GPS Measurements of Crustal Deformation in Lebanon: Implication for Current Kinematics of the Sinaï Plate.
Abstract
The Levant fault is a major strike-slip fault bounding the Arabia and the Sinaï plates. Its kinematics, although understood in its main characteristics, remains partly unresolved in its quantification, especially in the Lebanese restraining bend. We present a GPS velocity field based on survey GPS data acquired in Lebanon (1999, 2002, 2010) and on continuous GPS data publicly available in the Levant area. To complete the measurements along the Levant fault, we combine our velocity field with previously published velocity fields. First, from our velocity field, we derive two velocity profiles, across the Lebanese fault system, which we analyze in terms of elastic strain accumulation. Despite the uncertainty on the locking depth of the main strand of the Levant fault, small lateral fault slip rates (2-4mm/yr) are detected on each profile, with a slight slip rate decrease (<1mm/yr) from south to north. The latter is consistent with published results south and north of Lebanon. Small compression (<0.5mm/yr), with most part of it located across Mount Lebanon, is also suggested. Second, we analyze the combined GPS velocity field in the Sinaï tectonic framework. We evaluate how well the Sinaï plate motion is described with an Euler pole. Due to heterogeneous velocity errors (5 times smaller for cGPS velocities wrt sGPS velocities), a unique pole estimation using all the data provides good statistical results. However, the residuals show systematic deviations at central and northern sGPS stations. Using only the velocities at these stations, the estimated pole is significantly different from the unique pole at 95% confidence level. This analysis highlights the difficulty to robustly resolve the rigid Sinaï plate motion while the uncertainties on the velocities are heterogeneous. New sGPS measurements on existing sites should improve the solution and help to conclude.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.G32A..05V
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITYDE: 1525 Paleomagnetism applied to tectonics: regional;
- global;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8158 Plate motions: present and recent;
- TECTONOPHYSICS