Alaska earthquake triggers tsunami warnings

Residents in some communities evacuate after magnitude-8.0 tremor

A shakemap provided by the United States Geological Survey (USGS) shows the magnitude-8.0 earthquake registered 24 km south east of Little Sitkin Island (USGS)

A strong earthquake near Alaska's Aleutian Islands triggered a tsunami warning on Monday, but only small waves measuring several inches hit coastal communities.

The National Tsunami Warning Center cancelled all tsunami warnings late on Monday afternoon, about four hours after the earthquake struck.

The magnitude-7.9 earthquake was centred about 13 miles (21 kilometers) south-east of Little Sitkin Island, or about 1,400 miles (2,250 kilometers) south-west of Anchorage.

There were no reports of damage, said Jeremy Zidek, a spokesman for the Alaska Department of Homeland Security and Emergency Management.

Residents in some communities like Adak, which were first in line for the tsunami, did evacuate.

“We're seeing water leave our bay, so we do have everybody up on the Bering Hill area, where our primary evacuation centre is at,” City Manager Layton Lockett told The Associated Press by telephone as he gathered some paperwork before heading out to join about 300 residents at the centre.

After the warning was cancelled, he said everyone in town remained on alert. If anything significant were to happen, a siren will sound and people would go back on the hill as soon as possible, he said.

About 200 miles (320 kilometers) west, a tsunami wave of about 7 inches (18 centimeters) was reported at Amchitka Island, Zidek said. The wave diminished the further it travelled, reaching only a couple of inches at Adak and Shemya.

But the earthquake was widely felt in Adak, one of the largest cities in the affected area. Shaking could also be felt in Shemya and other villages along the island chain.

Lockett said the prolonged shaking from the temblor put it in the top 10 of those felt recently.

“Everybody in our building went out, watching the vehicles shake and waiting for it to end,” he said.

Shemya Island is where the US military operates Eareckson Air Station, which serves mainly as an early warning radar installation. Air Force officials said there was no damage to the air station.

Amchitka Island is where the government tested nuclear weapons underground in the 1960s and '70s. The tests included one of the United States' largest nuclear explosions.

Monday's earthquake was initially reported with a magnitude of 7.1, but that was upgraded to 8.0, said Natasha Ruppert, a seismologist with the Alaska Earthquake Center. In the review of data hours after the quake, the magnitude was downgraded to 7.9.

There were several strong aftershocks, with magnitudes reaching 5.9. Dave Nyland, a geophysicist at the National Tsunami Warning Center, said those would be too small to trigger a tsunami.

AP