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Approximately 4 yr of campaign and continuous Global Positioning System (GPS) measurements across the Dead Sea fault system (DSFS) in Lebanon provide direct measurements of interseismic strain accumulation along a 200-km-long restraining bend in this continental transform fault. Late Cenozoic transpression within this restraining bend has maintained more than 3000 m of topography in the Mount Lebanon and Anti-Lebanon ranges. The GPS velocity field indicates 4-5 mm yr(-1) of relative plate motion is transferred through the restraining bend to the northern continuation of the DSFS in northwestern Syria. Near-field GPS velocities are generally parallel to the major, left-lateral strike-slip faults, suggesting that much of the expected convergence across the restraining bend is likely accommodated by different structures beyond the aperture of the GPS network (e.g. offshore Lebanon and, possibly, the Palmyride fold belt in SW Syria). Hence, these geodetic results suggest a partitioning of crustal deformation involving strike-slip displacements in the interior of the restraining bend, and crustal shortening in the outer part of the restraining bend. Within the uncertainties, the GPS-based rates of fault slip compare well with Holocene-averaged estimates of slip along the two principal strike-slip faults: the Yammouneh and Serghaya faults. Of these two faults, more slip occurs on the Yammouneh fault, which constitutes the primary plate boundary structure between the Arabia and Sinai plates. Hence, the Yammouneh fault is the structural linkage that transfers slip to the northern part of the transform in northwestern Syria. From the perspective of the regional earthquake hazard, the Yammouneh fault is presently locked and accumulating interseismic strain

Evidence of long-term, late Cenozoic uplift, as well as strike-slip faulting, is revealed by topographic and geological features along the northern 500 km of the Dead Sea fault system

Recent neotectonic, palaeoseismic and GPS results along the central Dead Sea fault system elucidate the spatial distribution of crustal deformation within a large (c.180-km-long) restraining bend along this major continental transform. Within the ‘Lebanese’ restraining bend, the Dead Sea fault system splays into several key branches, and we suggest herein that active deformation is partitioned between NNE–SSW strike-slip faults and WNW–ESE crustal shortening. When plate motion is resolved into strike-slip parallel to the two prominent NNE–SSW strike-slip faults (the Yammouneh and Serghaya faults) and orthogonal motion, their slip rates are sufficient to account for all expected strike-slip motion. Shortening of the Mount Lebanon Range is inferred from the geometry and kinematics of the Roum Fault, as well as preliminary quantification of coastal uplift. The results do not account for all expected crustal shortening, suggesting that some contraction is probably accommodated in the Anti-Lebanon Range. It also seems unlikely that the present kinematic configuration characterizes the entire Cenozoic history of the restraining bend. Present-day strain partitioning contrasts with published observations on finite deformation in Lebanon, demonstrating distributed shear and vertical-axis block rotations. Furthermore, the present-day proportions of strike-slip displacement and crustal shortening are inconsistent with the total strike-slip offset and the lack of a significantly thickened crust. This suggests that the present rate of crustal shortening has not persisted for the longer life of the transform. Hence, we suggest that the Lebanese restraining bend evolved in a polyphase manner, involving an earlier episode of wrench-faulting and block rotation, followed by a later period of strain partitioning.

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