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Flores Island, in the Sunda-Banda Island group (Indonesia), where the average run-up was 16 feet, with a maximum height of 65 feet, causing 2,080 deaths. On July 12, 1993, a magnitude 7.8 earthquake in the Sea of Japan and the resulting tsunami hit Okushiri Island with an average run-up of 33 to 49 feet and a maximum of 98 feet. It killed 185 people and caused extensive property damage.
TSUNAMI CAUSED BY LANDSLIDES AND VOLCANOES
Earthquakes can cause large waves by means other than displacement beneath the ocean’s surface. On July 10, 1958, a magnitude 7.9 earthquake occurred in southeast Alaska, not far from the current site of Glacier Bay National Park, causing landslides, submarine slides, and icefalls from glaciers and producing six separate wave events. Since the earthquake occurred in a remote area, there was little damage or loss of life, but it did result in several amazing survival stories.15
The earthquake dislodged a mammoth wall of rock and pieces of ice from the glacier in the headlands of nearby Lituya Bay, creating a huge wave that roared through the bay and out into the open sea of the Gulf of Alaska at a speed of 80 to 110 knots. Some would call this a “splash,” rather than a tsunami. Whatever you choose to call it, to the crews of the three boats anchored in the bay that day, it was the biggest wave they’d ever seen.
The salmon troller Edrie, with two crew (Howard Ulrich and his six-year-old son, Howard Jr.) on board, was anchored inside the bay; two other boats were anchored near the entrance, at a place called Anchorage Cove. Ulrich heard a roaring noise and saw the wave coming as it broke around Cenotaph Island, a 320-foot-high island in the middle of the bay. The wave was steep and 66 to 98 feet high as it approached his boat. He frantically tried to maneuver, but the wave picked up Edrie, swept it up and over dry land, and then by a random chance of fate dropped it back into the bay. The other two boats (Badger, with Bill and Vivian Swanson aboard, and Sunmore, with Orville and Micki Wagner aboard) were swept out to sea over the tops of trees on a spit of land at the entrance to the bay; both sank, but the Swansons scrambled into a dinghy and survived. The Swansons reported that the wave first hit the southern side of the bay near Mudslide Creek, where