Pacific Northwest Geodetic Array
Central Washington University

Nisqually Earthquake

Mw 6.8 Earthquake in Washington State

The Nisqually earthquake which struck the Puget Sound area on February 28, 2001, poses the first opportunity to study an earthquake and its aftereffects in the Pacific Northwest using GPS geodesy. With assitance from UNAVCO and USGS/SCIGN, PANGA installed additional regional continuous GPS stations shortly after the event.

M. Meghan Miller testified before the Subcommittee on Research, The Committee on Science United States House of Representatives on Life in the Subduction Zone: The recent Nisqually Earthquake and Federal Efforts to Reduce Earthquake Hazards. For a full testimony click here [PDF]

  For a PDF of the February 28, 2001 Nisqually earthquake: GPS Geodesy and quantifying seismic hazard abstract click here [PDF]
 Information about PANGA rapid-response initiatives.

Quick-Response Continuous GPS Installations

Geophysical Modeling

Preliminary elastic half-space modeling of predicted horizontal surface displacements are now available, with vertical uplift contours. This model predicts the co-seismic deformation, about a maximum of 10 mm or 8 mm of vertical and horizontal surface displacments.

Model parameters:
Fault area: 30 km x 15 km
Strike 347°, dip 77°, slip -104
Epicenter: 47.167 -122.733
Depth: 59 km
Mw=6.8

GPS Results

 Nisqually Earthquake Displacements are available here.

Earthquake Information

Based on preliminary reports, it appears that the loss in the Nisqually earthquake will total about $2 billion. In terms of energy released, the earthquake was about one-third as strong as the 1949 earthquake. The earthquake occurred at a depth of about 53 km on a normal fault within the down-going Juan de Fuca plate.