Nisqually earthquake
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|
 Olympia
Seattle
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| Date | February 28, 2001 |
|---|---|
| Origin time | 18:54:32 UTC |
| Magnitude | 6.8 Mw |
| Depth | 57 km (35 mi) |
| Epicenter | 47°11′N 122°40′W / 47.19°N 122.66°WCoordinates: 47°11′N 122°40′W / 47.19°N 122.66°W |
| Type | Dip-slip |
| Areas affected | Pacific Northwest |
| Total damage | $1–4 billion |
| Max. intensity | VIII (Severe) |
| Peak acceleration | .3g |
| Casualties | 0–1 dead, 400 injured |
The 2001 Nisqually earthquake (also commonly referred to as "The Ash Wednesday earthquake") occurred at 10:54:32 local time on February 28. The intraslab earthquake had a moment magnitude of 6.8 and a maximum Mercalli intensity of VIII (Severe). The epicenter was in the southern Puget Sound, northeast of Olympia, but the shock was felt in Oregon, Canada, eastern Washington, and Idaho. This was one of several large earthquakes that occurred in the Puget sound region in the prior 52 years and caused property damage valued at between one and four billion dollars. One person died of a heart attack and several hundred were injured.
The Puget Sound area is prone to deep earthquakes due to the Juan de Fuca tectonic plate's subduction under the North American Plate at 3.5 to 4.5 cm a year as part of the Cascadia subduction zone, which causes stress in the former as it sinks into the mantle. Similar significant earthquakes occurred in the same general region on April 29, 1965 (magnitude 6.7, depth 59 km (37 mi)), and April 13, 1949 (magnitude 6.7, depth 50 km (31 mi)).
Although there were no directly-related deaths, local news outlets reported that there was one death from a heart attack. About 400 people were injured. Most of the property damage occurred very near the epicenter or in unreinforced concrete or masonry buildings, such as those in the First Hill, Pioneer Square and Sodo neighborhoods of Seattle. The Trinity Parish Church on First Hill was severely damaged. The air traffic control tower at Sea–Tac Airport was heavily damaged; it has since been replaced with a more earthquake-resistant tower. The quake splintered a buttress under the dome of the capitol building in Olympia, but previous earthquake-resistance work prevented more serious harm to the building. Additionally, power outages affected downtown Seattle. The U.S. Military's Ft. Lewis and McChord Air Force Base received damage and there was very slight damage in Victoria, British Columbia.
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Wikipedia