On May 21, 1960, the first tremor of a series hits Valdivia, Chile. By the time they end, the quakes and their aftereffects kill 5,000 people and leave another 2 million homeless. Registering a magnitude of 7.6, the first earthquake was powerful and killed several people. It turned out to be only a foreshock, however, to one of the most powerful tremors ever recorded.
At 3:11 p.m. the following afternoon, an 8.5-magnitude quake rocked southern Chile. The epicenter of this tremendous shaking was just off the coast under the Pacific Ocean. There, the Nazca oceanic plate plunged 50 feet down under the South American plate. The earthquake caused huge landslides of debris down the mountains of the region, as well as a series of tsunamis in the coastal region of Chile. At 4:20 p.m., a 26-foot wave hit the shore, taking most structures and buildings with it when it receded. But the worst was still to come. Minutes later, a slower 35-foot wave rolled in; it is estimated that this wave killed more than 1,000 people, including those who had thought they had moved safely to high ground.
Given the tremendous force of the quake, the death toll could have been far higher. A foreshock 30 minutes prior to the large tremor had forced many people outside, where they were less vulnerable to structural collapses. In addition, the people of the area knew to expect a tsunami and most evacuated the coast immediately.
After leaving Chile, the tsunami traveled hundreds of miles west toward Hawaii, the Philippines and Japan, where hundreds also died. In fact, the waves set off by this earthquake bounced back and forth across the Pacific Ocean for a week. Aftershocks were recorded for a full 30 days after the main tremor.