New scientific paper maps out Juneau’s worst-case scenario for localized tsunamis

A new scientific paper models worst-case scenarios for tsunami events in Juneau.

Juneau Emergency Programs Manager Tom Mattice is particularly interested in the maps showing areas that may flood after a possible underwater landslide triggers a tsunami.

“We’ve always recognized that there is some risk of a localized tsunami,” he said. “We always knew that Skagway had had them, and they had occurred in other places. Nobody had ever been able to define the risk of an underground, or even above ground tsunami like a Lituya Bay, for example. Nobody had ever defined that risk for Juneau. … This now gives us a line on the map to understand if they’re in a compromised area or not.”

The scientific paper and maps were published by the Alaska Division of Geological and Geophysical Surveys.

Mattice said Juneau doesn’t have a tsunami warning system, because the risk is low. However, he shared some rules  of thumb for people in the newly mapped inshore tsunami flood zones.

“If an earthquake is big enough to knock you down, then you should consider going to higher ground. If an earthquake is longer than 20 seconds or more, it’s estimated to be greater than a 6.0, and if you live in an area that you feel is compromised, you should seek higher ground,” he said. “If you live inside of the inshore inundation tsunami map zone and there is an earthquake and you fear for your safety, you should immediately seek higher ground. If nothing occurs in 30 minutes, nothing’s gonna to happen. Go home, have a great day.”

Mattice said he doesn’t expect the paper to affect flood insurance rates because, while the consequences of a these worst-case scenarios are high, the probability of these is low.

Mattice will be on “A Juneau Afternoon” on KTOO next Tuesday with more information.

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