TSUNAMI HAZARD MITIGATION FOR ALASKA

Coastal Alaska lives with the most serious tsunami risk in the United States. Historically, tsunamis generated by earthquakes in Alaska have caused damage and loss of life along the West Coast and across the Pacific. Here in Alaska, though, tsunamis generated by nearby earthquakes represent “near-field” hazards. In other words, people have minutes rather than hours to reach safety.

The Earthquake Center works to make our coastal communities safer by providing state and local officials with the best possible information for addressing the tsunami hazards faced by their communities.

Click on the map at right to explore our interactive mapping interface. Zoom to your area of interest by selecting a community and map type. You can also toggle between map and satellite views at the top right. At present, the interactive map includes flow depths and inundation boundaries for 21 at-risk communities.

INUNDATION MAPPING PROJECT

In partnership with the Alaska Division of Geological and Geophysical Surveys and the Alaska Division of Homeland Security and Emergency Management, we evaluate and map potential inundation using numerical modeling of tsunami wave dynamics.

Communities are selected with consideration to their tsunami hazard exposure, location, infrastructure, availability of data, and willingness to incorporate the results in a comprehensive mitigation plan. The maps incorporate the best tsunami science available at the time of publication.

PUBLISHED REPORTSMAPPING UNDERWAY

IN PUBLICATION

  • Adak and Atka

IN REVIEW

  • Kodiak Region

IN PREPARATION

  • Anchor Point, Port Graham and Nanwalek
  • False Pass and Perryville
  • Haines
  • Homer
  • Port Alexander, Craig and Ketchikan
  • Seldovia
  • Shemya
  • Skagway

 

Click to enter interactive tsunami inundation mapping interface

Pedestrian Travel Time Maps

For communities that have well-defined tsunami scenarios, it is possible to estimate the amount of time required to evacuate to high ground. These models assume evacuation by foot and include complications such as ground cover, steep terrain, and other barriers identified by the community. The full methodology is described in this overview white paper.

Tsunami News

Alaska's most recent deadly tsunami struck without warning on November 3, 1994. Witnesses described new steel sheet piles snapping in half as the railway dock, which was being refurbished, suddenly slid away from the shore. One man working under the dock somehow scrambled to safety. Another, Paul Wallin of Homer, was trapped underneath it and then killed by a speeding wall of water and debris.

The undersea landslide was about 600 feet wide, at least 50 feet deep, and composed of anywhere from 1 to 3 million cubic yards of earth. It displaced enough water to generate 20-foot waves that heavily damaged Skagway's ferry terminal and clogged the small boat harbor with debris. Eight hundred feet of the railroad dock had disappeared. 

When we think about tsunamis, most often we imagine a large earthquake moving the seafloor vertically and generating huge, fast-moving waves that can threaten communities hundreds and even thousands of miles away. These are called tectonic tsunamis, and they are a major threat to coastal communities in Alaska. However, landslide-generated tsunamis can be even more dangerous to communities near where they occur.