Focal mechanism of earthquakes from the June 1987 swarm in Aswan, Egypt, calculated by the moment tensor inversion

• Autorzy: Awad H. , Kwiatek G.
• Języki publikacji: EN

Abstrakty

EN

We obtained seismic moment tensor solutions of ten events from the June 1987 earthquake swarm, which occurred along the Kalabsha fault zone in the northern part of the Lake Aswan area in Egypt. In addition, the composite fault plane solution of this sequence was also calculated. The waveform data were obtained from the Aswan seismological network, which consists of 13 field stations with short period seismometers GS-13. The June 1987 swarm was a sequence of microearthquakes (M ? 3.4), shallow (0-10 km) events forming two successive bursts, which took place on June 17 and 19. The moment tensor solutions indicate that the focal mechanisms of events from this swarm sequence are expressed by right-lateral strike slip faults. They represent also an effective east-west compressional stress field acting in the area. Geological and geophysical data demonstrate that the Kalabsha fault zone is a right-lateral strike slip fault that consists of several fault segments trending in the east-west direction, perpendicular to the axis of the main course of the Lake As-wan. Thus, the focal mechanisms of the 1987 events are consistent with the local tectonics of the area.

Słowa kluczowe

EN

earthquake swarm; focal mechanism; moment tensor inversion; spectral ray-tracer; Lake Aswan

• Wydawca: Instytut Geofizyki PAN
• Czasopismo: Acta Geophysica Polonica
• Rocznik: 2005
• Tom: Vol. 53, nr 3
• Strony: 275--291
• Opis fizyczny: Bibliogr. 30 poz.

Twórcy

autor

Awad H.

• National Research Institute of Astronomy and Geophysics, 11421-Helwan, Cairo, Egypt

autor

Kwiatek G.

• Institute of Geophysics, Polish Academy of Science ul. Księcia Janusza 64, 01-452 Warszawa, Poland

Bibliografia

• Awad, H., 1994, Investigation of the tectonic setting, seismic activity and crustal deformation in Aswan seismic region, Egypt, Ph.D. Thesis, Tokyo University (unpublished).
• Awad, H., 2002, Seismicity and water level variations in the Lake Aswan area in Egypt 1982 -1997, J. Seism. 6, 459-467.
• Awad, H., and M. Mizoue, 1995a, Earthquake activity in the Aswan region, Egypt, Pageoph 145, 1, 69-86.
• Awad, H., and M. Mizoue, 1995b, Tomographic inversion for the three-dimensional structure of the Aswan region, Egypt, Pageoph 145, 1, 193-207.
• Awad, H., P. Denton, P. Maguire and G. Hassib, 2003, Relocation of swarm events in the June 1987 earthquake sequence from the Lake Aswan area in Egypt, Pageoph 160, 1245 -1257.
• Claerbout, E.W., and F. Muir, 1973, Robust modeling with erratic data. Geophysics 38, 826 -844.
• Dębski, W., 2002, Seismic tomography software package. Pubis. Inst. Geophys. Pol. Acad. Sc. B-30, 103 pp.
• Dębski, W., and M. Ando, 2004, Spectral ray tracer: A class of accurate two-point ray tracers, Acta Geophys. Pol. 52, 1-13.
• El-Shazly, E.M., 1977, The geology of the Egyptian region. The Ocean Basin and Margins 145, 193-207.
• Fitch, T.J.. W.D. McCovan and M.W. Shields, 1980, Estimation of the seismic moment tensor from teleseismic body wave data with applications to intraplate and mantle earthquakes, J. Geophys. Res. 85, 3817-3828.
• Hanks, Т.е.. and H. Kanamori, 1979, A moment magnitude scale, J. Geophys. Res. 84, 2348 -2350.
• Haskell, N.A., 1953, The dispersion of surface waves in multilayered media. Bull. Seism. Soc. Am. 43, 17-34.
• Hassib, G.H., 1990, A study on the earthquake mechanics around the High Dam Lake, Aswan, Egypt, Ph.D. Thesis, Faculty of Science, South Valley Univ., Sohag, Egypt (unpublished).
• Ingber, L., 1989, Very fast simulated re-annealing: A comparison, Oper. Res. Manage. Sci. 33, 523.
• Ingber, L., 1993, Simulated annealing: Practice versus theory. Mathematical Computer Modelling 18, 29-57.
• Issawi, B., 1978, Geology of Nubia west area, western desert, Ann. Geol. Survey Egypt.
• Issawi, B., 1982, Geology of the southwestern desert of Egypt, Ann. Geol. Survey Egypt.
• Kebeasy, R.M., M. Maamon and E.M. Ibrahim, 1981, Aswan Lake induced earthquakes. Bull. Intern. Inst. Seism. Earthq. Engin. 19, 155-160.
• Kebeasy, R.M., A.I. Bayoumi and A.A. Gharib, 1992, Crustal structure modeling for the northern part of the Aswan Lake area using seismic waves generated by explosions and local earthquakes, J. Geodyn. 14, 1-24.
• Malone, S., and S. Wiemer, 2001, A software package to analyze seismicity: ZMAP, Seism. Res. Lett. 72, 374-383.
• Mekkawi, M., 2003, Magnetotelluric and seismicity studies along active fault zones, Ph.D. Thesis, Faculty of Science, University of Neuchatels, Switzerland (unpublished).
• Mekkawi, M., A. Hassoup, J.-R. Grasso and P.-A. Schnegg, 2002, Fractal and spectral analysis of the earthquake sequences along Aswan Lake, Egypt, EGS Nice, April, SE085.
• Mekkawi, M., J.-R. Grasso and P.-A. Schnegg, 2004, A long-lasting relaxation of seismicity at Aswan, Egypt, 1982-2001, Bull. Seism. Soc. Am. 94,479-492.
• Mogi, K., 1967, Earthquakes and fractures, Tectonophysics 5, 35-55.
• Simpson, D.W., A.A. Gharib and R.M. Kebeasy, 1990, Induced seismicity and changes in water level at Aswan reservoir, Egypt, Gerlans. Beitr. Geophysik Leipzig 99, 191-204.
• Suetsugu, D., 1998, Practice on source mechanism, USEE Lecture Notes, 104 pp.
• Velis, D.R., and T.J. Ulrych, 2001, Simulated annealing ray tracing in complex three-dimensional media, Geophys. J. Int. 145, 447-459.
• Wiejacz, P., 1991, Investigation of focal mechanisms of mine tremors by the moment tensor inversion, Ph.D. Thesis, Inst. Geophys. Pol. Acad. Sci., Warszawa (in Polish, unpublished).
• Wiemer, S., and J. Benoit, 1996, Mapping the b-value anomaly at 100 km depth in the Alaska and New Zealand subduction zones, Geophys. Res. Lett. 23, 1557-1560.
• Wiemer, S., S. McNutt and M. Wyss, 1998, Temporal and three dimensional spatial analysis of the frequency-magnitude distribution near Long Valley Caldera, California, J. Geophys. Int. 134, 409-421.