16 BB, 3 component seismtrs. with high gain digital recorders were deplyd. inthe Puget Sound region of WA. The array was oriented eas-west, stretching from the eastern foothills of the Olympic Mtns. to the western foothills of the Cascade Mnts. at the latitude of Seattle. West of Seattle, the station spacing was approximately 4 Kl. Data were collected continuously from early Feb. through April, 1994. Data collection rates were 20 sps and 1 sps. The prinicple pupose of the sxp. is to identify and study upper mantle and crustal structures in the Puget Sound area by analyzing receiver functions.