Tsunami safety rules
• An earthquake felt in a low-lying coastal area is a warning of possible, immediate danger. Move to higher ground away from the coast.
• A tsunami is not a single wave, but a series of waves. Stay out of
danger until an “all clear” is issued by a competent authority.
• Homes in low-lying coastal areas
are not safe. Don’t stay in such buildings if there is a tsunami warning.
• The upper floors of high, multi-story, reinforced concrete hotels can
provide refuge.
Source: wcatwc.arh.noaa.gov
After seeing and hearing newscasts about the terrible devastation in northern Japan since the Pacific island nation was rocked by an earthquake and submerged by a tsunami last Friday, many people here on the coast have asked, “Can it happen to us?”
One Skidaway Institute of Oceanography marine geologist’s reply to this question was that it is possible, but not likely.
“Our history here isn’t one that suggests we’re in much danger of a tsunami,” Dr. Clark Alexander said. Alexander is the director for Georgia Southern University’s Applied Coastal Research Laboratory at Skidaway.
Still, county officials aren’t taking chances. Liberty County is rated a “tsunami-ready county.”
Liberty County EMA Director Mike Hodges said preparing for tidal waves is part of the county’s general evacuation plan.
“It’s the same evacuation routes as for a hurricane,” Hodges said. “Liberty County has an east-to-west evacuation.”
Residents would head west inland and to higher ground, along state highways 84 and 196, which would be “opened up” for evacuees by local law enforcement, he said.
“You’d get out of the way of the water completely,” Hodges said. “(Tsunamis) are a tremendous force.”
Alexander said he has past experience with earthquakes and tsunamis. The California native did his undergraduate work at Humboldt State University, just south of Crescent City, Calif., where the recent tsunami brushed the continental U.S. after having put Hawaii on alert and into evacuation mode. Crescent City’s harbor was heavily damaged and several people were swept out to sea after 8-foot waves pummeled the port town.
Alexander said there is no history, no deposits associated with tidal waves found to support the occurrence of tsunamis along the east coast. There is evidence, however, of earthquakes occurring in the southeast.
Alexander said nearby Charleston, S.C., experienced a large earthquake in 1886.
“We have about 375 years before we need to worry about (another earthquake there) too much,” he said.
“It’s a slip fault,” Hodges said. “It wouldn’t be as devastating tsunami-wise.”
Since the epicenter for the South Carolina quake was located under what is now Orangeburg, which is a land-based fault line, it would not create a tsunami, Alexander explained.
“The Charleston quake was maybe 7.3 to 7.5 on the Richter scale,” he said. “It would be similar (in magnitude) to earthquakes in the 1990s in California.”
Alexander suggested the southeast address strengthening buildings for earthquakes and implement stricter building codes like in Japan. The marine geologist said most of the recent Japanese victims were swept away by the tsunami and that the earthquake alone did not kill or injure as many people as did the tidal wave.
“Most of the loss of life in Japan wasn’t from the earthquake; it was from the tsunami,” he said. “Their building codes are accommodating the kind of energy they’d experience.”
Alexander said man has not yet found a way to “engineer your way out of a wall of water.”
He explained that Japan is in an area where there are tectonic plates shifting under the ocean. The island nation is located in the Pacific ring of fire, Alexander said.
“When they (plates) move, they move quickly and release a lot of energy (into the Pacific),” he said.
The Atlantic ocean basin is different; it has a passive spreading center, Alexander said.
“Japan is very aware of its geologic setting … they have an early warning system they set up in the last seven years or so,” Alexander said. “It measures the ‘p’ waves, which are direct waves from the initial event. It’s enough to start the sirens and get people moving before the ‘s’ waves come. These are the waves that start shaking the earth. Even a minute may be enough to start saving lives.”
“There’s been more earthquakes and volcanic activity than there’s ever been,” Hodges said. He said residents need to take evacuation warnings seriously, whether a tsunami or hurricane is expected.
“We go through this every hurricane season,” the EMA director said. “Some people don’t believe it will happen. They have a right to stay if they want to do that. But it comes to a point when it is no longer safe to assist them. Once we reach that point, they’re on their own.”
EMA Deputy director Larry Logan suggested local residents invest about $25 in a NOAA weather radio.
“Getting information out to people is key,” he said. “People should have their evacuation plans ready and not wait for hurricane season.”
Hurricane season officially begins June 1.
