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.

Figure 1. Map of the Southern Puget Sound, Washington
region showing the February 28, 2001 earthquake epicenter
and the three delta regions mapped by the multibeam sonar systems.

This Open-File Report contains the multibeam bathymetry data collected during the NOAA/USGS cruise. The data are in two formats; ASCII XYZ and ArcInfo GRID (both at 3- or 4-m resolution). The report also contains an ArcView project (.apr) displaying the data at 3- or 4-m resolution, metadata, a PowerPoint presentation of the data, a short article describing the mapping of the deltas, and the cruise report from the NOAA/USGS cruise. The ASCII XYZ and ArcInfo GRID data are provided so that the data can be input and utilized to the users specifications in virtually any GIS. The ArcView project of the bathymetry for Nisqually, Puyallup, and Duwamish deltas is used for viewing and analyses. The PowerPoint presentation, article, and cruise report are included to provide background.

For more information, visit our Pacific Seafloor Mapping website.

References:

Williams, C.R., Windeler, D.S., Rahnama, M., Morrow, G.C., and Rodriguez, A., 2001, Insured loss estimates for the 28 February 2001 Nisqually earthquake. Seismological Soc. Amer. Ann. Mtg., San Francisco, CA.

The multibeam bathymetry data are in two formats; ASCII XYZ and ArcInfo GRID (both at 3- or 4-m resolution). FGDC metadata is provided for each format and and is available in three different forms, FAQ (Frequently Anticipated Questions), HTML, and text.

DUWAMISH DELTA
ASCII XYZ
FAQ
HTML
TEXT

ArcInfo GRID
FAQ
HTML
TEXT

PUYALLUP DELTA
ASCII XYZ
FAQ
HTML
TEXT

ArcInfo GRID
FAQ
HTML
TEXT

NISQUALLY DELTA
ASCII XYZ
FAQ
HTML
TEXT

ArcInfo GRID
FAQ
HTML
TEXT