SEATTLE Ten years ago today, the Puget Sound region was rocked by the largest earthquake in decades, injuring more than 400 people and causing more than $500 million worth of damage.
Centered 30 miles southwest of Seattle, the 6.8 magnitude Nisqually quake struck at 10:54 a.m. on Ash Wednesday, Feb. 28, 2001.
In Seattle, Tacoma, and communities across the region, the ground shook for up to 40 seconds, sending people running for cover. The earthquake was felt as far away as Salt Lake City.
Damage was widespread. In Seattle alone, more than 600 buildings were damaged. One death was attributed to the quake and more than 400 people were hurt.
While the Alaskan Way Viaduct survived the quake, its joints and columns were damaged, further weakening the structure and revealing its vulnerability.
The quake disrupted gas, electric, and phone service and triggered landslides. Hundreds of chimneys toppled, and buildings with foundations resting on unstable soil or not tied to their foundations were shaken off their mountings.
The State Capitol dome was damaged and on Highway 101 betwen Shelton and Olympia, the quake opened up a major hole in the roadway.
While Seattle escaped major damage, piles of rubble blocked downtown sidewalks. The control tower at Sea-Tac Airport was destroyed and many buildings in the Pioneer Square and Sodo neighborhoods were damaged.
Scientists say in the decade since the Nisqually earthquake, the level of seismic danger in the Pacific Northwest hasn't changed, but scientific ideas about the danger have evolved and the ability to study and prepare for it has improved immensely.
Scientists from the University of Washington and the U.S. Geological Survey have increased their knowledge about the three different types of non-volcanic earthquakes that occur in the Northwest, and are learning how unfelt episodic tremor and slip events relate to seismic risk. The number of seismic sensors and the territory they monitor has tripled, and engineering standards have improved to meet the region's seismic risks.