Two studies in central Asian seismology:

مرکز و کتابخانه مطالعات اسلامی به زبان های اروپایی

منو

" Two studies in central Asian seismology: "
R. J. Mellors

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1113259
Doc. No	:	TLpq304200582
Main Entry	:	R. J. Mellors
Title & Author	:	Two studies in central Asian seismology:\ R. J. Mellors
College	:	Indiana University
Date	:	1995
student score	:	1995
Degree	:	Ph.D.
Page No	:	224
Abstract	:	The thesis consists of two separate studies: (1) an analysis of lateral velocity variations associated with the Pamir and Hindu Kush seismic zones and (2) a study of the seismicity and tectonics of the Kyrgyz Tien Shan, with emphasis on a major earthquake and its aftershock sequence. In the first study, I used teleseismic arrival time data from analog seismic stations in Tadjikistan and northern Afghanistan to invert for velocity perturbations in the crust and upper mantle of the Pamir-Hindu Kush. The results show a strong (up to 6%) well-resolved zone of high velocities in the upper mantle at depths greater than 200 km, coincident with the location of the deep Hindu Kush earthquakes. I interpret these high velocities under the Hindu Kush as evidence of oceanic lithosphere at depth. The second study concentrated on data from 10 telemetered broadband seismometers installed in the area around Bishkek, Kyrgyzstan. A range of phenomena were observed. These include: (1) a ramp-like phase between the P and the S wave arrivals that is observed nearby (<15 km distance) events possibly due to near-field source terms; (2) a pronounced vertical displacement signal that coincides with the arrival of the S wave for a number of high-amplitude local events; (3) strong variations in aftershock waveforms that appear to be dependent in part on source depth; and (4) variations in S wave amplitude across the network from regional events. The Ms 7.4 Suusamyr, Kyrgyzstan earthquake of 19 August 1992 was studied using aftershock data, a teleseismic body wave inversion, and field observations. The combined analysis defined a 50 km-long, east-west rupture zone that dips 50 to the south and extends to a depth of 18 km. The rupture originated at the eastern end at depth and propagated westward, and probably included at least one sub-event. The Suusamyr event demonstrates that a large amount of current shortening is accommodated along high-angle reverse faults within the Tien Shan.
Subject	:	Earth sciences
	:	Geophysics