The Dead Sea fault (DSF) plate boundary has accommodated relative sinistral motion between the Sinai and Arabian plates since the Neogene. Geologically based models point to a long-term (5-0 m.y.) ~N-trending relative motion roughly parallel to the central sector of the DSF. GPS based calculations of present-day relative motion between the Sinai and Arabian plates indicate a northward increasing convergent component across the DSF, suggesting a kinematic change over the Plio-Pleistocene period. We study the evolving deformation of the Hula rhomb-shaped graben situated along the central sector of the DSF in order to examine the possible kinematic change. The Hula graben is widely accepted as a pull-apart basin, part of a series of basins extending southward. We use a 3D approach, combining mapped surface structures with subsurface seismic reflection profiles (~173 km) and borehole data (38 boreholes), gathered here into a single GIS database. Results indicate that during the mid-Pleistocene a major tectonic transition modified the structure of the basin fill. A sub-vertical NNW-trending left-lateral through-going strike-slip fault developed diagonally across the basin. Consequently, the basin entered a new geodynamic phase where subsidence was controlled by both the basin bordering faults and the diagonal fault, while the vertical displacement across the transverse faults is minor.

 (a) Top HzB structural map (MSL datum) showing a gentle southward slope from 350 m (outcrops) to -534 m (north of the diagonal fault). Dashed contours mark extrapolations. Pre-HzB fault set #1 is marked in dark gray. Fault set #2 bounded the southward flow of the basalts. HzB outcrops are marked as an orange area and triangles, together with height above sea level. Capital letters denote block names. (b) Structural blocks comprising the Hula basin and surroundings after the development of the diagonal fault. See text for further explanations. (c) Dip-curvature, second derivative of the gravity field superposed by structural 0.5 km contours of the base of the Hula basin fill (after Rybakov et al., 2003). Location of selected seismic events and focal plane solutions of earthquakes recorded between 1982 and 1997 (after Ron et al., 1997) are marked. Note that the depocenter location is nearly stationary over time. EA - En Awwazim, Q8 - Qiryat Shemona city.