|Headline from the Seattle Post-Intelligencer, March 1, 2001.|
|Earthquake occurrences in the past seven days.|
(Screen grab from www.usgs.gov)
Today is the 10th anniversary of the magnitude 6.8 Nisqually earthquake, which struck the area at 10:54 a.m. local time on Wednesday, February 28, 2001. Although it ranks as only the 82nd largest earthquake by magnitude (by my count) in the U.S., it is the third largest on record and the most recent significant quake in Washington state.
The quake originated at a depth of 52 km in the subsurface Juan de Fuca plate, which is subducting under the North American plate in the Cascadia subduction zone. The epicenter (47.15N 122.72W) was located toward the southern end of Puget Sound, 17.6 km northeast of Olympia, WA and 57.5 km south southwest of Seattle.
|Zip code by zip code view of Mercalli Scale intensity of the|
earthquake in the Puget Sound region. (map by USGS)
|Highway 302 near Olympia, WA following the 2001Nisqually|
earthquake. (photo by USGS via Wikipedia)
Although it seems that we have had too many recent reminders worldwide of the devastation that can be caused by large earthquakes, the 2001 Nisqually event brought much-needed attention to the threat posed to the Pacific Northwest. In the 10 years since, significant efforts have been made to better equip the city for future earthquakes. These efforts are ongoing and include helping homeowners retrofit their houses to withstand strong shaking and potentially replacing the Alaskan Way Viaduct. The biggest seismic threat for the area is thought to be posed by either a massive subduction zone earthquake along the JDF-NA plate boundary, or a shallow earthquake on the local Seattle Fault, which runs beneath the city.
A sampling of additional material and links for the interested reader:
Coverage on the 10th Anniversary
- Seattle Times: Live chat at 12:30 p.m. (Seattle time) on March 1 with Times writer Sandi Doughton, John Vidale, head of the UW Seismology Network and Roger Faris, an instructor for the city of Seattle's earthquake retrofit classes for homeowners; Much more coverage from the Times here.
- Seattle Post-Intelligencer: February 28, 2001 and One year anniversary coverage (lots of great figures)
- PBS Online Newhour
- Science News - April 10, 2009
- Discovery News - April 9, 2009
- Physorg.com - April 16, 2009
- Discovery News - March 7, 2010
- NY Times - March 27, 2010
From National Geographic via YouTube:
Simulation of an Earthquake of Magnitude 7.0 occurring closer to Seattle than the Nisqually quake - from the Washington state Department of Transporation via YouTube:
Nisqually Earthquake Photo Galleries
- Seattle Fault Scenario from the Earthquake Engineering Research Institute
- Tsunami Hazard Map for Elliot Bay area from the Washington state DNR and NOAA
- USGS Nisqually quake pages here and here among others
- Pacific Northwest Seismic Network (PNSN) information about 2001 quake and local earthquake scenarios
- Seattle Office of Emergency Management
- Nisqually Earthquake Information Clearinghouse