Dynamic Source Parameters of Significant Earthquakes in the Gulf of Aqaba, Egypt

Abstract

Several seismological and paloseismolgical studies and historical reports have indicated that Gulf of Aqaba is characterized by higher seismicity than any other seismogenic sources around Egypt. Accordingly, surrounding areas have been impacted by several destructive earthquakes (AD 1068, AD 1212, AD 1229, AD 1458, and AD 1995). Cities situated around the Gulf of Aqaba have experienced different damage levels due to historical and instrumental earthquakes resulting in considerable fatalities. The Aqaba earthquake which occurred on November 22, 1995 (Moment magnitude (Mw) = 7.3) was the largest recorded earthquake along with the Dead Sea Fault System, strongly felt at Eastern Mediterranean region. Many seismic sequences have ocuuerd in the Gulf of Aqaba in the last decades and some of them continued for almost two years. This paper applies a spectral decomposition method based on a reference site to correct the source spectra from the path and site effects by employing Iterative Least Square analysis. The obtained displacement source spectra are modulated with Brune’s omega square type spectrum. The dynamic earthquakes parameters are computed using the S-wave window for the significant Gulf of Aqaba earthquakes. 50 earthquakes have been used in this study with Ml 3.0 to 6. The calculated seismic moments range spans from 1.48E+19 to 2.193E+22 dyne-cm, and the corner frequency range spans from 4.1 to 8.5 Hz. The source radii span which range from 84.3 m to 173.4 meters. The observed stress drops vary from 0.3 to 371.7 megapascal (Mpa).