What happened in the 1980 Mt. St. Helens eruption?
98058
Gases built up over a period of time under the solid rock, which contained the gas until it built up too much pressure. The gases escaped in an incredible explosion more powerful than some nuclear weapons. The damage to the surrounding area was devastating, but far from permanent. In fact, plants and animals are already returning to the explosion area.
764265
Try this website:  http://volcano.und.edu/
567045
It WILL erupt again - it's not a matter of IF, but rather When and How Big?  It is being monitored very closely by geophysicists and volcanologists at present.\n\nMost recently the volcano erupted in the 1940s (not that long ago!  It was a minor eruption).  For more information, check out the link below.
68067
Fifty-seven people were killed and 200 homes, 47 bridges, 15 miles (24 km) of railways and 185 miles (300 km) of highway were destroyed. The eruption caused a massive debris avalanche, reducing its summit from 9,677 feet (2,950 m) to 8,364 feet (2,550 m) in elevation and replacing it with a mile-wide (1.5 km-wide) horseshoe-shaped crater (see geology section or 1980 eruption of Mount St. Helens for more detail). The debris avalanche from the 1980 eruption was up to 2.3 cubic kilometers (0.7 cubic miles)in volume, making it the largest in recorded history. However, the scale of it still pales in comparison to far larger debris avalanches that have occurred in the geological past elsewhere on Earth.
500047
Several things happen when a volcano is about to erupt, some of the most obvious are: \n\n1.The number and size of earthquakes increase in and around the volcano. \n\n2.The ground deforms or "bulges" at the eruption site. \n\n3.A lot more gas comes out of the volcano.
1036871
Because Mt. St. Helens is a volcano.
425045
The answer is: D. Volcanoes that have large amounts of silica\n\nHere is the reason why it is D:\n\nMagma that contains high amounts of silica is very viscous. That means it is very thick. Because of its thickness, gases can not escape & will build up behind the magma. When the pressure builds up enough, an explosion occurs. Large chunks of lava rock are thrown from the volcano in all directions. The debris fallout from these types of eruptions is extremely dangerous!\n\nIn 1980, Mt. St. Helens was an explosive composite volcano. Half the mountain was gone in a matter of minutes. The problem with that particular volcano was not the falling rock debris (few people). In fact w/ St. Helens, it was the ash which is small particles of volcanic glass (a.k.a. silica). These minute particles of glass can cut your lungs. Also, people living & camping down below the mountain were caught up in mudflows caused by the melted snowcaps. Also, pyroclastic flows can race down the mountainside at tremendous speeds. Anyone caught in the way would be annihilated.\n\nSea water can cause explosive steam eruptions but this occurs in submarine volcanoes (underwater). No one is around to be in its way.\n\n:)
717408
Usually there are warning signs that something is happening. Active volcanos such as Mt St Helens are continusly monitored for changes such as increase in earthquake activity, change in the shape of the volcano. Scientists can actually see changes to the shapre of hte volcano by GPS surveys. Like what is happening in the Pacific at teh moment (cant remember the name of the volcano just now) they know something is going to happen, but they cant place a time on it, so they have evacuated hte people. Most people are evacuated before hte volcano blows, but those that have ignored pleas do so at they're own risk. And yes as the dude above me pointed out, by means of a road.
579528
famous 1902 volcanic eruption, most of the damage i seem to remeber being caused by a pyroclastic flow, killed about 27,000 people. I'm not sure if that is a myth or not!
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Go here:\n\nhttp://www.fema.gov/kids/volcano.htm
932528
I've experienced a few small ones myself. When I was studying a volcano in South America a few years back, there was an eruption on the main vent that killed three people.\nBut damn... volcanoes are LOUD. There was a brief moment when the explosion happened, and I sort of went deaf for a few moments (if you could call it that). When I turned around and looked up the slope , I saw a large cloud of debris, and within seconds there were rocks falling all over the place. It is quite scary when larger rocks hit the ground, because you never really know where they'll fall unless you keep your eyes focused on the airborne ones.\nAs you can imagine, I left very quickly. I didn't hear about the deaths until the very next day. My friends tell me I was lucky.
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San Francisco Earthquake History 1880-1994\nToo many for me to list them for you...hope this is what you were looking for. :)
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See for yourself:\n\nhttp://www.solcomhouse.com/volcano.htm\nhttp://volcano.und.edu/vwdocs/frequent_questions/group10_new.html\nhttp://www.exn.ca/volcanoes/causes.cfm\nhttp://vulcan.wr.usgs.gov/Outreach/AboutVolcanoes/where_do_volcanoes_occur.html\nhttp://library.thinkquest.org/10136/volcano/volctq.htm\nhttp://en.wikipedia.org/wiki/Volcano\n\nMore random links I keep at hand for God knows what uses.
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I believe the most recent volcano - is 14 November 2006 at Home Reef, Tonga Island, Tonga.\n\nPumice rafts originally reported to have been from Metis Shoal are now confirmed to have originated from an island-building eruption of the submarine Home Reef volcano. On 12 August, possibly four days after the beginning of the eruption, a sailor spotted the new island after encountering pumice rafts the previous day. The encounter was written in an on-line journal that described the island as four-peaked. A central crater produced steam plumes and occasional bursts of tephra. Data from the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite showed that sulfur dioxide emissions from the Home Reef area began on 8 August, peaked during 8-9 August, and ceased on 15 August. Based on ASTER satellite imagery from 4 October, the island was an estimated 1 km long with an area of 0.23 square km. The temperature of a small lake on the island was 64.7?C. The island was 0.15 square km, based on ASTER imagery from 12 October. Geologic Summary: Home Reef, a submarine volcano midway between Metis Shoal and Late Island in the central Tonga islands, was first reported active in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12-km-high eruption plume, copious amounts of floating pumice, and an ephemeral island 500 x 1500 m wide, with cliffs 30-50 m high that enclosed a water-filled crater. \n\nI hope the above is the right answer you are looking for.
73089
Mount Saint Helens is an active composite cone
1010195
Long before any recorded human history in Yellowstone, a massive volcanic eruption spewed an immense volume of ash that covered all of the western U.S., much of the Midwest, northern Mexico and some areas of the eastern Pacific Coast. The eruption dwarfed that of Mount St. Helens in 1980 and left a huge caldera 43 miles by 18 miles (70 km by 30 km) sitting over a huge magma chamber (see Geology section and Yellowstone Caldera). Yellowstone has registered three major eruption events in the last 2.2 million years with the last event occurring 640,000 years ago. Its eruptions are the largest known to have occurred on Earth within that timeframe, producing drastic climate change in the aftermath
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Curiously, I could not find a comprehensive listing.  This site might be helpful, however, or at least give you a start.\n\nhttp://dir.yahoo.com/Science/Earth_Sciences/Geology_and_Geophysics/Volcanology/Volcanoes