HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) References Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by MENKE, W. H. Search for Related Content GeoRef GeoRef Citation

Lateral inhomogeneities in P velocity under the Tarbela array of the lesser Himalayas of Pakistan

LAMONT-DOHERTY GEOLOGICAL OBSERVATORY OF COLUMBIA UNIVERSITY, PALISADES, NEW YORK 10964

Abstract

Three-dimensional seismic-velocity heterogeneities (to a depth of 125 km) under the Tarbela array are determined by the Aki et al. (1976a) method of inverting teleseismic travel-time residuals. Velocity anomalies are clearly present and are elongated in the northwest direction. An overall 2 to 3 per cent decrease in velocity to the northeast is observed across any horizontal layer. These features result from a 4° dip of geologic structures in the direction N41°E. This direction is similar to some observed trends of seismicity in the Tarbela area and to the trend of the Himalayan Main Central Thrust (MCT) east and north of Tarbela, but not to the trend of the fault traces nor the strike of geologic structures in the Tarbela area. Just to the southeast of the Tarbela array, these faults bend sharply westward, forming a mountainous loop. In this study it is concluded that the westerly trending fault traces and westerly striking geology are both only surficial and not representative of structures at greater depth. These deep structures within the lower crust and upper mantle preserve a strike similar to more eastern areas along the MCT. They are shown to be volumetrically and tectonically the more important features.

This article has been cited by other articles:

				Development and Testing of a 3D Velocity Model for Improved Event Location: A Case Study for the India-Pakistan Region Bulletin of the Seismological Society of America, December 1, 2002; 92(8): 2893 - 2910.

				R. D. SINGH, V. P. SINGH, and J. SINGH Love wave propagation in a transversely anisotropic and laterally inhomogeneous N-layered model Bulletin of the Seismological Society of America, October 1, 1984; 74(5): 1579 - 1591. [Abstract] [PDF]