Low funds slow
isle tsunami plan

Officials say revisions
to evacuation maps
could take 10 years

State Civil Defense officials have begun revising the tsunami evacuation maps for the first time in 15 years, but officials say the task will take at least a decade unless funding increases.

The revision began before the catastrophic seismic waves of Dec. 26, but the destruction across the Indian Ocean has given disaster planners fresh confidence in the durability of concrete structures.

That means, for instance, that the state will continue to endorse "vertical evacuation" in Waikiki, assuring residents and visitors to seek safety on and above the third floor of high-rise apartment buildings and hotels.

Brian Yanagi, Civil Defense program manager for earthquakes, tsunamis and volcanoes, said concrete or steel structures higher than six stories can withstand tsunami floodwaters because their foundation pilings tap deep into the subsoil.

"Based on what we've seen in the Indian Ocean, it looks like concrete structures did very well," said Yanagi. "You see pictures where the only thing standing is a mosque made of reinforced concrete. Everything else, made of wood, has been wiped out."

That's good news for Waikiki, said Yanagi, because evacuating the high-density resort even on a time scale of hours is simply impractical. The resulting traffic jam, he said, might leave many people stuck in cars just as the waves struck.

With $150,000 annually from the National Oceanic and Atmospheric Administration, Yanagi said Civil Defense has begun redrawing the tsunami evacuation maps that appear in the front of the Verizon white pages.

The first of the new maps, covering the North Shore of Oahu, should be ready for inclusion in the 2005 directory, he said. But unless that funding level increases, the agency will not be able to finish the entire state for "10 or 15 years," he said.

The current maps, which date to 1990, reflect the state's assessment of how far inland people must flee to be safe from waves generated by a major earthquake around the Pacific Basin.

The revisions will incorporate more detailed profiles of the submarine landscapes just offshore, which determine what form tsunami waves take when they run up on land. On the open ocean, tsunamis are small -- only a few inches high -- and travel at 500 mph, but they slow down and build up once they hit the shallows near a coastline.

As much of the stunning video from the Indian Ocean shows, tsunamis hit land more like a powerful flash flood than the classic shore break familiar to surfers.

Benefiting from sophisticated computer modeling, the new maps will also better calculate how the waves will behave inland -- including lateral movement down a coast, said UH ocean engineer Kwok Fai Cheung, who is preparing the maps on a Civil Defense contract.

"If a wave hits Diamond Head, for instance, part of the wave will run up the hill, and part of it will move down the coast," he said.

Data for the modeling comes from the dozen or so tsunamis that have hit Hawaii in recorded history, said Yanagi. Notable among them are the 1946 tsunami, generated from a 7.4-magnitude quake in the Aleutian Islands; the 1957 tsunami, generated by a quake on Alaska's Andreanof Island; and the 1960 tsunami, spawned by a quake off Chile.

But the calculations are complex because not all big quakes generate destructive waves. The huge 1964 earthquake in Alaska, for instance, sent deadly waves to the Pacific Northwest and California but not Hawaii.

Cheung said he will work with the state Department of Land and Natural Resources and the counties to turn his inundation maps into evacuation maps for the phone book.

"An inundation map shows the extent of flooding you would expect during a tsunami. For evacuation, you want to be a little more conservative, taking into account population demographics," he said.

The maps also will discount what Yanagi calls "extreme worst-case scenarios" such as waves generated by a huge submarine landslide or asteroid impact.

"The maps in the phone book reflect something more realistic -- something that is likely to happen in your lifetime," says Yanagi. "There is no way to plan for these megatsunamis. You would have to evacuate everybody to the mountains."

UH scientists Gary McMurtry and Gerard Fryer have found evidence that a megatsunami hit the Hawaiian Islands about 120,000 years ago, triggered when a chunk of the Big Island slid into the ocean. If a similar landslide occurred today, Fryer said in an interview, it would generate a wave that would wash over the isthmus of Maui -- that is, the saddle between Haleakala and West Maui, and would flood Oahu up to Wahiawa.