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(回答先: 11/04 13:17 アラスカでＭ７・９の地震 高速道路に亀裂、津波無し 投稿者 倉田佳典 日時 2002 年 11 月 04 日 21:18:55)
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Major earthquake shakes Alaska
http://www.cnn.com/2002/US/11/04/earthquake.alaska/index.html
Major earthquake shakes Alaska
Monday, November 4, 2002 Posted: 4:01 AM EST (0901 GMT)
A powerful temblor caused a crack in the Parks Highway near Healy, Alaska.
FAIRBANKS, Alaska (CNN) -- A major earthquake struck 75 miles south of Fairbanks, cracking roads, crumbling support mechanisms for the trans-Alaska pipeline and triggering mudslides, but there were no immediate reports of injuries, officials said Sunday.
The U.S. Geological Survey estimated the quake's preliminary magnitude at 7.9.
"We have heard of items being knocked off shelves," geophysicist Dale Grant said.
The earthquake struck at 1:12 p.m. (5:12 p.m. ET) and was felt throughout the state, the Alaska Earthquake Information Center reported. It was centered 45 miles east-northeast of Cantwell in the state's remote interior.
Loretta Herman, a dispatcher for the Cantwell Fire Department, said there were no reports of injuries there.
The town is located near Mount McKinley, North America's highest peak. The area is not heavily populated, and there are rarely tourists this time of year.
Officials shut down the trans-Alaska oil pipeline to check for leaks, but there were no reports of any.
"There are no ruptures or damage to the pipeline, but we did suffer some damage to the pipeline support mechanism," said Mike Heatwole, a spokesman for Alyeska Pipeline Service Company -- operators of the pipeline system.
He said the pipeline, in the area where the earthquake struck, was designed to sustain a magnitude 8.5 quake.
According to Heatwole, there are eight locations with damage to the support mechanism that holds the pipeline. In some cases, the pipeline dangles above the frozen Alaskan soil without support, he said.
Heatwole said structural engineers are being mobilized and will be deployed Monday morning to begin analysis of the damage. As an interim move, wooden structures will be built to support the pipeline.
According to the company's Web site: "The 48-inch diameter steel pipeline runs 800 miles (from Prudhoe Bay to the port of Valdez, the northernmost ice-free port in the United States) and crosses three mountain ranges and over 800 rivers or streams."
The two major north-south highways in Alaska were shut down in places because of large cracks caused by the quake, he said.
On the Richardson Highway, which runs between Fairbanks and Valdez, there was a break that is two feet wide and five feet deep, he said. Other cracks were between two and six inches wide and as deep as eight feet.
A three-foot break shut down one lane of the Parks Highway, the main route between Fairbanks and Anchorage, Wilkinson said.
He said the cracks did not cause too many headaches: "We don't have major traffic in Alaska."
The quake was a shallow one, centered about 3 miles below the earth's surface, the Alaska Earthquake Information Center reported.
The quake caused cracks in roads up to five feet deep.
"The more shallow they are, the more severe the quake is felt," Grant said.
A state trooper dispatcher in Fairbanks told CNN the quake cracked highway surfaces and triggered an undetermined number of mudslides, but there were no reports of injuries.
Bill Smith, who works at Totem Inn Cafe in Healy, a town of 1,000 people, said the temblor broke several dishes and lasted several minutes -- "about five minutes, four minutes, with the aftershocks," he said.
Smith said he had heard of no injuries, but there was some damage. "At my house, I lost the hot water heater," he said.
The owner of Denali Suites in Healy also described things falling off the shelves, and said it lasted several minutes.
"It was pretty rolly, and it was long. It was a long one," said Judy Hundrup.
She said the area experienced minor earthshaking earlier in the day, leading her to wonder whether a bigger quake was coming.
The oil pipeline traverses the Denali fault, along which Sunday's earthquake happened, said Kerry Sieh, a geology professor at the California Institute of Technology. Engineers therefore built the pipeline in a "zig-zag" pattern across the fault so that, in the event of a large fault movement, the pipeline "would undo like an accordion, rather than break," Sieh said.
"If nothing ruptured, then that's really good news for the engineers who were trying to make it in fact so that it wouldn't," Sieh said.
In 1964, an earthquake with a magnitude of at least 8.4 struck in Prince William Sound, about 75 miles east of Anchorage. The quake caused 115 deaths, with 106 due to the resulting tsunamis.
It was the largest earthquake in North America and the second largest ever recorded, according to the West Coast and Alaska Tsunami Warning Center.
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