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 ZERVAS, C. E. Articles by CROSSON, R. S. Search for Related Content GeoRef GeoRef Citation

P_n observation and interpretation in Washington

GEOPHYSICS PROGRAM UNIVERSITY OF WASHINGTON, SEATTLE, WASHINGTON 98195

Abstract

The travel-time characteristics of P_n waves in the state of Washington were investigated using regional earthquakes as seismic sources and stations of the state-wide University of Washington telemetered network as receivers. There is a significant difference in upper mantle velocity between eastern Washington (8.20 ± 0.02 km/sec) and western Washington (7.79 ± 0.02 km/sec). Modifications of the time-term method were used to find the dependence of P velocity on distance and azimuth to the source. P_n velocity in eastern Washington depends on the distance to the source, implying a velocity gradient with depth in the upper mantle. No significant distance dependence was found for western Washington. Azimuthal anisotropy was found for P_n with a northwest direction of maximum velocity in eastern Washington and a north-northwest direction in western Washington. Assuming no lateral crustal velocity gradients, the P_n refracting interface dips to the west approximately 0.8° in eastern Washington and to the southeast approximately 3.2° in western Washington. Contour maps of the station time terms indicate significant variations in crustal structure across the state. The combination of low P_n velocity and small Moho dip beneath western Washington suggests that the subducting lithospheric slab underlying the continental margin lies below the level of transition to upper mantle velocity over much of this region.

This article has been cited by other articles:

				J. HAVSKOV, S. MALONE, D. MCCLURG, and R. CROSSON Coda Q for the state of Washington Bulletin of the Seismological Society of America, August 1, 1989; 79(4): 1024 - 1038. [Abstract] [PDF]

				T. J. OWENS, R. S. CROSSON, and M. A. HENDRICKSON Constraints on the subduction geometry beneath western Washington from broadband teleseismic waveform modeling Bulletin of the Seismological Society of America, June 1, 1988; 78(3): 1319 - 1334. [Abstract] [PDF]