Open-File Report 01-266
A magnitude 6.8 earthquake struck southern Puget Sound, Washington, USA on February 28, 2001 causing an estimated $0.7 billion to $1.4 billion in damages to the surrounding area (Williams et al, 2001). The epicenter was close to the Nisqually delta, one of three major deltas in southern Puget Sound (Figure 1). The Nisqually delta is a wildlife refuge but the other two deltas, the Duwamish delta in Seattle and the Puyallup delta in Tacoma, support extensive infrastructure, including major port facilities at the delta edges. Teams of geologists inspected the area immediately after the earthquake and reported liquefaction features and areas of vertical ground displacement in the Ports of Seattle and Tacoma as well as the presence of "mud plumes" in the waters of Puget Sound. A joint NOAA/USGS cruise was rapidly assembled in March 2001 (3/19/01 to 3/30/01) to map the bathymetry of the delta fronts using the high-resolution multibeam systems of the NOAA Ship Rainier. The mapping discovered a variety of submarine failures on the Puyallup and Duwamish delta fronts that may be related to the earthquake.
First posted June 5, 2001
For additional information, contact:
Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge.
Gardner, James V., van den Ameele, E. J., Dartnell, Peter, 2001, Multibeam Mapping of the Major Deltas of Southern Puget Sound, Washington: U.S. Geological Survey Open-File Report 01-266, http://pubs.usgs.gov/of/2001/0266.