Lisboa (Lisbon), Portugal, was the hub of a great seafaring nation. Early in the morning of November 1, 1755, a huge earthquake occurred somewhere out in the Atlantic to the west of the city. Terrible destruction resulted—so much that although no instruments existed at that time, seismologists have estimated its magnitude as 9.0. Around an hour later, waters in the bay receded and the first wave hit with a height of 50 feet. It rushed inland, completing the destruction caused by the earthquake. It was followed by two more waves. An estimated 60,000 persons died and approximately 80 percent of the city was destroyed.

EXAMPLES OF RECENT TSUNAMI

Following an earthquake on August 13, 1868, a 70-foot-high tsunami swept over Arica, Peru (now part of Chile). The U.S. gunship Wateree, a side-wheel steamer, was one of several ships in the harbor that witnessed the town collapse as the earthquake struck. At first the sea receded, causing the Wateree to settle on her flat bottom. This perhaps saved her, for when the actual wave came rushing in, she was carried 3 miles up the coast and nearly 2 miles inland—over tall buildings, dams, and trees. As the waters receded, Wateree was deposited upright in the desert next to a Peruvian man-of-war, America. In this position, with no possibility of returning to the sea, the Wateree maintained operations in the desert for a while, assisting in relief efforts while waiting for a U.S. vessel to come retrieve the crew. Since the town was devastated—and much of its population dead—the crew lived on the boat. The crew planted a vegetable garden nearby, and when the captain was “piped ashore,” it was on a burro, rather than the captain’s gig.7

While tsunami are most commonly caused by submarine earthquakes, they can also be caused by landslides, volcanoes, or meteorite impacts in the ocean. Geoscientist Edward Bryant calculates that in the Pacific region during the last 2,000 years, 82 percent of tsunami have been caused by earthquakes, around 5 percent by volcanoes, 5 percent by landslides, and 8 percent by unknown means.8 The damage caused by tsunami, and the wave heights created, depend not only on the magnitude of the earthquake or other cause but also on the nearshore con-



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