8.0 Major Earthquake and Tsunami strike Alaska

A magnitude 8.0 earthquake struck deep under the ocean floor near Alaska's Aleutian Islands, triggering shaking that could be felt for vast distances and prompting a tsunami warning, the U.S. Geological Survey and National Tsunami Warning Center said. The tsunami warning, later downgraded to an advisory, prompted the evacuation of about 150 residents of the town of Adak to higher ground, according to media reports. It was not immediately clear whether the quake caused injuries or damage. The quake was so large and deep that it triggered dozens of aftershocks within an hour and prompted enough shaking that it will be picked up by seismometers around the world over the next 24 hours, said Mike West, a seismologist who serves as director of the Alaska Earthquake Center.The earthquake was widely felt in Adak, one of the largest cities in the affected area about 1,300 miles southwest of Anchorage. Shaking could also be felt in Shemya and other villages along the sparsely populated Aleutian Islands. Shemya Island is where the U.S. military operates Eareckson Air Station, which serves mainly as an early warning radar installation. The earthquake recorded at 12:53 p.m. Alaska Daylight Time was initially reported with a magnitude of 7.1, but that was upgraded to 8.0, Ruppert said. The quake was centered about 13 miles southeast of Little Sitkin Island or 25 miles north Amchitka Island.There were no initial reports of damage in Adak or on Shemya Island, said Ian Dickson, website manager for the Alaska Earthquake Information Center. Dickson said there were 17 measurable aftershocks in the two hours after the quake. First estimates put the quake at magnitude 8.0, and prompted a tsunami warning. The strength was subsequently set by the U.S. Geological Survey at 7.9 magnitude and the tsunami warning was scaled back to an advisory.