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Seismic Anisotropy and Stress-Field Variations Along the Dead Sea Fault Zone in Northern Israel

Description: 

Geological observations based mainly on stress (strain)-indicating meso-scale markers suggest that the local maximum horizontal compressive stress (S_Hmax) direction along the Dead Sea Fault (DSF) system in northern Israel changes considerably over short distances from a ~N-S, fault-parallel orientation in the south to an ~E-W, fault-perpendicular orientation in the north. However, the association of the meso-scale markers to the present-day stress field is not well constrained as many of them could have formed at any stage during the DSF evolution. In this study, we use a large dataset of Shear-Wave Splitting (SWS) measurements, taken from local DSF-related earthquakes, to characterize the azimuthal seismic anisotropy of the upper-crust at this critical turning point of the DSF system, near the Lebanese Restraining Bend. The SWS directions commonly align parallel to the inferred local S_Hmax as revealed by the meso-scale markers, supporting their association with the current stress field. In several stations, SWS fast directions indicate azimuthal anisotropy at high angles to the trace of the master fault, indicating that stress-induced anisotropy represents a more plausible mechanism for SWS than structure-controlled anisotropy. The SWS measurements suggest that a northward counterclockwise rotation of the crustal S_Hmax is present along this segment of the DSF, supporting previous notation on the transition from divergent to convergent strike-slip faulting in this area.

Session: Anisotropy Across Scales - I

Type: Oral

Date: 5/3/2024

Presentation Time: 08:15 AM (local time)

Presenting Author: Guy

Student Presenter: Yes

Invited Presentation: 

Authors