of quiescence, and raise the possibility of a M > 7 event occurring on the Yammoûneh fault in the coming century. Such a scenario should be taken into account in regional seismic-hazard assessments and planned for accordingly.
Additional Information
© 2007 Seismological Society of America. Manuscript received 15 May 2006. Many thanks to everyone at the National Center for Geophysical Research in Bhannes, Lebanon, for their invaluable help in the field. This work has been supported by the National Council for Scientific Research of Lebanon, the Institut National des Sciences de l'Univers of France, and the French Ministe`re des Affaires Etrange`res. Additional funding was provided by the Institut de Physique du Globe de Paris. We wish to thank NCSR General Secretary M. Hamze, for his long-term support; G. Seitz and M. Kashgarian, for help and advice about radiocarbon sample processing and AMS; and F. Gasse, for sharing her early paleoclimatic and palynological results. This article benefitted greatly from thorough reviews by T. Niemi and G. Biasi. This is Institut de Physique du Globe de Paris contribution no. 2190.Attached Files
Published - DAEbssa07.pdf
Supplemental Material - plate_1.pdf
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Additional details
- Eprint ID
- 17709
- Resolver ID
- CaltechAUTHORS:20100309-142208165
- National Council for Scientific Research of Lebanon
- Institut National des Sciences de l'Univers of France
- French Ministe`re des Affaires Etrange`res
- Institut de Physique du Globe de Paris
- Created
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2010-03-11Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field