Tectonics of the Dead Sea Fault Driving the July 2018 Seismic Swarm in the Sea of Galilee (Lake Kinneret), Israel

Abstract

Northern Israel was struck during July 2018 by a ML4.4 earthquake followed by a seismic sequence that lasted about 30 days. This seismic sequence occurred in the center of a temporary seismic network deployed around the Sea of Galilee (Lake Kinneret). The network was installed to investigate the regional kinematics of the Dead Sea Fault, which is a major transform fault running N-S for more than 1,000 km. The data allowed us to develop a local velocity model for the Sea of Galilee. We relocated more than 600 earthquakes and calculated 27 focal mechanisms pointing out a complex kinematic setting, possibly controlled by fluids at depth. The seismic sequence developed along a NNW-striking direction and it is bounded to the east by the N-striking Dead Sea fault. Hypocenter depths range between 6 and 13 km. Directions of the principal stress tensors suggest a transtentional deformation, in agreement with the overall kinematics of the region. We analyze and discuss our data set to investigate mechanisms that potentially triggered the observed seismic swarm, including exacerbated ground water pumping proposed by previous authors. We suggest that the seismic sequence is driven by the dissipation of the elastic load that accumulated in this region.