Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/1225
AuthorsBadawy, A. 
TitleThe present-day stress field in Egypt
Issue DateJun-2001
Series/Report no.44/3
URIhttp://hdl.handle.net/2122/1225
Keywordsstress field
focal mechanisms
break-outs
stress regime
Subject Classification04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability 
05. General::05.02. Data dissemination::05.02.02. Seismological data 
AbstractThe present-day stress field has been investigated by the analysis of the directions of maximum horizontal stress (ó 1 ) inferred from earthquake focal mechanisms and borehole breakouts in Egypt. The results indicate that strike-slip and normal faulting movements characterize the majority of the earthquake focal mechanisms; only a few events are of reverse faulting type. The analysis of 35 mechanisms suggests that the present-day stress field in Southern Egypt is dominated by a strike-slip stress regime (SS) and it is mainly transtensional (NS: normal faulting with strike-slip component) in Northern Egypt. The orientation of P-axes reflects that the maximum horizontal stress (ó 1) in Southern Egypt is uniform and aligned to nearly E-W direction while in Northern Egypt it is aligned with an even mix of NW-SE and nearly E-W compression. Along the Gulf of Aqaba, the southern part of the Dead Sea Fault (DSF), the focal mechanism solutions indicate that the maximum horizontal stress is presently oriented NW-SE, corresponding to a strike-slip mechanism in concert with geological evidence. More detailed investigations have been performed for the Gulf of Suez. We compare our results to the near-surface stress measurements from borehole breakouts to see if there is a change in orientations with depth. Shallow stress directions derived from borehole breakouts are not consistent with the deep stress directions derived from earthquakes focal mechanisms. About 73% of 30 borehole breakouts measurements indicate NW-SE alignment of the maximum horizontal stress and 27% are ENE-WSW. The direction of ó 1 inferred from the focal mechanism solutions is changing from NE-SW to ENE-WSW. Therefore, at least in this area, the stress direction is not constant throughout the crust.
Appears in Collections:Annals of Geophysics

Files in This Item:
File Description SizeFormat 
05.pdf4.86 MBAdobe PDFView/Open
Show full item record

Page view(s)

63
checked on Apr 23, 2017

Download(s)

368
checked on Apr 23, 2017

Google ScholarTM

Check