On May 18, 1980, Mount St. Helens in Skamania County, Washington, United States, erupted. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes. An eruption column rose 80,000 feet into the atmosphere and deposited ash in 11 U.S. states and two Canadian provinces. Thermal energy released during the eruption was equal to 26 megatons of TNT. Approximately 57 people were killed directly, including innkeeper Harry R. Truman, photographers Reid Blackburn and Robert Landsburg, and geologist David A. Johnston.
About 1980 eruption of Mount St. Helens in brief
On May 18, 1980, Mount St. Helens in Skamania County, Washington, United States, erupted. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes. An eruption column rose 80,000 feet into the atmosphere and deposited ash in 11 U.S. states and two Canadian provinces. Thermal energy released during the eruption was equal to 26 megatons of TNT. Approximately 57 people were killed directly, including innkeeper Harry R. Truman, photographers Reid Blackburn and Robert Landsburg, and geologist David A. Johnston. Hundreds of square miles were reduced to wasteland, causing over USD 1 billion in damage, thousands of animals were killed, and Mount St. Helens was left with a crater on its north side. The area was later preserved, as it was, in the Mount St Helens National Volcanic Monument. It has often been declared the most disastrous volcanic eruption in U. S. history. It was the most significant to occur in the contiguous 48 states since the much smaller 1915 eruption of Lassen Peak in California. A second eruption was detected on April 1, prompting an executive order by Washington Governor Lee Ray Dixy to declare an emergency. On April 3, a series of separate-three separate-bursts outbursts were reported out out of the volcano. On March 27, phreatic eruptions ejected and smashed rock from within the old summit crater, excavating a new crater 250 feet wide, and sending an ash column about 7,000ft into the air.
At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series that reached as far as the Columbia River, nearly 50 miles to the southwest. This was followed by more earthquake swarms and series of steam explosions that sent ash 10,000 to 11,000 ft above their vent. Most of this ash fell between three and 12 miles from its vent, but was carried 150 miles south to Bend, Oregon, or 285 miles east to Spokane, Washington. The flame was visibly emitted from craters and was probably created by burning gases generated by burning gas and electricity generated by rolling ash clouds that were up to two miles long. It is the only volcano in the United States to have emitted such a large amount of flame from a vent, and the only one in the world to have done so in such a short period of time. A total of 174 shocks of magnitude 2. 6 or greater were recorded during those two days, including an earthquake registering 5. 1 on the Richter scale. Shocks of magnitude 3. 2 or greater occurred at a slightly increasing rate during April and May with five earthquakes of magnitude per day in early April, and eight per day the week before May 18. A shallow magnitude 4. 2 earthquake centered below the volcano’s north flank, signaled the volcano’s return from 123 years of hibernation.
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