Propagation of Regional Phases in Southern Asia and the Middle East,
SAINT LOUIS UNIV MO DEPT OF EARTH AND ATMOSPHERIC SCIENCES
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New Lg coda Q values have been determined for Iran using the stacked spectral ratio method. These, combined with values obtained earlier by Ghalib 1992 in the Arabian penninsula and by John 1983 in India, allow us to extend Lg coda Q coverage through much of southern Asia and the Middle East. With the exception of the Indian shield, Q is low throughout all of the region of study. Lg coda Q in the Indian shield is about 1000 but observed values decrease rapidly with distance to the north and west of the shield, being as low as 200 in Pakistan. Lg coda Q is low throughout all of the Middle East with values ranging between about 150 and 300. That variability may be partly due the lateral structural complexity of the region. Portions of some scattering ellipses for the Lg coda data overlap oceanic regions the Red Sea and the eastern Mediterranean Sea, a situation that has been shown to systematically affect Lg coda Q measurements. We plan to incorporate these Lg coda Q results into inversions of fundamental-mode Rayleigh wave attenuation to obtain frequency-dependent models of shear-wave internal friction for various regions of the Middle East.
- Government and Political Science
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