After the January 22 earthquake and tsunami evacuation event, and as the anniversary of the 1964 Great Alaskan Earthquake approaches, it’s timely to review the updated tsunami inundation maps available at the Alaska Earthquake Center.
I excerpted sections of that map and added labels for clarity.
The following information was summarized from the “Tsunami Inundation Maps of Seward and Northern Resurrection Bay, Alaska by E.N. Suleimann, D.J. Nicolsky, D.A. West, et al, 2010. Note that it’s not the distant tsunamis that are Seward’s greatest threat, but the local tsunamis generated by underwater landslides. Locals and visitors alike must be informed of the imminent dangers and know where the tsunami evacuation safety zones are all around the bay.
Landslide Tsunami Hazard in Resurrection Bay
Resurrection Bay is a deep glacial fjord, typical of many in southcentral and southeastern Alaska. This region has a long recorded history of tsunami waves generated by landslides, including underwater landslides, avalanches, and rockfalls. In the 1964 Great Alaska Earthquake, a significant amount of the damage in Resurrection Bay was caused by locally generated tsunamis from multiple, massive underwater landslides.
In the majority of cases, distant tsunamis from the open ocean are relatively small and cause little damage. The 1964 tsunami from Prince William Sound was an exception.
Streams draining into Resurrection Bay, such as Resurrection River, Lowell Creek, Spruce Creek, and Fourth of July Creek deposit huge loads of sediment underwater on unstable, steep slopes. Earthquakes, extreme low tides, and even construction activities may trigger future underwater slides and locally generated tsunamis.
If you feel an earthquake or notice the sea level rise or fall suddenly, you must seek high ground immediately. A local, landslide-generated tsunami is imminent and there is no time for official alerts. Evacuate to high ground!
I hope this information is helpful.