KANE'OHE — State and city officials are trying to determine the source of an earthquake and tsunami hoax on Sunday that sent hundreds of people to higher ground and tied up emergency communication lines for hours.

Civil defense, police, Pacific Tsunami Warning Center and media were inundated Sunday with more than 800 calls from people trying to verify rumors that predicted a Big Island earthquake that would cause a major tsunami, supposedly due to hit the Islands Sunday night.

Officials scrambled to squelch the rumor, but it persisted for hours as people rushed to fill gasoline tanks, purchased emergency supplies and sought refuge. At this point, the best evidence points to an e-mail that may have originated in Australia.

The hoax caused rescheduling of an emergency siren test in Waimanalo slated for yesterday morning.

Civil defense hopes an investigation will reveal the source of the rumor, to prevent it from happening again, and is looking into several possibilities, including the e-mail out of Australia.

Information about the e-mail has been turned over to the state attorney general, who said his office is conducting a fact-finding study to see if criminal activity was involved.

A Nov. 4 report on The Age, an Australian news Web site, said the Australian attorney general was investigating a hoax e-mail claiming to be from the Pacific Tsunami Warning Center in Hawai'i, warning of an impending tsunami bound for Japan, said John Cummings III, O'ahu Civil Defense spokesman.

"We were reasoning that somehow that e-mail may have floated around again, popped up on the Big Island and started everything off," Cummings said.

Dave Curtis, of state Civil Defense, said the Australian e-mail is one piece in the puzzle, and other possibilities are under scrutiny.

"I can't help thinking it had to be some entity that people believed, like a radio station or television station," Curtis said. "But we don't have any indication that any radio station or any television station put out anything of that nature."

People became argumentative when Civil Defense operators told them there was no earthquake or tsunami, Curtis said.

The hoax tied up communication lines, leaving real emergencies at risk of being neglected, Curtis said.

"We're looking into several different sources to see if maybe we can figure out where this thing might have started, which will help us in the future to figure out how to stop these things if they get stated again," Curtis said.

O'ahu Civil Defense has determined neither its officials nor the police initiated the warning, said Bill Balfour, administrator for O'ahu Civil Defense. Claims that federal firefighters issued the warning also are unfounded, Balfour said.

"We're trying to follow up leads, but it's pretty much a needle in a haystack," Balfour said. He added that his office will not be "beating the bush" for an explanation, nor has it been asked to find answers.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.