The association of micro-earthquake clusters with mapped faults in the Dead Sea basin

Abstract

About 1100 micro-earthquakes that occurred along the Dead Sea basin during the past 25 years express ongoing seismic activity along mostly obscured fault segments. We apply seismological and statistical methods in order to associate seismic activity with geological and geophysical data and to locate and characterize active fault segments in the basin; three regional 1-D velocity models and the double-difference method were used for the relocation of seismic events. Geostatistical analysis shows that in first order the micro-earthquakes reflect faulting along segments of the main longitudinal fault while seismic quiescence along historically active zones indicates locked segments and stress concentration. Based on waveform similarity, spatial and temporal proximity, we defi ne earthquake clusters that comprise about 30% of the relocated seismicity and two thirds of the total seismic moment. About 80% of the clusters are associated with N-S trending faults. In two cases the clusters indicate a migration of the seismicity in time and space, one of which preceded the largest earthquake in our catalog (M5.2). In addition to the associated longitudinal activity, several clusters appear to represent faulting in east-west orientation which is interpreted here as a secondary fault system.