Tsunami Preparedness
in the PNW and Seattle
A tsunami (pronounced tsoo-nah-mee) is a series of waves, generated in a body of water by a disturbance that moves the whole water column. A tsunami can be caused by many climatic events; earthquakes, landslides, volcanic eruptions, explosions, and even the impact of cosmic bodies, such as meteorites. As we witnessed globally in 2004, Tsunamis can cause devastating property damage and loss of life.
The epicenter of the 2004 9.0 magnitude quake in the Indian Ocean was near the west coast of Sumatra. Within hours of the 2004 Indian Ocean earthquake, killer waves radiating from the epicenter slammed into the coastlines of 11 countries, damaging coastline cities and beaches from east Africa to Thailand. Many people in Indonesia reported that they saw animals fleeing for high ground minutes before the tsunami arrived – very few animal bodies were found afterward, whereas hundreds of thousands of lives were lost (estimates of at least 227,898 fatalities) due to a lack of tsunami warnings and overall personal preparedness.
The last recorded great PNW earthquake occurred on January 26, 1700 and produced a tsunami that took lives in our region, across the Pacific along the coast of Japan and elsewhere. More recently, the historic Alaska tsunamis of 1946 and 1964, brought to light the general lack of tsunami preparedness and hazard assessment for the U.S. west coast and the need for significant improvement in tsunami detection and forecasting. As a result, there have been many improvements in Regional Awareness and organization for emergency situations. The first comprehensive inundation Tsunami Hazard Mapping in the Cascadia Region began after the creation of the National Tsunami Hazard Mitigation Program (NTHMP).
On February 20, 2010, a magnitude 8.0 earthquake hit the coast of Chili in South America. No significant tsunami wave arrived on the west coast, and Hawaii experienced smaller wave than predicted (2-3 feet vs. original estimate of ~ 10 feet). This recent event reminded the residents of the Cascadia Region that a locally generated tsunami will be a major threat to coastal residents along the entire west coast including British Columbia, Washington, Oregon and California.
The Tohuku Japan Magnitude 9.1 earthquake on Friday, March 11th, 2011 provided horrifying images of great waves smashing through the best coastal defenses in the world and into the heart of coastal cities laying waste to everything in its path. Japanese scientists made a serious mistake in thinking that a few hundred years of history defined the limit of how large earthquakes in the Japan Trench subduction zone could get. Maximum wave height in Miyako tsunami was reported as reaching 133 feet.
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