HR: 1340h
AN: S53B-0223    [Abstracts]
TI: Simultaneous Inversion of Receiver Functions and Surface Wave Dispersion For Lithospheric Structure Beneath The Middle East, North African, Central Asia, And Parts of Europe
AU: * Kosarian, M
EM: mkosari@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802 United States
AU: Sevilla, W
EM: wsevilla@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802 United States
AU: Ammon, C J
EM: cammon@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802 United States
AU: Herrmann, R B
EM: rbh@eas.slu.edu
AF: Saint Louis University, Department of Earth and Atmospheric Sciences, Saint Louis, MO 63103 United States
AU: Pasyanos, M E
EM: pasyanos1@llnl.gov
AF: Lawrence Livermore National Laboratory, L-205 P.O. Box 808, Livermore,, CA 94551 United States
AU: Randall, G
EM: grandall@lanl.gov
AF: Los Alamos National Laboratory, Los Alamos Seismic Research center, Los Alamos, NM 87545 United States
AB: Numerous researchers have studied lithospheric structure of Africa, Europe, the Middle East, and Asia for decades. Although there are agreements on the general lithospheric structure, interesting discrepancies exist on the specific lithospheric structure in a number of areas. Our objective is the construction of shear-wave velocity profiles for regions surrounding broadband seismic stations throughout the Middle East, central and north Africa, central Asia, and parts of Europe. This survey provides an opportunity to confirm and if needed, revise, models of the crust and upper mantle structure throughout the region. To estimate lithospheric structure, we use a joint inversion of receiver function and surface wave dispersion observations. We collected seismic data from available permanent and temporary three-component broadband seismic stations throughout the region. Two hundred and thirty-two stations, to date, have been investigated; 37 stations in central and north Africa, 72 stations in Middle East, 57 stations in Europe, and 66 stations in central Asia. We have examined receiver functions for 138 of stations in the period of 1990-2003, and have inverted a number using dispersion measurements extracted from global and regional tomographic models. We also applied the receiver function stacking procedure of Zhu and Kanamori [2000] to estimate Vp/Vs and crustal thickness. This initial analysis provides reasonable constraints on thickness and Poisson's ratio (which trade-off) for each station and helps identify stations situated in complex structures, where simple plate-layered interpretations fail. For most stations crustal thickness and Poisson's ratio vary as a function of back azimuth, indicating non-isotropic plane-layered structure. Crustal thickness for Middle East ranges from 32-56 km with a mean of 43 km. The average Vp/Vs value for the region is 1.73. Sites in Africa have a crustal thickness range of 27-55 km with a mean of 37 km and average Vp/Vs 1.76. For station in Asia we find a crustal thickness range of 28-80 km with a mean value of 53 km. The average Vp/Vs for this region is 1.75. For stations in Europe crustal thickness estimates range from 24-44 km with a mean of 33 km and an average value of 1.73 for Vp/Vs. The majority (but not all) of our crustal thickness estimates are consistent with previous geophysical/seismological work. The mean differences between our estimates and those of Crust 2.0 is about 1 km with a standard deviation of the differences is about 5 km. A comparison of the crustal thickness and Poisson's ratio estimates for the crust beneath these stations will be presented; also we will show a comparison of our results with present global crustal models.
DE: 7218 Lithosphere and upper mantle
SC: Seismology [S]
MN: 2004 AGU Fall Meeting