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Unformatted text preview: Hilo Honolulu P a c i f i c O c e a n Lo‘ihi K ï lauea Mauna Loa Hual ä lai Haleakal ä Hawai‘i Maui Moloka‘i Kaho‘olawe Lana‘i O‘ahu Kaua ‘ i Ni‘ihau U.S. Department of the Interior U.S. Geological Survey USGS Fact Sheet 074–97, version1.1 Revised June 2000 Living on Active Volcanoes—The Island of Hawai ‘ i U.S. GEOLOGICAL SURVEY—REDUCING THE RISK FROM VOLCANO HAZARDS P eople on the Island of Hawai ‘ i face many hazards that come with living on or near active volca- noes. These include lava flows, ex- plosive eruptions, volcanic smog, damaging earthquakes, and tsunamis (giant seawaves). As the population of the island grows, the task of reduc- ing the risk from volcano hazards be- comes increasingly difficult. To help protect lives and property, U.S. Geo- logical Survey (USGS) scientists at the Hawaiian Volcano Observatory closely monitor and study Hawai ‘ i’s volcanoes and issue timely warnings of hazardous activity. Late in the evening of June 1, 1950, after many residents of Ho ÿ okena-mauka village on the west coast of the Island of Hawai ÿ i had already gone to bed, Mauna Loa Volcano suddenly began to erupt. Hot, glowing lava poured from fissures and rushed down the southwest flank of the volcano. In only 3 hours, the swiftly flowing lava traveled 14 miles and entered the village. The darkness was lit by flames as the molten lava con- sumed several houses and the Post Office. By daybreak, lava flows had crossed the area’s only road in two places, cutting off all escape routes. Fortunately, the residents of Ho ‘ okena-mauka escaped unharmed, but for some it was a close call. The Island of Hawai ‘ i is composed of five volcanoes, two of which—Mauna Loa and K ï lauea—have erupted repeatedly in this century. Another of these volcanoes, Hual ä lai, last erupted in 1801 and has the po- tential to erupt again within our lifetime. Most eruptions at Hawaiian volcanoes are not explosive and are characterized by the relatively quiet outflow of very fluid lava. These eruptions can still be deadly, because the lava may be erupted in huge volumes, and on steeper slopes fluid lava can rapidly travel many miles from its source. Mauna Loa, the world’s largest active vol- cano, last erupted in 1984. During that 3- week-long eruption, rivers of lava came within 4 miles of the outskirts of the coastal city of Hilo. Most of Mauna Loa’s eruptions in the last 150 years began at eruption sites (vents) near the volcano’s remote 13,677- foot-high summit. About half of these sum- mit eruptions quickly developed into erup- tions on the flanks of the volcano. Mauna Loa's flank eruptions usually occur along one of two zones of weakness, called rift zones, that extend partway down its northeast and southwest slopes. A few eruptions also have taken place from isolated vents on the volcano’s northern slope....
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This note was uploaded on 07/31/2011 for the course GLY 2030 taught by Professor Kruse,s during the Fall '08 term at University of South Florida.
- Fall '08