A strong earthquake has struck off the coast of the northwestern U.S. state of Alaska.

The U.S. Geological Survey says the 6.1 magnitude quake Saturday was centered near the Aleutian Islands in the Pacific Ocean, some 970 kilometers southwest of the city of Anchorage. The quake was measured at a depth of 48 kilometers.

There have been no reports of injuries or damage.

Saturday's tremor came three weeks after a powerful 7.2 magnitude earthquake shook the same area. The Alaska Tsunami Warning Center issued a tsunami warning for the coastal areas of Amchitka Pass to Dutch Harbor, but lifted it about an hour after the quake struck.