Japanese, who spent $2 billion last year and are Hawaii's No. 2 tourist group after Americans, will likely cut back travel significantly, Abercrombie said.
"The economic consequences will be severe for us," said Abercrombie, who was elected in November after serving 20 years in Congress. "It's going to be terrible. It's something we have to come to grips with."
The state -- which suffered tens of millions of dollars in damage from the tsunami spawned by Friday's magnitude-9 earthquake off Japan -- has already logged several thousand tour and hotel cancellations from the Japanese market, the Honolulu Star-Advertiser reported.
"This is just the first shock wave," Hawaii Tourism Authority Marketing Director David Uchiyama said.
A "cultural sense of obligation and responsibility" tends to keep Japanese people from traveling during crises, he told USA Today.
Tourism Authority Chief Executive Officer Mike McCartney told MSNBC the crisis came just as Hawaii was rebounding from two bad years.
"The recession hit Hawaii pretty hard," he said. "We lost two airlines, ATA and Aloha. Two cruise ships. We had the financial meltdown across the country, and we had H1N1."
Major tourist airlines ATA Airlines and Aloha Airlines shut down in 2008. An H1N1 swine flu strain caused a worldwide pandemic in 2009 that killed some 17,000 people and was declared over last August.
The U.S. Environmental Protection Agency said Tuesday it would add radiation monitors in Hawaii, other Pacific islands and the Western United States.
The U.S. Nuclear Regulatory Commission said Hawaii was not expected to experience harmful levels of radioactivity.