Earthquake source characterization, moment tensor solutions, and stress field of small-moderate earthquakes occurred in the northern Red Sea Triple Junction

Abstract

We estimated moment tensor and centroid depth of eight small/moderate local earthquakes occurred between 2011 and 2013 in the northern Red Sea Triple Junction using a moment tensor inversion of near-source waveform data recorded by very broadband stations of the Egyptian National Seismic Network (ENSN). We also estimated the focal mechanism using the P-wave polarity data set and then compared it with the moment tensor inversion results. The moment tensor solutions are consistent with the focal mechanism obtained from the P-wave polarity data. We also estimated the stress field in the study area using the Multiple Inverse Method (MIM). Our results indicate that the axis of the minimum principal stress is a nearly horizontal NE-SW direction, while the axis of the maximum principal stress is nearly vertical. The direction of the minimum principal stress is consistent with the opening direction of the northern Red Sea zone, where the southern part of Gulf of Suez is currently under an extensional stress field with a NE-SW trending horizontal extension. These results are compatible with the kinematics of the Red Sea-Gulf of Suez rift.