Steve Malone

steve@geophys.washington.edu

+1 206 685-3811

Department Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, U.S.A.

http://www.geophys.washington.edu/SEIS/PNSN/

In the review of focal mechanisms carried out by T. Qamar in December 1991 - January 1992 all events from 1970 through 1991 having ten or more picked first motions were run through the program focal with -f option (ie mechanism fit with program fpfit). Events having 10 or more polarities were found using program getfoc. A total of 2303 events were found having 10 or more polarites. 22 of these were not analyzed because their magnitude was less than 1.0. The remaining events were analyzed using focal and the mechanisms together with the plotted first motions were visually examined on summary sheets produced by program focm. Of the remaining 2,281 events, 1809 were judged to have acceptable double-couple mechanisms and 472 were judged to be unacceptable. Many of the early mechanisms were judged unreliable. A further review was carried on by Sandra Hebert in January 1996. All events from July 1993 through December 1995 were analyzed. Pickfiles with 10 or more first motions were selected by the script bestfocal written by Tony Qamar, and then run through focal -f -d (for pickfiles from July 93 to October 94) and focal2 (for pickfiles from November 94 to December 95). Focal mechanisms were plotted and visually examined, and mechanisms that were judged unreliable were removed.

List of data files