1980 Mount St. Helens | |
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| Total costs | N/A |
| Deaths | 57 |
On March 27, 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of phreatic blasts occurred from the summit and escalated until a major explosive eruption took place on May 18, 1980. The eruption, which had a Volcanic Explosivity Index of 5, was the most significant to occur in the contiguous United States since the much smaller 1915 eruption of Lassen Peak in California. It has often been declared the most disastrous volcanic eruption in U.S. history. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes caused by an injection of magma at shallow depth below the volcano that created a large bulge and a fracture system on the mountain's north slope. An earthquake at 8:32:11 am PDT (UTC−7) on Sunday, May 18, 1980 caused the entire weakened north face to slide away, creating the largest landslide in recorded history. This allowed the partly molten rock, rich in high-pressure gas and steam, to suddenly explode northward toward Spirit Lake in a hot mix of lava and pulverized older rock, overtaking the landslide. An eruption column rose 80,000 feet (24 km; 15 mi) into the atmosphere and deposited ash in 11 U.S. states and two Canadian provinces. At the same time, snow, ice, and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. Less severe outbursts continued into the next day, only to be followed by other large, but not as destructive, eruptions later that year. Thermal energy released during the eruption was equal to 26 megatons of TNT.About 57 people were killed, including innkeeper and World War I veteran Harry R. Truman, photographers Reid Blackburn and Robert Landsburg, and geologist David A. Johnston. Hundreds of square miles were reduced to wasteland, causing over $1 billion in damage (equivalent to $3.5 billion in 2020), thousands of animals were killed, and Mount St. Helens was left with a crater on its north side. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, but afterward, the railroad donated the land to the United States Forest Service. The area was later preserved in the Mount St. Helens National Volcanic Monument.
Source: Wikipedia 2005 Nias-Simeulue earthquake | |
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| Total costs | N/A |
| Deaths | 1313 |
The 2005 Nias–Simeulue earthquake occurred on 28 March off the west coast of northern Sumatra, Indonesia. At least 915 people were killed, mostly on the island of Nias. The event caused panic in the region, which had already been devastated by the massive tsunami triggered by the 2004 Indian Ocean earthquake, but this earthquake generated a relatively small tsunami that caused limited damage. It was the third most powerful earthquake since 1965 in Indonesia. The earthquake occurred at 16:09:37 UTC (23:09:37 local time) on 28 March 2005. The hypocenter was located 30 kilometres (19 mi) below the surface of the Indian Ocean, where subduction is forcing the Indo-Australian Plate to the southwest under the Eurasian Plate's Sunda edge. The area is 200 kilometres (120 mi) west of Sibolga, Sumatra, or 1,400 kilometres (870 mi) northwest of Jakarta, approximately halfway between the islands of Nias and Simeulue. Seismic recordings give the earthquake a moment magnitude of about 8.6, and effects were felt as far away as Bangkok, Thailand, over 1,000 kilometres (620 mi) away.
Source: Wikipedia
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