New Maps, App Prepare Hawaii for Extreme Tsunami
Tsunami have crossed the ocean and hit Hawaii many times in the last century: in 1946, 1952, 1957, 1960, and 1964. But it was the Japan tsunami in 2011 that shook local emergency planners to the core. Not because of what happened to the state, but because of what could have happened.
“Japan is one of the best prepared countries in the world when it comes to tsunami, however they prepared for a 100-year event,” he continued. “All of their sea walls, evacuation zones, and procedures were based on what they knew had happened in the past, but the 2011 earthquake and tsunami was much greater than what had happened in the past.”
The need to be prepared for an unusually large tsunami intensified when Hawaii researchers discovered evidence of a Great Aleutian Tsunami on Kauai, which they estimated slammed the islands with a 30-foot high wall of water sometime between 1425 and 1665.
“The scientific and geological information suggested that it was a massive 9.0 earthquake that occurred in the Eastern Aleutian trench… the earthquake generated tsunami that far exceeded the inundations that we knew at least up until the 2010 timeframe,” explained Mel Kaku, director of Honolulu’s Department of Emergency Management. “We felt very strongly that we needed to look at this particular catastrophic scenario.”
Work began in earnest in 2013, when the state Hawaii Emergency Management Agency (formerly State Civil Defense) commissioned a study by the University of Hawaii’s Sea Grant college program. The study explored Hawaii’s exposure to similar “extreme tsunami,” modeling potential areas of inundation further inland than previous maps. The city then picked up the project.
“The city, in conjunction with our many partners, developed a new set of Oahu maps called the Extreme Tsunami Evacuation Zone maps,” Kaku said. “We also looked at refuge areas and evacuation routes to complement the current tsunami evacuation maps.”
“One critical thing that I want to emphasize is that this particular scenario does not replace the current standard tsunami evacuaton maps,” Kaku said. “We’ve added a second tsunami evacuation zone to reflect the potential for a magnitude 9-plus earthquake and resulting tsunami.”
“This particular extreme event is low probability, but has a potential for very high impact,” he added.
With new maps released for O’ahu, I was curious whether there would be updated maps for the other islands.
“XTEZ will eventually be statewide — the conversion process takes a while, gathering stakeholders and going block-by-block around the island,” DEM deputy director Peter Hirai told me in an email. “Professor Kwok Fai Cheung is working on all the other counties; some are already converting his inundation data to evacuation maps.”
“This is a Statewide effort,”confirmed Matthew Gonser of UH Sea Grant. “The other counties are in the preliminary stages of their respective processes… each county has its own methodology/procedures to then create the evacuation zone (typically smoothed out to some known/recognizable land feature, elevation, or road).”
The app gives users real-time local weather and public health alerts, maps of shelters and the tsunami evacuation zone (the XTEZ update is still pending), a customizable checklist of emergency supplies, information on what to do during different types of emergencies, and a history of major Hawaii disasters.
Based on the award-winning Ready Georgia app, the Ready Hawaii app was built by UpTop, formerly Peak Systems, creators of popular apps like Diptic. Development cost about $40,000, funded by a grant from the Coastal Storms Program of the National Oceanic and Atmospheric Administration.
NOAA also funded the research behind the XTEZ maps to the tune of about $200,000.
“The process that the city and county used, and the process that we’ve gone through with all of our partners, really highlights the cooperation and the coordination between science, the government, and the public in order to take this research — which often times just gets left on the shelf — and actually turn it into good public policy,” Mayne said.
“I believe as mayor the number one job, bar none, is assuring public safety in times of emergency, and we take this job very seriously,” said Mayor Kirk Caldwell. “I believe that the City and County of Honolulu and the State of Hawaii is about as prepared as anywhere you will find in the world for a tsunami event.”