Investigating crustal structure in western Washington and in the Rocky Mountains: Implications for seismic hazards and crustal growth

Catherine Mary Snelson, University of Texas at El Paso

Abstract

This dissertation consists of two seismic studies, one in western Washington State and one in the Rocky Mountains. The study in western Washington State is one component of the SHIPS (Seismic Hazards Investigations of Puget Sound) experiments, a continuing effort to define Cenozoic basin and fault geometry beneath the densely populated Puget Lowland. In September 1999, the U.S. Geological Survey and a number of university collaborators collected the “Dry” SHIPS seismic profile across the Seattle basin of western Washington State. The objectives of the “Dry” SHIPS study were to define the geometry of the Seattle basin in an E-W direction and to determine the structure of the eastern and western boundaries of the basin. In addition, the experiment was designed to test the hypothesis that N-S trending faults lie beneath Puget Sound or the adjacent Lowland. One of these faults may form the eastern boundary of the Siletz terrane. The “Dry” SHIPS data are characterized by travel time advances associated with the Siletz terrane to the west and the Cascades to the east and by delays of as much as 2 s in the Seattle basin. ^ The study in the Rocky Mountains is one component of the Continental Dynamics-Rocky Mountains Project (CD-RoM '99), a collaborative interdisciplinary study involving 14 American universities and the University of Karlsruhe, Germany that focuses on Precambrian features and their effects on Phanerozoic deformation. One of the major field efforts in the CD-RoM project took place during August, 1999. The University of Texas at El Paso and the University of Karlsruhe, with the assistance of several other institutions, collected data along a ∼950 km long seismic refraction/wide-angle reflection profile extending from Fort Sumner, New Mexico to the Gas Hills, Wyoming. Station spacing was nominally 800 m using ∼600 instruments during two deployments. Eleven shots were fired ranging in size from 167.2–4540.9 kg and were nominally spaced at ∼100 km intervals along the profile. The profile crosses major structural features of the continent including the Jemez lineament, the Colorado mineral belt, and the Cheyenne belt (a prominent Proterozoic suture). (Abstract shortened by UMI.)^

Subject Area

Geology|Geophysics

Recommended Citation

Snelson, Catherine Mary, "Investigating crustal structure in western Washington and in the Rocky Mountains: Implications for seismic hazards and crustal growth" (2001). ETD Collection for University of Texas, El Paso. AAI3035102.
http://digitalcommons.utep.edu/dissertations/AAI3035102

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