HR: 1340h
AN: S33A-1048    [Abstracts]
TI: Variation in crustal structure in Iran and the surrounding region
AU: * Rham, D
EM: dr291@cam.ac.uk
AF: Bullard Laboratories, University of Cambridge, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ, United Kingdom
AU: Tatar, M
EM: mtatar@iiees.ac.ir
AF: IIEES, No. 26, Arghavan St., Farmanieh, Tehran, 19395, Iran (Islamic Republic of)
AU: Ashtiany, M
EM: mokhtari@iiees.ac.ir
AF: IIEES, No. 26, Arghavan St., Farmanieh, Tehran, 19395, Iran (Islamic Republic of)
AU: Mokhtari, M
EM: mokhtari@iiees.ac.ir
AF: IIEES, No. 26, Arghavan St., Farmanieh, Tehran, 19395, Iran (Islamic Republic of)
AU: Priestley, K
EM: keith@esc.cam.ac.uk
AF: Bullard Laboratories, University of Cambridge, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ, United Kingdom
AU: Paul, A
AF: LGIT, Universite Joseph-Fourier, 1381 rue de la Piscine, Grenoble, 38041, France
AB: We present a model for the topography of the Moho discontinuity for Iran and its surrounding regions. This is produced using data from field deployments within Iran by the University of Cambridge (UK) and the Universite Joseph-Fourier (FRA) in conjunction with International Institute of Earthquake Engineering and Seismology (Iran), in addition to data from IRIS and Geofone. We determine tomographic group velocity maps for periods between 10 and 60 s from multiple filter analysis of ~5500 seismograms. Because of the dense path coverage, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. Joint inversion of receiver functions and Rayleigh wave dispersion give accurate crustal velocity structures at 96 sites within Iran These provide a constraint for the less sharp crustal velocity profile produced by inverting the Rayleigh wave dispersion curve across all of Iran. We observe variations in the crustal thickness across the region, consistent with the surface topography. The thickest crust (55-60 km) is found beneath the central Zagros mountains, with the crust in the remainder of Iran having a thicknesses of 40-50 km. No significant increase in Moho depth is seen beneath the Alborz or Kopet Dagh mountains. The structure of the South Caspian Basin is presented with a different structure to that found in previous studies, with a crustal thickness of 50 km in the west, and beneath the Caucasus and Talesh mountains, in the middle part of the basin, over the course of the ~100km, this decreases to 40km, and continues to 35 km beneath the Turkmen Platform. Comparisons are also made between the joint inversion results, and accurate hypocentre depths for regional earthquakes. This shows most events occur in the upper crystalline crust (~10-20km depth), with few in the lowest velocity layer. Almost no events are located in the lower crust, and only in the Makran and Aspheron- Balkhan Sill do earthquakes appear in the Upper Mantle.
DE: 7203 Body waves
DE: 7205 Continental crust (1219)
DE: 7218 Lithosphere (1236)
DE: 7255 Surface waves and free oscillations
SC: Seismology [S]
MN: 2007 Fall Meeting