Tsumani Preparedness Update

The likelihood of an “extreme” tsunami hitting Hawaii is slim, but city officials aren’t going to take any chances. Two informational meetings will be held in December in West Oahu to update residents about revisions to tsunami evacuation zone plans.

Sponsored by the city Department of Emergency Management, the public meetings will be held from 7 to 9 p.m. Dec. 1 at Kapolei Hale and Dec. 9 at Ewa Mahiko District Park.

Hawaii’s current preparedness plan is based on the 1946 tsunami that ravaged Hilo and Kauai, killing 159 people — the deadliest tsunami in Hawaii’s recent history.

But studies are now suggesting that this plan may not be enough.

Evidence found in a sinkhole on Kauai, researched in part by Rhett Butler, a scientist at UH’s Hawaii Institute of Geophysics and Planetology, says that about 500 years ago, a massive tsunami struck Hawaii — a wave that was three times larger than the 1946 wave.

There is a 0.1 percent chance that a 9.5-magnitude earthquake in the eastern Aleutian Islands could generate a tsunami that would cause water levels to rise 26 to 30 feet above the Makauwahi sinkhole (by comparison, the 1946 tsunami raised water levels only 8 feet).

It’s a small percentage, but those are the same odds that produced Japan’s 2011 Tohoku earthquake.

The city therefore has redrawn its plan to include a second, larger evacuation zone, should this massive tsunami hit.

For more information, visit honolulu.gov/dem.