Some confused about boundaries for ‘extreme tsunami’ zones

Some confused about boundaries for 'extreme tsunami" zones
Updated: May. 8, 2017 at 5:12 PM HST
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HONOLULU (HawaiiNewsNow) - When a tsunami watch like Thursday's is issued, people living in the inundation zones like Waikiki are expected to pay attention.

But in cases of extreme tsunamis, many people don't realized that the city recently expanded the Waikiki tsunami zone all the way to Moiliili and parts of Kapahulu.

"No, I was totally unaware. I thought that as long as I was off Waikiki that we were kind of in the clear," said Mikum Leah Webster, of Waikiki.

Added Ellen Hynson, also of Waikiki: "My family and I have a plan where we would meet. But now that place is in the zone."

Since 2010, the city has considered the area mauka of the Ala Wai canal as the mauka boundary for Waikiki evacuation zone.

But new data suggest that over the past 30,000 years, tsunami's triggered by rare and massive earthquakes have caused damage further inland.

"What it did create is a separate set of maps that indicated a larger area that would have been inundated in this extreme tsunami scenario," said Mel Kaku, director of the city Department of Emergency Management.

Extreme tsunami are a 1-in-1,000-year scenario and could be triggered by earthquakes with a magnitude of 9.0 or more.

The city expects people to follow the 2010 zones for typical tsunamis. The public would be alerted if they should follow the extreme zone, a call that would affect thousands more people.

"For the 2010 scenario, roughly 85,000 people. When we look at an extreme tsunami scenario, now we're thinking closer to 300,000 folks," Kaku said.

Some would like the city to post street signs to mark the extreme tsunami zones.

"That would be intuitive. To have signs located along the way to have as a guide when your out of the zone," said Webster.

The city says such warning signs are in the works. It recently received a federal grant to pay for them.

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