Seismographs record data at the University of Fairbanks
Posted on 11/03/2002 10:22:04 PM PST by Ernest_at_the_Beach
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The largest earthquake anywhere in the world this year has struck central Alaska. It measured 7.9 on the Richter scale. Highways were damaged but no casualties have been reported.
United States Geological Survey spokeswoman Carolyn Bell says the epicentre of the quake was 120 km (75 miles) south of Fairbanks and about 280 km (175 miles) northeast of Anchorage. It occurred just after 1 pm local time (22.00 GMT).
 I ran out to the car and it was hard to stand up. That's the first earthquake I ever felt outside. That's pretty unusual. We were a long way from the epicentre  |
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Geophysicist Paul Whitmore
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"The only damage I know of right now is serious cracks up to a foot wide and earth displacement in the Denali Park's highways," Bell says.
"It's quite large. There's going to be damage to buildings," she added. The Alaska Earthquake Information Center said the earthquake had been felt strongly throughout the state.
The quake triggered the automatic protection system on the Trans-Alaskan oil pipeline. Engineers manually shut it down a short time later. Helicopters are currently flying along it looking for any damage.
'Wake-up call'
There are preliminary reports of light damage in communities throughout central Alaska.
Paul Whitmore, a geophysicist at the West Coast Alaska Tsunami Warning Center in Palmer, Alaska, near Anchorage, said the quake "almost knocked me off my feet."
"I ran out to the car and it was hard to stand up. That's the first earthquake I ever felt outside. That's pretty unusual. We were a long way from the epicentre," he said.
"Sometimes we see that after big earthquakes the seismicity in the whole region may tick up. This is a good case for people to review their safety plans, make sure their bookcases are attached to the walls and so forth. It's really a good wake up call," he added.
The Denali fault is a major, seismically active strike-slip fault that cuts through Alaska, slicing the rugged Alaska Range of mountains and bounding the precipitous north face of Mt. McKinley, the highest peak in North America. Denali is the local name for McKinley.
Streams and glacial moraines crossing the fault have been displaced because of its movement in the past. Some geologists believe that two sides of the fault-line have slipped over 400 km (250 miles) in the past 200 million years.
Scientists have believed that this section of the Denali fault has the potential of generating earthquakes as large as magnitude class 8, but none that large have been recorded in historic time, since the beginning of the last century.
However, they add that the section of the fault near the epicentre had been thought capable of producing a major earthquake on the basis of geologic evidence and from the nearby occurrence of smaller earthquakes.
The largest earthquake ever recorded in North America was a M9.2 that occurred on another section of the Denali fault line near Prince William Sound in Alaska in 1964. 125 people were killed.
And this site is very interesting:
As I read it the aftershocks are happening!
You are incorrect.
Carolyn
ANCHORAGE, Alaska (AP) _ A violent earthquake slammed a remote area of Alaska's interior and delivered a jolt so strong that it created giant waves on lakes and ponds around the continent. The magnitude 7.9 quake was one of the strongest ever recorded in the United States.
The quake, centered on the Denali Fault 90 miles south of Fairbanks, struck Sunday at 1:13 p.m. Alaska Standard Time _ its effects strongly felt in Anchorage about 270 miles to the south. ``It shook so bad you could not stand up on the front porch,''said Jay Capps, a grocery store owner between Tok and Glennallen in the southeastern part of the state. ``It sounded like the trees were breaking roots under the ground.'' Only one minor injury was reported, but the quake did considerable damage to Alaska's infrastructure. The temblor opened 6-foot cracks in highways and roads, shook homes and damaged supports to the Trans-Alaska Pipeline.
Officials manually shut down the pipeline after the quake, and the line was still out of service Monday. The oil flow can be manually stopped for maintenance or other reasons without affecting oil deliveries. The quake created a ripple effect thousands of miles away _ from the bayous of Louisiana to lakes in the Seattle area. In the New Orleans area _ more than 3,000 miles away _ residents saw water slosh about as a result of the quake's awesome power. On Seattle's Lake Union _ more than 1,400 miles south _ waves shook some houseboats loose from their moorings and some slammed into docks.
In Mandeville, La., Carol Barcia, 47, saw boats bounce around from the deck of her house. ``One poor guy across the canal from us fell off his sail boat,'' she said. Experts say such an effect is common during powerful quakes. ``This earthquake was shallow and the energy went directly into the surface and that is what causes these effects so far away,'' said Dale Grant, a geophysicist with U.S. Geological Survey's National Earthquake Information Center in Golden, Colo.
Grant said he received calls from nuclear power facilities in various states _ including Minnesota and Washington _ that reported unusual water movement. Bruce Turner of the West Coast and Alaska Tsunami Warning Center said the earthquake did not generate a tsunami.
Numerous roads developed wide cracks, including the Alaska Highway near Northway, about 250 miles southeast of Fairbanks. The Richardson Highway, which parallels the pipeline between Valdez and Fairbanks, was closed near Paxson after gaps opened that were 2-to-6 foot wide and 5 feet deep, Wilkinson said. About 20 miles north, the ground on one side of the highway had dropped more than 2 feet.
The worst reports of damage were along a two-mile stretch of the Tok Cutoff, where numerous rock slides and hundreds of yards of 6-foot openings in the road could be seen. Fuel tanks were knocked over in Slana, a village with no electric utility; families use diesel fuel to power generators.
Randy Schmoker, a metal worker in Porcupine Creek, was in his shop when he felt the ground move. ``I thought, 'Oh good, an earthquake,' and then it got worse and worse,'' he said. Mike Heatwole, spokesman for the Alyeska Pipeline Service Co., said officials would know by midmorning Monday how long it will take to restart the pipeline. He did not know whether North Slope crude oil deliveries would be disrupted.
Earthquakes above magnitude 7 are considered major _ capable of widespread, heavy damage. In 1964, the ``Good Friday'' earthquake left 131 people dead in Alaska. Current measurements put that quake's magnitude at 9.2. Moderate earthquakes also shook the U.S. Midwest, Indonesia and Pakistan earlier Sunday, but the activity is not related nor unusual, said Waverly Person, geophysicist at U.S. Geological Survey. ``On any given day, we located about 50 earthquakes throughout the world,'' Person said. ``This to us is pretty normal.''
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