Stress field in the central and northern parts of the Gulf of Suez area, Egypt from earthquake fault plane solutions

Abstract

Earthquake focal mechanism solutions from 18 events in the central and northern parts of the Gulf of Suez with local magnitudes ranging from 2.8 to 5.2 and occurring between 1983 and 2004 are used to determine the type of motion and stress pattern of the region. Fault plane solutions show mostly normal component; pure normal faulting mechanisms and normal faulting with a strike-slip component. Only some mechanisms show pure strike-slip faulting. The fault planes strike in NW, WNW, NNE and ENE directions, in conformity with the geologically observed striking faults in the northern and central parts of the gulf. The principal stress orientation is also estimated by inverting the selected focal mechanism solutions. The results show that the northern part of the Gulf is subjected to NE–SW to NNE–SSW extension, with a horizontal σ 3 (plunge 3°) and subvertical σ 1 (plunge 80°). This means that the horizontal extensional stresses are still present in the central/northern Gulf of Suez.