Surface Wave Group Velocity Tomography of East Asia. Part 1
Final rept. 1 Feb 1992-1 Feb 1993
STATE UNIV OF NEW YORK AT BINGHAMTON DEPT OF GEOLOGICAL SCIENCE AND ENVIRONMENTAL STUDIES
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Group velocities of both Rayleigh and Love waves are used in a tomographic inversion to obtain group velocity maps of East Asia 60 deg E-140 deg E and 20 deg N-50 deg N. The period range studied is 30-70 seconds. For periods longer than 40 seconds, a high group velocity gradient clearly exists along longitude 105 deg E the velocities are noticeably higher east of this longitude than west of this longitude. The Tibetan Plateau appears as a prominent low velocity about 15 structure in this area central Tibet appears as the area with the lowest velocity. The North China Plain is an area of high velocities, probably as a result of thin crust. The variability of deep crustal and upper mantle structures underneath the different tectonic provinces in the study can clearly be seen. In a separate study, using the dataset above and that from the former Soviet Union, we have derived the Rayleigh tomographic images of a larger area 40 deg E-160 deg E and 20 deg N-70 deg N. While the Tibetan plateau still remains to be the most prominent low velocity features, two other features are also clear, a very high velocity Siberian platform and a high velocity ridge extending from Lake Baikal to Central Mongolia. These studies are useful in delineating tectonics.
- Geology, Geochemistry and Mineralogy