Tsunami research becoming a top priority

By Ashley Cobb and Elysa-Lyn Rosso

In the aftermath of Hurricane Katrina and the Indian Ocean tsunami, several University of Hawai`i researchers are devoting themselves to making Hawai`i a more tsunami-ready state.

Gerard Fryer, associate geophysicist of the Hawai`i Institute of Geophysics and Planetology, is working with members of the Tsunami Warning Center to set up broadband seismometers around the islands. Seismometers are devices that receive seismic impulses from earthquakes.

"We're putting together a scheme to analyze the data from (seismometers) and when they're installed we'll be able to get a warning out within two minutes of the initial shaking of the ground," said Fryer.

These instruments will be set up at the closest points of seismic activity, and are ultra sensitive to both slow and rapid motions of the earth. According to Fryer, the sensitivity of the instruments will be extremely useful in predicting a tsunami.

There are already two broadband seismometers within the islands. One is located near the Big Island and the other on Oahu. More seismometers will be put near Maui, Kauai, Molokai and Niihau. Fryer is hoping that the entire network of seismometers will be completed within a year.

Other University of Hawai`i researchers have developed a sophisticated computer model that can detect tsunamis and estimate their impact, warning us early of danger and potentially saving lives.

Kwock Fai Cheung, a professor and department chair of the UHM Ocean and Resources Engineering department, is the head of this tsunami warning research. His work is government-funded through the National Tsunami Hazard Mitigation Program. Cheung is working with two Tsunami Warning Centers and the NOAA Pacific Marine Environmental Laboratory to provide real-time tsunami forecasts for the Pacific basin.

"The idea is quite simple: a tsunami that is created in the Alaska region takes five hours to get to Hawai`i," Cheung said. "But the computers are slow ... it might take a couple of days just to do the calculation...so what we are doing is performing all of the calculations in advance."

The scientists generate different scenarios, and save the results in a computer database. Once a real tsunami occurs, they can search the database to best match the actual situation.  

Once the scientists detect an earthquake, time is critical. Within the first hour, the scientists receive data from underwater buoys. The calculation then takes about five minutes. "So this means we have another four hours to determine whether the tsunami coming to Hawai`i is destructive or not," Cheung said. Next, they determine whether or not to call for an evacuation, which requires three hours to do in coastal areas.

The second component of Cheung's research is to update Hawaii's tsunami inundation map, which shows the extent of flooding in the event of a tsunami. Hawai`i State Civil Defense will use Cheung's results to update the evacuation maps currently printed in phone books.          

The current evacuation maps have not been updated since 1991, and could be underestimating the amount of damage in some parts of the island, Cheung said. "The evacuation map that we are using right now is based on a one-dimensional model," he explained.

This model assumes the tsunami always travels in one direction, and does not take into account ocean-floor topography. For example, the shape of the ocean floor in Hilo Bay contributes to destructive tsunami waves. There are steep cliffs on either side of the bay and a flat coastal plain in the middle, forcing the water inland. "The shape of it funnels the energy," Cheung said. "The water has nowhere else to go." Cheung is using a more realistic two-dimensional model to update the maps.       

According to Hawaii's State Civil Defense, tsunamis are our state's number one natural disaster killer. Officials and scientists alike have said it's not a matter of "if" but "when" the next one will strike. "People always say we are overdue for a tsunami, because there were five major tsunamis during the past 100 years," Cheung said. "We haven't had one for 40 years. And so, some people would say because of that, a tsunami might be coming anytime."

"The risk of tsunamis is a lot higher than hurricanes, based on the historical records," Cheung continued. The immediacy of tsunamis also increases their danger. "With a hurricane, we can watch it on TV for several days," he said. "Tsunamis are more dangerous in that you don't have a lot of time to prepare."

Fryer said that one of the biggest challenges and dangers comes from evacuation. "When people panic they get hurt," Fryer said. "That's why all planning has to be done ahead of time, so all the cognitive work is complete and there is little margin for error."

The north shores of the islands are most at risk, Cheung said, because tsunamis generated in Alaska and Japan would arrive relatively quickly. The south shores are at risk from tsunamis generated in Chile, which travel further and therefore allow for more preparation time.

A locally generated tsunami, although rare, could be very destructive. "If a tsunami generates on the Big Island, it takes half an hour to get to Oahu," Cheung said. "You don't have time to evacuate." He added that such a tsunami could hit the Big Island in a matter of minutes. He said, "People on the Big Island are told that if you feel an intense earthquake, and if you are near the coastline, just get away."

The tsunami project may take up to 10 years to complete, and Cheung attributes this to timing of his project, which began in 1998. "At that time, people didn't seem to be interested in tsunamis. There was no urgency," he said. "But then after the Indian Ocean tsunami, it became a higher priority item."

Yong Wei, an Ocean and Resources Engineering graduate student working for Cheung, said that after last year's tsunami, his team's research budget increased about threefold. "Since last year's tsunami, our research has been receiving more and more attention from the public," Wei said. "More importantly, people are starting to realize how important tsunami research is in the sense of saving lives and properties," Wei said. "Our work is saving people."

"A tsunami, or 'harbor wave' in Japanese, is a series of waves usually caused by underwater earthquakes and occasionally by underwater volcanic eruptions and landslides. Sometimes incorrectly referred to as tidal waves, tsunamis can either be generated by a distant earthquake that occurs anywhere in the Pacific Rim, or local earthquakes that happen just offshore." -Coastal Services, September/October 2004.