USGS fields tsunami questions after earthquake off Kodiak, Alaska

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USGS geophysicist Eric Geist fielded questions about tsunamis after a magnitude 7.9 earthquake off southern Alaska prompted a tsunami watch for the U.S. west coast.

The alert was issued shortly after midnight January 23 and canceled a few hours later, when coastal tide gauges and deep-ocean tsunami detectors had reported wave heights less than a foot. Fox 2/KTVU reporter Tom Vacar asked Geist about the possibility of a large tsunami hitting San Francisco’s Ocean Beach. Geist told him the largest credible wave would be 3 to 5 meters (10 to 15 feet) high, information that was included in the resulting news story. Those wave heights come from computer models in the SAFRR Tsunami Scenario, a scenario of a large hypothetical tsunami developed to assist emergency planning in California. The Kodiak earthquake struck close to the epicenter of the hypothetical scenario earthquake but on a different type of fault.

Map of Alaska and the surrounding ocean with the terrain and ocean floor in relief, star shows earthquake epicenter.
A magnitude 7.9 earthquake (yellow star) off southern Alaska on January 23 prompted tsunami alerts for Alaska, Canada, and the U.S. west coast. White circles show epicenters of past earthquakes, 1900-2015, the larger the circle size, the greater magnitude. Modified from USGS interactive map.
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