Hawaii Civil Defense is advising all residents in tsunami inundation zones to evacuate immediately.
The alert, issued at 10:38 p.m., reads: "Leave all coastal evacuation zones immediately. Refer to Hawaiian Telcom or Paradise Pages for evacuation maps."
The earliest that hazardous waves could hit Kauai is 3:07 a.m., said civil defense. Oahu could be hit by 3:14 a.m.
A tsunami warning was issued at 9:30 p.m. for Hawaii as a result of a 8.9-magnitude earthquake near the east coast of Honshu, Japan.
The Pacific Tsunami Warning Center issued a tsunami watch at 7:56 p.m. after the quake struck 231 miles northeast of Tokyo.
HAWAII TSUNAMI EVACUATION ZONES
"A tsunami has been generated that could cause damage along coastlines of all islands in the state of Hawaii," the agency said. "Urgent action should be taken to protect lives and property."
The warning center said wave heights cannot be predicted, but the first wave may not be the largest.
Chip McCreary, director of the warning center, said the latest forecast models show "wave amplitudes of up to 2 meters (6 feet) beyond normal sea levels in Hawaii.
"What these waves look like is an elevation of sea level, where the sea level will rise above its normal level and stay high for 10 or 15 minutes before they recede," McCreary said, explaining the difference between tsunami and regular waves.
Because of the long length of tsunami waves, "they wrap around our islands very efficiently" so there is no point of impact that may see higher waves than other areas.
"There are some places that will be affected more than other places," McCreary said. "From our history, we’ve had bigger impacts in Hilo, Kahului and Haleiwa and our models bear that out."
Geologists and geophysicists at the center are using observations from coastal gauges in Japan as well as deep ocean gauges deployed since the 2004 Indian Ocean earthquake, he said.
The center may be able to get a better fix on the size and time when the waves hit coastal gauges at Midway Island about 12:30 a.m., McCreary said.
John Cummings, a spokesman for city Department of Emergency Management, said about 30,000 residents live in the coastal inundation zone, according to recent estimates.
He said anyone in an evacuation zone should leave and either go to a friend’s or family member’s home. Residents can even walk about five minutes out of an evacuation zone.
He asked people not in evacuation zones to "stay off the roads."
Refuge centers are being opened where people can get water and use the restroom. Emergency shelters will be opened after the tsunami hits if needed, he said.
Mayor Peter Carlisle had several announcements, including asking residents to conserve water because depletion of the system could hinder efforts of firefighters if needed later on.
He also asked residents to call 911 only for life-threatening emergencies because phone lines are being overwhelmed, and to use cell phones only for planning an evacuation. He asked residents to stay off the roads and not go to stores or gas stations because lines are causing gridlock and impairing the evacuation.
He asked residents to follow the directions of first responders and asked visitors to heed the advice of hotel staff members.
"Visitors, please follow directions of hotel staff," he said. "Do not go out and do things on your own. Follow the instructions of these people. Those of us in Hawaii are aware of this type of problem. We follow their directions, you should, too."
Even before civil defense sirens sounded just before 10 p.m., people were lining up to get gas around Oahu. Police dispatch reported arguing over gas in Ewa Beach and lines to get gas on Fort Weaver Road.
About an hour after the quake struck, Jake Chang, of Papakolea, was at the Aloha gas station on Vineyard Boulevard filling up his truck and a plastic gas container to power his generator.
"I was watching TV," he said. "I saw the footage of Japan. It was unreal."
In the first three hours after the quake, there were 23 significant aftershocks ranging from 5.4 to 7.1 in magnitude, according to the U.S. Geological Survey.
"The trough of a tsunami wave may temporarily expose the seafloor, but the area will quickly flood again," the warning center said. "Extremely strong and unusual nearshore currents can accompany a tsunami. Debris picked up and carried by a tsunami amplifies its destructive powerr. Simultaneous high tides or high surf can significantly increase the tsunami hazard."
Hawaiian Electric has opened its emergency command center and is implementing its tsunami plans, according to Peter Rosegg, Hawaiian Electric spokesman.
The striking IBEW union workers are still out, Rosegg said, adding that the electric company has an agreement with the union that workers will return to work in case of a "major emergency."
"We have an agreement, but until we know the extent of the emergency we will not know what we need," Rosegg said.
Meanwhile, HECO is moving its emergency vehicles to higher ground and Rosegg said it is shifting generation to facilities that are the least threatened by a tsunami.
"We are prepared with nonunion and management crews," Rosegg said.
About 1,300 IBEW members went on strike Friday.
In 1854, an earthquake measuring 8.4 on the Richter scale devastated the region from Tokai to Kyushu and killed an estimated 10,000 people. In 1896, an 8.5-magnitude earthquake hit the Sanriku coast; the earthquake and the resulting tsunami killed some 27,000 people.
Tsunami waves were reportedly observed in Hawaii and California, but no significant damage was reported.
And in 1946, an 8.1-magnitude quake hit Nankaido, killing 1,362.
Over the last century, tsunami have killed hundreds of people and caused millions of dollars of damage in Hawaii. The worst took place in 1946 when a 7.1-magnitude earthquake in the Aleutian Islands resulted in a tsunami that flooded downtown Hilo, killing 159 people. Hilo was hit again in 1960 when an 8.3-magnitude quake in Chile generated waves of up to 35 feet that destroyed buildings and caused 61 deaths.
The last significant tsunami in Hawaii occurred in 1975 when an earthquake off the Big Island generated a 26-foot wave that killed two people and injured several others.