When a giant earthquake near the Aleutian Islands in Alaska triggered a tsunami on April 1, 1946, Hawaiʻi was woefully unprepared.
In less than five hours, a massive wave crossed the Pacific and hit the Hawaiian Islands.
"We had no tsunami warning system, and so 158 people statewide perished," said Laura Kong, the director of NOAA's International Tsunami Information Center.
Not wanting history to repeat itself, officials developed the first Pacific-wide tsunami warning system. By the 1990s, the state had released its first evacuation maps, said Kong.
But two disasters in the early 2000s prompted officials to ask if those plans were sufficient.
The first was the Boxing Day Tsunami in 2004, which killed over 220,000 people across 14 different countries near the Indian Ocean. It was one of the deadliest natural disasters in recorded history.
In 2011, Japan experienced one of the largest earthquakes in its history. It generated a tsunami that killed thousands of people and destroyed several towns.
Laura Kong said disasters of that scale happen rarely, once in every couple of thousands of years. Still, Hawaiʻi's number could come up anytime.
Scientists and state officials teamed up to revamp the state's evacuation zones to account for the worst-case scenario: a tsunami generated by a magnitude 9.0 or greater earthquake near the Aleutian Islands, the same place where an earthquake set off a tsunami in 1946.
Kwok Fai Cheung, a researcher with the University of Hawaiʻi at Mānoa's School of Ocean and Earth Science and Technology, developed a computer model of how such a tsunami would impact Hawaiʻi.
That research helped the counties of Honolulu, Kauaʻi and Maui release new maps that reflect who should evacuate if Hawaiʻi experiences a one-in-a-thousand tsunami.
But Cheung said even those maps might be outdated in 10 to 15 years.
Scientists now have to contend with future threats, as well as past disasters, to understand Hawaiʻi’s vulnerability to tsunamis. One of the top concerns is how sea levels will rise over the next century.
"The sea level increase would exacerbate the impact of a tsunami. For the tsunami evacuation maps that we developed earlier, the scenarios are based on the past sea level," said Cheung. "We need to constantly update the evacuation maps to reflect the latest scientific information."
Certain agencies have already started to incorporate sea level rise into this type of disaster planning. Cheung said he has worked with the state Department of Transportation to build sea level rise into their tsunami modeling and preparation in their 2050 Honolulu Harbor Master Plan.
Overall, Cheung said that while the state's response has evolved a lot since the first warning system was put in place almost 80 years ago, it's still a work in progress.
"I think I would give Hawai’i a passing grade," Cheung said. "But there's still a lot that we don't know."
