ANCHORAGE, Alaska (Reuters) - A 7.1 magnitude earthquake struck on Friday in the Aleutian Islands off Alaska, the US Geological Survey reported, prompting a tsunami warning for a portion of Alaska's coast that was lifted after an hour. The warning had covered areas of the Aleutians that included Unalaska-/Dutch Harbor, the region's biggest community, and Adak. Meanwhile, a 6.4 magnitude earthquake rocked northern Argentina Friday, but the epicenter was almost 600 kilometers (370 miles) underground and there were no immediate reports of casualties or damage.