Distributed earthquake focal mechanisms in the Aegean Sea


A. Kiratzi
C. Benetatos
Z. Roumelioti
Résumé

Nearly 2,000 earthquake focal mechanisms in the Aegean Sea and the surroundings for the period 1912- 2006, for 1.5 <M<7.5, and depths from 0 to 170 km, indicate a uniform distribution and smooth variation in orientation over wide regions, even for the very small magnitude earthquakes. ~ 60% of the focal mechanisms show normal faulting, that mainly strikes ~E-W. However, a zone ofN-S normal faulting runs the backbone of Albanides-Hellenides. Low-angle thrust and reverse faulting is confined in western Greece (Adria-Eurasia convergence) and along the Hellenic trench (Africa-Eurasia). In the central Aegean Sea the effect of the propagating tip of the North Anatolian Fault into the Aegean Sea is pronounced and strike-slip motions are widely distributed. Shearing does not cross central Greece. Strike-slip motions reappear in the Cephalonia-Lefkada Transform Fault zone and in western Péloponnèse, which shows very complex tectonics, with different types of faulting being oriented favourably and operating under the present stress-field. Moreover, in western Péloponnèse the sense of the observed shearing is not yet clear, whether it is dextral or sinistral, and this lack of data has significant implications for the orientation of the earthquake slip vectors compared to the GPS obtained velocity vectors.

Article Details
  • Rubrique
  • Geophysics and Seismology
Téléchargements
Les données relatives au téléchargement ne sont pas encore disponibles.
Références
Benetatos, C, Roumelioti, Z., Kiratzi, Α., and Melis, N., 2002. Source parameters of the M 6.5 Skyros island (North Aegean Sea) earthquake of July 26, 2001, Ann. Geophys., 45, 513-526.
Dewey, J.F., and Sengör, A.M.C., 1979. Aegean and surrounding regions: complex multiple and continuum tectonics in a convergent zone, Geol. Soc. Amer. Bull., 90, 84-92.
Dreger, D., and Helmberger, D., 1990. Broadband modelling of local earthquakes, Bull. Seismol. Soc. Am., SO, 1162-1179.
Dreger, D., and Helmberger, D., 1991. Complex faulting deduced from broadband modelling of the 28 February 1990 Upland earthquake (ML=5.2), Bull. Seismo!. Soc. Am., 81, 1129-1144.
Dreger, D., and Helmberger, D., 1993. Determination of source parameters at regional distances with single station or sparse network data, J. Geophys. Res., 98, 8107-8125. England, and McKenzie, 1982.
Ganas, Α., Drakatos, G., Pavlides, S., Stavrakakis, G., Ziazia, M., Sokos, E., and Karastathis, V., 2005. The 2001 Mw=6.4 Skyros earthquake, conjugate strike-slip faulting and spatial variation in stress within the central Aegean Sea, J. Geodyn., 39,61-77.
Jackson, J., 1994. Active tectonics of the Aegean region, Annu. Rev. Earth Planet. Sci., 22, 239-271.
Jackson, J., and McKenzie, D., 1988. Rates of active deformation in the Aegean Sea and surrounding regions, Basin Res., 1, 121-128.
Kiratzi, Α., 2002. Stress tensor inversions along the westernmost north and central Aegean Sea, Geophys. J. Int., 106, 433^90.
Kiratzi, Α., and Louvari, E., 2003. Focal mechanisms of shallow earthquakes in the Aegean Sea and the surrounding lands determined by waveform modelling: a new database, J. Geodyn., 36,251-274.
Koukouvelas, I., and Aydin, Α., 2002. Fault structure and related basins of the North Aegean Sea and its surroundings, Tectonics, 21 (5), 1046, doi:10.1029/2001TC901037.
Louvari, E., and Kiratzi, Α., 1997. Rake: a Window's program to plot earthquake focal mechanisms and stress orientation, Computers and Geosciences, 23, 851-857.
McCaffrey, R., and Nâbèlek, J., 1987. Earthquakes, gravity, and the origin of the Bali Basin: an example of nascent continental fold-and-thrust belt, J. Geophys. Res., 92,441-460.
McClusky, S., Balassanian, S., Barka, Α., Demir, C, Georgiev, I., Hamburg, M., Hurst, K., Kahle, Η., Kastens, Κ., Kekelidze, G., King, R., Kotzev, V., Lenk, Ο., Mahmoud, S., Mishin, Α., Nadariya, M., Ouzounis, Α., Paradissis, D., Peter, Y., Prilepin, M., Reilinger, R., Sanli, I., Seeger, H., Tealeb, Α., Toksoz, M.N., and Veis, G., 2000. Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus, J. Geophys. Res., 105, 5695-5720.
McKenzie, D., 1972. Active tectonics of the Mediterranean region, Geophys. J. R. astr. Soc, 30, 109-185.
McKenzie, D., 1978. Active tectonics of the Alpine-Himalayan belt: the Aegean Sea and surrounding regions, Geophys. J. R. astr. Soc, 55, 217-254.
Nyst, M., and Thatcher, W., 2004. New constraints on the active tectonic deformation of the Aegean,/. Geophys. Res., 109, doi:l0.1029/2003JB002830.
Papazachos, B.C., Kiratzi, A.A., and Karacostas, B.G., 1997. Toward a homogeneous momentmagnitude determination for earthquakes in Greece and the surrounding area, Bui. Seism. Soc. Am., 87,474-483.
Papazachos, B.C., Papadimitriou, E.E., Kiratzi, A.A., Papazachos, C.B., and Louvari, E., 1998. Fault plane solutions in the Aegean Sea and the surrounding area and their tectonic implication, Boll. Geof. Teor. App., 39, 199-218.
Papazachos, B.C., Comninakis, P.E., Scordilis, E.M., Karakaisis, G.F., and Papazachos, C, 2006. A catalogue of earthquakes in the Mediterranean and surrounding area for the period 1901-2005, Publication of the Dept of Geophysics, University of Thessaloniki.
Papazachos, C.B., and Kiratzi, A.A., 1996. A detailed study of active crustal in the Aegean and surrounding region, 1996, Tectonophysics, 253, 129-153.
Papazachos, C.B., and Nolet, G.P., 1997. Ρ and S deep velocity structure of the Hellenic area obtained by robust nonlinear inversion of travel times, J. Geophys. Res., 102, 8349-8367.
Wessel, P., and Smith, W.H.F., 1995. New version of the Generic Mapping Tools released, Eos, Trans. - Am. Geophys. Union 76, 329.
Yeats, et al, 1997.
Zoback, M.L., 1992. First- and second-order patterns of stress in the lithosphère: The World Stress Map project, J. Geophys. Res., 97, 11703-11728.
Articles les plus lus par le même auteur ou la même autrice