Fracturing patterns, stress fields and earthquakes in the Southern Dead Sea rift

Integrated investigations including the structural analysis of shear fractures and fault zones, the reconstruction of stress fields and the fractal analysis of the epicentral field of recent earthquakes have been pursued in the Dead Sea rift. The N-S and NW-SE trending faults are very extensive and they display large zones of crushed rock compared with faults of other orientations. According to the fractal analysis of the seismicity over the period of 1983-2002 and a review of historical destructive earthquakes associated with faulting of archaeological sites, large N-S and NW-SE fault zones traced in different sites are the major structures that control the seismic activity in the southern part of the rift. Many of the N-S trending faults are well pronounced within the basins but they are not as frequent in the inter-basin link zones. Meso-structural features document normal fault displacements along the major faults within basins. In the uplifted inter-basin links the kinematics varies from normal to strike-slip faulting along the same fault zones. The NW-SE faults are characterized by normal and oblique displacement, the E-W faults by strike-slip displacements and the NE-SW faults by composite strike-slip and normal displacement. The tectonic stress fields reconstructed from shear fractures orientations show that two main types of local stress tensors are associated with the structural development of the Dead Sea rift: (1) tension with E-W (mainly) and ENE-WSW trending σ3 and (2) transcurrent with NE-SW (sometimes nearly E-W) trending σ3 and NW-SE (sometimes nearly N-S) trending σ1. The comparison between the obtained data and analog models of structural systems formed under variable loading conditions indicates that the observed features and the inferred stress fields in the Dead Sea rift are typical to oblique extension settings.