The Nisqually earthquake occurred on February 28, 2001, and was one of the largest recorded earthquakes in Washington state history. The quake measured 6.8 on the Richter Scale and was centered about 17 km northeast of Olympia at a depth of 52km. Most of the property damage occurred very near the epicenter or in unreinforced concrete or masonry buildings, such as those in the Pioneer Square and Sodo neighborhoods of Seattle. There were no reports of deaths from the earthquake, but some sources state there was one death from a stress-related heart condition at the time of the earthquake.
The Puget Sound area where this earthquake occurred is prone to deep earthquakes due to the Juan de Fuca tectonic plate's subduction under the North American Plate, 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 6.5, depth 63km), and April 13, 1949 (magnitude 7.1, depth 53km).
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