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S-P wave travel time residuals and lateral inhomogeneity in the mantle beneath Tibet and the HimalayaS-P wave travel time residuals were measured in earthquakes in Tibet and the Himalaya in order to study lateral inhomogeneities in the earth's mantle. Average S-P residuals, measured with respect to Jeffrey-Bullen (J-B) tables for 11 earthquakes in the Himalaya are less than +1 second. Average J-B S-P from 10 of 11 earthquakes in Tibet, however, are greater than +1 second even when corrected for local crustal thickness. The largest values, ranging between 2.5 and 4.9 seconds are for five events in central and northern Tibet, and they imply that the average velocities in the crust and upper mantle in this part of Tibet are 4 to 10 percent lower than those beneath the Himalaya. On the basis of the data, it is concluded that it is unlikely that a shield structure lies beneath north central Tibet unless the S-P residuals are due to structural variations occurring deeper than 250 km.
Document ID
19840061093
Document Type
Reprint (Version printed in journal)
Authors
Molnar, P. (MIT Cambridge, MA, United States)
Chen, W.-P. (Illinois, University Urbana, IL, United States)
Date Acquired
August 12, 2013
Publication Date
August 10, 1984
Publication Information
Publication: Journal of Geophysical Research
Volume: 89
ISSN: 0148-0227
Subject Category
GEOPHYSICS
Funding Number(s)
CONTRACT_GRANT: NAG5-141
CONTRACT_GRANT: NSF EAR-81-21184
Distribution Limits
Public
Copyright
Other