ANCHORAGE, Alaska (AP) — A powerful earthquake struck off an island in the Gulf of Alaska early Tuesday, prompting a tsunami threat that sent people living along the state's southern coast and western Canada fleeing for higher ground. After a few intense hours, the tsunami warning was canceled, allowing people to return home from shelters. There were no immediate reports of damage, not even on Kodiak Island, the closest land to the epicenter of the magnitude 7.9 quake.