Magnitude 7.9 Quake Rocks Alaska’s Interior

A major earthquake rocked a sparsely populated area of interior Alaska early Sunday afternoon, damaging supports to the trans-Alaska oil pipeline and opening 6-foot cracks in highways and roads.

The magnitude 7.9 quake, centered 90 miles south of Fairbanks, was strongly felt in Anchorage, about 270 miles to the south. It hit at 1:13 p.m. Alaska Standard Time, said Bruce Turner of the West Coast & Alaska Tsunami Warning Center in Palmer.

Only one injury was reported; a 76-year-old woman in Mentasta broke her arm after slipping on stairs during the quake, said State Patrol spokesman Greg Wilkinson.

“It shook for a good 30 seconds,” Turner said, adding that it did not generate a tsunami.

Support structures were damaged on the trans-Alaska oil pipeline, but the pipeline itself was intact, said Mike Heatwole, spokesman for the Alyeska Pipeline Service Co.

The quake triggered a detection system, and operators manually shut down the pipeline about 2 p.m., Heatwole said.

In five locations, vertical support members, the H-shape devices that hold the aboveground portions of the pipeline, were damaged. In eight places, the “shoes” that connect the pipeline to the vertical support members were on the ground, leaving the pipeline suspended, he said.

Heatwole said company officials may know by midmorning today how long it will take to restart the pipeline. He did not know whether North Slope crude oil deliveries would be disrupted.

The earthquake occurred on the Denali fault and had a shallow depth, said John Lahr, geophysicist at the U.S. Geological Survey’s National Earthquake Information Center in Golden, Colo. Shallow earthquakes generally are felt over a wider area.

Troopers responded to several reports of damaged roads in the area, said Lt. Lee Farmer.

Numerous roads developed wide cracks, including the Alaska Highway near Northway, 256 miles southeast of Fairbanks. The Richardson Highway, which parallels the trans-Alaska pipeline between Valdez and Fairbanks, was closed near Paxson after gaps opened that were 2 to 6 feet wide and 5 feet deep, Wilkinson said.

The worst reports of damage were along a 2-mile stretch of the Tok Cutoff, which leads from the Alaska Highway to south-central highways connected to Anchorage.

There were hundreds of yards of 6-foot openings in the road and numerous rock slides.

Fuel tanks were knocked over in Slana, which has no electric utility; families use diesel fuel to power generators.

Sharrel Webster said she was likely to lose food in her freezer. A semitrailer the family uses for storage tipped over on its side.

Jay Capps, who owns a small grocery store midway between Tok and Glennallen, said he felt a low-level shaking for 15 or 20 seconds before the quake hit.

“It shook so bad you could not stand up on the front porch,” Capps said. “It sounded like the trees were breaking roots under the ground.”

Earthquakes above magnitude 7 are considered major -- capable of widespread, heavy damage.

A moderate earthquake shook the central Plains on Sunday. The 4.3 quake hit about 30 miles northwest of O’Neill, Neb., the geological survey said.