A powerful earthquake struck off the coast of Chile at 3:54 PM Pacific Daylight Time. The quake was at a depth of 15.5 miles and was 145 Miles NNW of Santiago. The quake struck in the Nazca Plate Region, which is one of the most active earthquake zones on the Pacific Rim and in the world. The quake took place on the South American arc, which marks the boundary between the Nazca Plate and the South American Plate and stretches approximately 6,000 miles along the South American Coast. The relatively shallow depth of the quake and the slow upward gradient of the ocean floor toward land in the region has caused the tsunami warning, but no serious wave action ensued.