ABSTRACT The main purpose of the paper is assessing the three-dimensional (3-D) seismic tomography beneath Egyptto reveal the laws of the tectonic activity, dynamic features of the crust and the upper mantle as well as the thermal structure. Thecoda wave attenuation (Q-1c ) was obtained using the single scattering theory for the central frequencies of interest laid between 1 and 24 Hz. A regionalization of the estimated Q-1c values was performed by means of a generalized inversion technique.The obtained spatial distribution of 3-D attenuation results revealshigh contrasts between East and West Egypt. A remarkable contrast in the attenuation levels was compared with the tectonic structures, geothermal gradient and heat flow features. The highest attenuations are concentrated in the east and north western offshore regionsat central frequency 1.5 Hzthat draw a good matching with the seismic andthermal features of Egypt. Smaller attenuation levels were detected with young sediments of the Nile Valley from South to the northern triangle of Nile Delta basin except seismic active areas. Low or normal attenuation was detected at western desert where there is a stable and simple shelf. We can conclude that the extended highest attenuation joins to the strong seismic sources and geothermal structures at lower frequency and the centralized high attenuation takes place at moderate seismic sources at a higher frequency. The 3D attenuation maps can draw not only tectonic and geothermal structures but also the general geologic structure map.
Cite this paper
Fergany, E. , Abass, M. and Vargas, C. (2012) Three-dimensional seismic attenuation tomography of Egypt. Natural Science, 4, 608-623. doi: 10.4236/ns.2012.428081.
 Frankel, A. (1990) Attenuation of high-frequency shear waves in the crust: Measurements from New York State, South Africa, and Southern California. Journal of geophysical research, 95, 17441-17457.
 Baker, G.E., Stevens, J. and Xu, H.M. (2004) Lg group velocity: A depth discriminant revisited. Bulletin of the Seismological Society of America, 94, 722-739.
 Mayeda, K., Hofstetter, A., O’Boyle, J.L. and Walter, W.R. (2003) Stable and transportable regional magnitudes based on coda-derived momentrate spectra. Bulletin of the Seismological Society of America, 93, 224-239.
 Taylor, S., Velasco, A., Hartse, H., Philips, W.S., Walter, W.R. and Rodgers, A. (2002) Amplitude corrections for regional discrimination. Pure and Applied Geophysics, 159, 623-650. doi:10.1007/s00024-002-8652-8
 Aki, K. (1969) Analysis of the seismic coda of local earthquakes as scattered waves. Journal of geophysical research, 74, 615-631. doi:10.1029/JB074i002p00615
 Aki, K. and Chouet, B. (1975) Origin of coda waves: source, attenuation and scattering effects. Journal of geophysical research, 80, 615-631.
 Chen, X. and Aki, K. (1991) General coherence functions for amplitude and phase fluctuations in a randomly heterogeneous medium. Geophysical Journal International, 105, 155-162. doi:10.1111/j.1365-246X.1991.tb03451.x
 Frankel, A. and Wennerberg, L. (1987) Energy-flux model of seismic coda: Separation of scattering and intrinsic attenuation. Bulletin of the Seismological Society of America, 77, 1223-1251.
 Hoshiba, M. (1991) Simulation of multiple scattered coda wave excitation based on the energy conservation law. Physics of the Earth and Planetary Interiors, 67, 123-136.
 Matsunami, K. (1991) Laboratory tests of excitation and attenuation of coda waves using 2-D models of sacattering media. Physics of the Earth and Planetary Interiors, 67, 36-47. doi:10.1016/0031-9201(91)90058-P
 Vargas, C.A., Ugalde, A., Pujades, L. And Canas, J. (2004) Spatial variation of coda wave attenuation in northwestern Colombia. Geophysical Journal International, 158, 609-624. doi:10.1111/j.1365-246X.2004.02307.x
 Singh, S. and Herrmann, R.B. (1983) Regionalization of crustal coda Q in the continental United States. Journal of geophysical research, 88, 527-538.
