Home Natural Hazard Management Hawai’i tsunami zone maps may be flawed

Hawai’i tsunami zone maps may be flawed

Hawai’i’s tsunami evacuation maps haven’t been updated in 13 years and may be inaccurate since they’re based on an outdated computer model, several experts said recently.

And it will take five to 10 years before the statewide maps will be completely revised to reflect the effect of tsunamis emanating not only from the Pacific Rim but also from elsewhere around the globe and from waters off the Big Island.

“Some of the maps might not be that accurate,” said Kwok Fai Cheung, chairman of the Ocean and Resources Engineering Department at the University of Hawai’i-Manoa, who was hired by the state last year to update the maps.

The effects of tsunami generated by local events — earthquakes or undersea landslides — may be significantly under-estimated by the existing maps, he said.

Even though a local tsunami “is not as frequent … if it happens, the effect would be quite disastrous,” he said.

The evacuation maps, found in the front of Hawai’i telephone books, were first published in 1991 and have not been updated since. While Cheung started working on his project a year ago, the recent Indian Ocean disaster has raised interest in detection and preventive measures in tsunami-prone states, such as Hawai’i.

The existing maps are one-dimensional, in the sense that they do not take into account the effects of ocean-floor topography that can change the way a wave behaves as it approaches the shoreline.