A major earthquake of 7.4 magnitude struck in the Pacific Ocean more than 1,000 miles west of Anchorage on Thursday, prompting a brief tsunami warning for part of the remote Aleutian Islands chain. No damage or injuries were reported. The warning, which extended for roughly 800 miles — from Unimak Pass, northeast of Dutch Harbor, westward to Amchitka Pass, west of Adak Island — was canceled after a little more than an hour. A tsunami wave measuring just 6 centimeters tall was recorded at Nikolski, a tiny Aleut village on the island of Umnak, and a 10-centimeter wave was observed at Adak, said Becki Legatt, a spokeswoman for the West Coast and Alaska Tsunami Warning Center in Palmer, Alaska. The coast of the entire Alaska peninsula and all of the Alaska mainland were never considered to be threatened.

The Trans Alaska Pipeline shut down on Saturday after a leak was discovered at the intake pump station at Prudhoe Bay, constricting supply in one of the United States’ key oil arteries. Alyeska Pipeline Service Co., the operator of the 800-mile (1,280 kilometre) line which runs from the Prudhoe Bay oilfield to the tanker port of Valdez, said the leak was discovered Saturday morning. Oil producers are in the process of cutting output to 5 percent of the normal rate of around 630,000 barrels per day. There is no estimate yet of how long the pipeline — which carries about 12 percent of U.S. oil production — will be shut down or when normal production can resume, said Alyeska spokeswoman Michelle Egan.