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| Titel |
Slip-deficit on the Levant fault estimated by paleoseismological investigations |
| VerfasserIn |
Marthe Lefevre, Yann Klinger, Mahmoud Al-Qaryouti, Maryline Le Béon, Khaled Moumani, Marion Thomas, Stéphane Baize |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129796
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| Publikation (Nr.) |
 EGU/EGU2016-9956.pdf |
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| Zusammenfassung |
| The Levant fault is a major tectonic structure located east of the Mediterranean Sea. It is a
1200 km-long left-lateral strike-slip fault, which accommodates the northward movement of
the Arabic plate relatively to the Sinai micro-plate, with a ∼ 5mm/year slip-rate. This
slip-rate has been estimated over a large range of time scales, from a few years (gps) to
several hundred thousands of years (geomorphology). The geometry of the southern part of
the Levant fault, the Wadi Araba fault, is linear with only a few bends and steps. The
Middle-East is a region where there is an important and complete historical record of past
earthquakes. Nevertheless, due to the arid and unpopulated nature of the Wadi Araba, to
constrain location and lateral extent of those past earthquake with accuracy remains
challenging.
We excavated a trench ∼ 100 km north of Aqaba in the wadi Musa alluvial fan, next to
the largest compressional jog of the Wadi Araba. The stratigraphy contains three main units.
Two units are coarse and channelized, and sandy flat layers form the third unit. In the trench
the deformation is distributed over 15m, and is more pronounced in the eastern part. We can
identify at least 12 earthquakes, based on upward terminations of ground ruptures. 14C dating
of 28 charcoals distributed over the three documented trench walls, shows a 7000
year-long record and it allows us to match some events with historical earthquakes
in AD1458, AD1293, AD748, AD114, BC31. For other dated events, matching
with historical events remains more speculative considering the limited testimonies in
old ages. As the last earthquake in the Wadi Araba occurred in AD1458, with an
average slip rate of 5 mm/yr, about 2.7 m of slip-deficit have already accumulated,
suggesting that this area might be ripe for a large earthquake. Some of the events
recognized in our trench are attested north of the Dead Sea as well, such as the
AD749 earthquake, suggesting that long sections of the Levant Fault might also
rupture together, or in a short period, during earthquake series. Combining our
results with previous paleaoseismological studies in the region, we estimated lateral
extent of earthquakes and we built regional rupture scenarios. The lateral extent of
earthquake ruptures was also used to estimate the average co-seismic slip, using
classical scaling laws, thus to assess the cumulated slip related to each rupture
scenarios.
Eventually, we tried to balance long-term tectonic loading with the computed cumulated
slip to estimate the accumulated slip deficit for the Levant fault, from Aqaba to the south of
Lebanon, over the documented period. The seismic-moment budget shows that levels of slip
deficit, both north and south of the Dead Sea basin, are similarly high, which could
suggest that a seismic crisis could happen over the entire region in a near future. |
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