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City emergency officials joined Honolulu Mayor Kirk Caldwell on Thursday to unveil broadened tsunami evacuation maps for the island, which now include large inland swaths of Oahu vulnerable to rare, extremely strong tsunamis.
The officials also debuted a new downloadable disaster-preparedness mobile app customized for the island.
SEEK HIGHER GROUND
If you feel an earthquake, emergency officials say to seek higher ground immediately — don’t wait for an official warning. Go on foot, don’t pack belongings, and wait for the “all clear” to return.
SAFE ZONE (GREEN)
These are the parts of the island that emergency officials have deemed safe from a tsunami strike.
EXTREME TSUNAMI EVACUATION ZONE (YELLOW)
People in these more inland areas should evacuate in an extreme tsunami warning, along with those in the regular zones closer to shore.
TSUNAMI EVACUATION ZONE (RED)
People in these low-lying areas should evacuate to higher ground or designated refuge areas during any tsunami warning.
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The new so-called “extreme tsunami evacuation zones” typically lie farther inland, according to new maps provided by the city Department of Emergency Management.
If an especially strong earthquake threatens Oahu with a tsunami, people in these extreme zones, which are shaded in yellow on official maps, would be alerted to evacuate along with those in the regular zones closer to the ocean.
That would likely involve a magnitude-9 earthquake or stronger, striking at a shallow-enough depth, said DEM Deputy Director Peter Hirai.
Some 90,000 people live in the regular evacuation zones, while another 330,000 people live in the extreme zones, he added. The University of Hawaii at Manoa’s Tsunami Inundation Mapping project helped put the new models together, according to a DEM flier.
The updated maps have been posted at the department’s webpage, at honolulu.gov/dem.html
The app, dubbed “ReadyHawaii,” allows families to put together a disaster plan, arrange a shared meeting place, get local emergency contacts and peruse maps to find shelters, along with tsunami evacuation zones and “refuge areas” that have been deemed safe to get to in such an event.
The app’s maps don’t yet include the extreme evacuation zones, but they’re expected to be added in the next couple of weeks or so, DEM officials said.
ReadyHawaii is free to download. It’s an information resource designed to help Oahu residents and families plan in advance, but not as an alert service during a real-time disaster. For such alerts, residents can set up a free account at Nixle.com
At Thursday’s briefing, officials with the Pacific Tsunami Warning Center said Hawaii remains especially vulnerable to tsunamis generated by any large quakes in the Aleutian Islands.
“There a larger fraction of the energy comes right at us,” said Gerard Fryer, a senior geophysicist with the warning center. Aleutian-based earthquakes in the high 8.0-magnitude range could cause flooding in Oahu’s newly designated extreme tsunami zones, Fryer said.
The 1946 tsunami, which killed 159 people in Hawaii, was generated by a magnitude-8.1 quake in the Aleutians.
If the quake centers in other regions, it would likely have to be at least 9.0 in magnitude for a tsunami to reach Oahu’s extreme regions, he added.
“We’re still working out these things, running the models,” Fryer said.
Pacific Tsunami Warning Center officials would need about 25 minutes to decide whether a tsunami triggers an “extreme” designation — but if the quake was in the Aleutians, that would still leave them about four hours to evacuate people before such a tsunami would hit Hawaii, Fryer said.
“The isolation of Hawaii saves us in this event,” he said. There’s nothing that indicates that the islands are overdue for such an extreme tsunami, Fryer added.
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