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Alaskan and Pacific Northwest coasts spared from tsunami, following 7.9 magnitude earthquake

This screenshot shows alerts for a tsunami watch early Tuesday, Jan. 23, 2018, after an earthquake struck off Alaska's Kodiak Island prompting a tsunami warning for a large swath of the state's coast. Officials at the National Tsunami Center canceled the warning after a few tense hours after waves failed to show up in coastal Alaska communities. (AP Photo)
This screenshot shows alerts for a tsunami watch early Tuesday, Jan. 23, 2018, after an earthquake struck off Alaska’s Kodiak Island prompting a tsunami warning for a large swath of the state’s coast. Officials at the National Tsunami Center canceled the warning after a few tense hours after waves failed to show up in coastal Alaska communities. (AP Photo)

Early Tuesday morning local time, a 7.9 magnitude earthquake occurred near Kodiak Island in the Gulf of Alaska. Officials across the Alaskan coast, as well as on the western coast of British Columbia, Canada were placed on tsunami alert, while the remainder of the Pacific Northwest states were on watch. In San Francisco, the Department of Emergency Management asked residents located within three blocks of the coast and five blocks of the bay to “prepare to evacuate.” 

At half past midnight, cellphones in Alaska buzzed with an emergency alert from the National Weather Service warning of an impending tsunami: “Emergency Alert. Tsunami danger on the coast. Go to high ground or move inland.” The Kodiak Police Department insisted that locals find an area located at least 100 feet above sea level. An officer discouraged travelling up to Pillar Mountain, situated approximately 1,240 feet above sea level, as it was reportedly backed up. This urged residents to move away from coastal areas and seek higher ground at their local high schools, town pools, and hospitals.

As the morning progressed, the tsunami alert was downgraded to an advisory as less than a foot of water hit the coast. At around 4 a.m., the United States National Tsunami Warning Center removed the tsunami advisory. Subsequently, watches were cancelled along Pacific Northwest states and in Canada.

The earthquake occurred in what is known as the “Ring of Fire,” a circle of tectonic plates that extends around most of the Pacific Ocean, creating some of the world’s most active earthquake zones, including Japan. Although Alaska escaped this earthquake unscathed, this is not the first time that Alaska and the Pacific Northwest faced the threat of a tsunami. In 1964, a 9.2 magnitude earthquake shook the Pacific Northwest and the west coast of Canada for 4.5 minutes, causing local tsunamis, landslides, and submarine slumps. Southeastern Alaska, the western coast of Canada, and the West Coast of the US sustained millions of dollars in damage to infrastructure, including roads and bridges.

Over the past several decades, scientists and emergency managers in the region have developed a greater understanding of the earthquake threat to the Pacific Northwest. Between ground shaking and tsunamis, they have determined that coastal communities west of the I-5 corridor are specifically vulnerable to earthquakes of this magnitude because they will become completely isolated from electricity, fuel, and emergency responders due to extreme damage to transportation infrastructure.

Cascadia Rising, a FEMA-led exercise designed to test the region’s ability to respond to a major earthquake, highlighted that many main ground corridors and critical infrastructure will be destroyed in the earthquake along the Pacific Northwest coast. The four-day, large scale exercise kicked off on June 7, 2016, and saw more than 20,000 emergency managers in Idaho, Oregon and Washington take part.

“The Cascadia Rising 2016 exercise highlighted a number of critical areas that we, the emergency management community, should improve before this fault ruptures, which will impact large portions of our residents and infrastructure,” said Sharon Loper, Acting FEMA Region 10 Administrator, one year after the 2016 exercise. “It is exercises like this, that foster coordination and help build relationships before a real-world event occurs. The exercise highlighted a number of infrastructure interdependencies our residents have come to rely on, such as electricity, communications, fuel, water and our roads.  Most of these sectors would be heavily disrupted after a CSZ event and plans are being developed and exercised that focus on the efficient recovery of these essential services.  In this past year, FEMA Region 10 has made improvements in coordinating disaster logistics, family reunification strategies and mass power outage scenarios with our partners.”

Suggested Reading

Post-quake tsunami alerts lifted for Alaska, British Columbia, U.S. West Coast – CBSNews

San Francisco DEM – Twitter

NBC Nightly News with Lester Holt – Twitter

Pillar Mountain – Alaska Guide

Tsunami Advisories Lifted After Alaska Earthquake – New York Times

1964 Alaskan Tsunami – University of Southern California