 Jin, A. and Aki, K. (1988) Spatial and temporal correlation between coda Q and seismicity in China. Bulletin of the Seismological Society of America, 78, 741-769.
 Mamdouh, A., Marzouk, I., Maher, M. and El-Rayes, M. (2008) An evidence of neotectonics in Sinai Peninsula, Egypt. NRIAG Journal of Geophysics, Special Issue, 1-20.
 Mamdouh, A. and Fergany, E. (2009) Coda-wave attenuation study in North Egypt using Mediterranean earthquakes. NRIAG Journal of Geophysics, Special Issue, 67-82.
 Mamdouh, A., Sherif, E., Salah, M. and Enayat, A. (2011) Lateral variations of coda Q and attenuation of seismicwaves in the Gulf of Suez, Egypt. Arabian Journal of Geosciences, 1-11. doi:10.1007/s12517-011-0302-y
 Sato, H. (1977) Energy propagation including scattering effects single isotropic scattering approximation. Journal of Physics of the Earth, 25, 27-41.
 Malin, P.E. (1978) A first order scattering solution for modeling lunar and terretrial seismic coda. Ph.D. Thesis, Princeton University, Princeton.
 McKenzie, D.P. (1972) Active tectonics of the Mediterranean region. Geophysical Journal of the Royal Astronomical Society, 30, 109-158.
 Makris, J. (1976) A dynamic model of the Hellenic arc deduced from geophysical data. Tectonophysics, 36, 339-346.
 Le Pichon, X., Augustithis, S.S. and Mascle, J. (1982) Geodynamics of the Hellenic Arc and Trench. Tectonophysics, 86.
 Egyptian Geological Survey and Mining Authority (1981) Geologic map of Egypt 1:2000000. EGSMA, Cairo.
 Sofratome Group (1984) El-Daba nuclear power plant, NPPA. Ministry of Electricity, Cairo.
 Salamon, A., Hofstetter, A., Garfunkel, Z. and Ron, H. (1996) Seismicity of the eastern Mediterranean region: perspective from the Sinai subplate. Tectonophysics, 263, 293-305. doi:10.1016/S0040-1951(96)00030-3
 Riad, S. and Meyers, H. (1985) Earthquake catalog for the Middle East Countries 1900-1983. World Data Center for Solid Earth Geophysics, Rep. SE-40, National Oceanic and Atmospheric Administration (NOAA), US Department of Commerce, Boulder.
 Muffler, L.P.J. (1976) Tectonic and hydrologic control of the nature and distribution of geothermal resources. Proceedings of Second U.N. Symposium on the Development and Use of Geothermal Resources, 1, 499-507.
 United Nations (1976). Present status of world geothermal development. Proceedings of Second United Nations Symposium of the Development and Use of Geothermal Resources, 1, pp. 3-9.
 Le Pichon, X., Francheteau, J. and Bonnin, J. (1973) Plate tectonics. Elsevier Scientific Pub. Co., Amsterdam, 300.
 AbouElenean, K.M. (1997) A study on the seismotectonics of Egypt in relation to the Mediterranean and Red Seas tectonics. Ph.D. Thesis, Ain Shams University, Cairo.
 AbouElenean, K. and Hussein, H. (2007) Source mechanism and source parameters of May 28, 1998 earthquake, Egypt. Journal of Seismology, 11, 259-274.
 Morgan, P. and Swanberg, C.A. (1979) Heat flow and the geothermal potential of Egypt. Pure and Applied Geophysics, 117, 213-226. doi:10.1007/BF00879748
 Ibá?ez, J.J., Jiménez-Ballesta, R. and García-Alvarez, A. (1990) Soil landscapes and drainage basins in Mediterranean mountain areas. Catena, 17, 573-583.
 Pulli, J.J. (1984) Attenuation of coda waves in New England. Bulletin of the Seismological Society of America, 74, 1149-1166.
 Crosson, R.S. (1976) Crustal structure modeling of earthquake data 1. simultaneous least squares estimation of hypocenter and velocity partameters. Journal of geophysical research, 81, 3036-3046.