ANCHORAGE — The US Coast Guard warned people in far southern Alaska to take precautions after a tsunami warning was issued for coastal areas of Alaska and the Pacific Northwest. The warning was sparked by a strong earthquake Saturday night that struck off the west coast of Canada. There were no immediate reports of damage. The US Geological Survey said the 7.7-magnitude earthquake hit in the Queen Charlotte Islands area. The National Weather Service issued a warning for coastal areas of southern Alaska, Northern California, Oregon, and Washington state.