GPS Monitoring of Upcoming Cascadia Episodic Tremor and Slip Event

Overview

August 22, 2005

With 10 GPS stations recently installed across the northern Olympic Peninsula, the campaign GPS deployment to monitor the imminent Cascadia episodic tremor and slip event is underway. On August 4, 2005, permitting was completed for GPS installations in Olympic National Park where the bulk of the sites on the peninsula will be located. Since then, four GPS stations have been installed in the park and another 20 GPS units are scheduled for deployment in the Olympic Peninsula and Puget Sound regions in upcoming weeks.

The project, entitled “Stalking Cascadia Episodic and Slip with Enhanced GPS and Seismic Arrays,” is the first EarthScope funded use of the new UNAVCO supported pool of Topcon GB-1000 GPS systems. By using a dense array of GPS and broadband seismic equipment, principal investigators Ken Creager and Dan Johnson of the University of Washington, and Rick Bennett of the University of Arizona, hope to improve understanding of the periodic slow earthquakes that have been recently discovered to occur in the Cascadia subduction zone. The deployment is expected to be completed by mid-August and will last up to three months or until the ETS event has completed.

The GPS installation design consists of an antenna mounted on a single galvanized steel rod that is driven 2-4 feet below the surface. The short antenna mount (only 1-2 feet above ground) and the high density of GPS sites being deployed will compensate for any monumentation instability. This design was chosen for ease of removal and to comply with the National Park Service’s “Leave No Trace” ethics.

Additional information on the Cascadia Episodic Tremor and Slip project can be found at http://www.pnsn.org/WEBICORDER/DEEPTREM/summer2005.html.