Accession Number : ADP204434

Title :   Propagation of Regional Phases in Southern Asia and the Middle East,

Corporate Author : SAINT LOUIS UNIV MO DEPT OF EARTH AND ATMOSPHERIC SCIENCES

Personal Author(s) : Mitchell, B. J. ; Pan, Y.

PDF Url : ADP204434

Report Date : 14 AUG 1995

Pagination or Media Count : 5

Abstract : 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.

Descriptors :   *SEISMIC DETECTION, *SEISMIC WAVES, *ARMS CONTROL, *NUCLEAR EXPLOSION DETECTION, SYMPOSIA, SURFACE WAVES, MIDDLE EAST, NUCLEAR EXPLOSION TESTING, WAVE PROPAGATION, SEISMIC DISCRIMINATION, TREATIES, MEDITERRANEAN SEA, ASIA, Q FACTOR, RAYLEIGH WAVES, RED SEA.

Subject Categories : Government and Political Science
      Seismology
      Seismic Detection and Detectors
      Nuclear Weapons

Distribution Statement : APPROVED FOR PUBLIC RELEASE