1792 Eruption of the Unzen Volcano Essay

654 Words Apr 2nd, 2013 3 Pages
Mike Lillis
GEO 100
Unzen, Japan 1792 In 1792 Mount Unzen erupted which devastated Japan. Mount Unzen is a group of active overlapping stratovolcanoes. They are located on the island of Kyushu which is Japan’s most southern main island. Not only was the Eruption deadly but the Mayu-Yama Lava domes collapsed which triggered a Mega-Tsunami that killed nearly 15,000 people. This was one of Japans worst volcanic disasters. The Volcano has been dormant for 198 years until the early 1990’s when the volcano became active and erupted again in November 1991 creating a pyroclastic flow which killed 43 people. A Pyroclastic flow is a fast moving current of hot gas and rock known as tephra. The flow all depends on the density and gradient
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It travels extremely fast and is very dangerous. The threat of falling ash and lapilli also play a role as seen in this volcano. The ash can bury the landscape which kills all plants and crops in the area. It can cause damage to people’s homes and can destroy properties. Flood waters also easily move tephra as deadly lahars. The 1792 eruption triggered a landslide of large masses of material near the vent on the steep slope. The most deadly part of the Unzen eruption was the Tsunami it created in the Ariake Sea. The tsunami struck the Higo Province on the other side of Ariake Bay before bouncing back and hitting Shimabara again. Out of an estimated total of 15,000 fatalities, around 5,000 are thought to have been killed by the landslide, around 5,000 by the tsunami across the bay in Higo Province, and a further 5,000 by the tsunami returning to strike Shimabara. The waves reached a height of 33 to 66 ft., classifying this tsunami as a small mega-tsunami. At the Osaki-bana point Futsu town, the waves locally grew to a height of 187 ft. due to the effect of sea bottom topography. This Volcano had a major effect on the surrounding areas. Not only did it damage and destroy so many people’s lives but the area was devastated. The Volcano flowed and erupted for a month before the explosion took place. The landscaping around the islands has shifted and new islands have

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