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What happened to the tsunami? Too deep – but don’t be fooled. A large EQ in Alaska could seriously damage California coastlines!

California Tsunami RiskLast weeks massive, 7.9 Alaska earthquake turned out to be too deep (71 miles) to cause a tsunami on the West Coast of the United States. But seismic experts have long warned that a massive quake in Alaska could cause damaging wave activity along the California coast. Last year, USGS released a study detailing such a likely scenario.

The study was modeled on a 9.1 Alaska earthquake, bigger and shallower than last weeks. The report said such a quake could cause a tsunami that would damage California harbors and cause mass evacuations. The report details that in California marinas, one third of the boats could be damaged or sunk and two thirds of the docks damaged or destroyed, resulting in at least $700 million of loss. The report included a video showing how a tsunami formed by a big Alaska quake would hit the California.

The report is an analysis of the potential impacts along the California coast, intended for those who need to make mitigation, preparedness, and outreach decisions before tsunamis and those who will need to make rapid decisions during and after tsunamis. Some of the key findings include:

  • Distant tsunamis, although not as life-threatening as a large local event, can still lead to billions of dollars in losses in California.
  • The largest economic impacts to the state pertain to damage and incapacitation of our ports and harbors, and damages to coastal properties.
  • In California marinas, one third of the boats could be damaged or sunk and two thirds of the docks damaged or destroyed, resulting in at least $700 million of loss.
  • One quarter of a million people live in the maximum inundation zones mapped by the State of California and would likely be evacuated. An additional quarter of a million tourists and visitors may be on the coast if the scenario were to occur in March (tourist numbers could increase into the millions during the summer months).
  • 8,500 residents in the SAFRR Tsunami Scenario inundation zone would likely need shelter because of damage to their homes. Evacuations will also be a challenge for certain areas with limited access and dependent-care populations.
  • Visitors, in particular, are not typically well-educated about tsunamis, and often only those living in areas having recently experienced a tsunami have been educated. Everyone visiting and living near the beach should know their vulnerability and what to do (e.g., know where the closest high ground is and how to reach it).

Screen Shot 2014-06-27 at 10.41.54 AMThere is however a bit of good news in all of this doom and gloom:

  • Three-quarters of California’s coastline is cliffs and thus protected from many of the impacts of tsunamis.
  • Neither of California’s nuclear power plants are damaged in this scenario.
  • Ports and other sectors have the capacity to reduce the economic impacts in California, and this report outlines the potential effectiveness of resilience strategies in place that can be implemented to do so.


Download the report

Check out the video


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