what happens when a violent volcano erupts?

Question

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Answer 1

The eruption of Mount St. Helens, on May 18, 1980 was photographed and measured in lots of ways. The words below are from USGS websites/publications not copyrighted. But--they are excerpts and should have quotes if used in a report:
For weeks before the big eruption, there were earthquakes and small "phreatic explosions". By mid-April, the surface of the volcano was bulging.
At 0832 on May 18, a complex earthquake (M=5.1) shook the volcano, probably causing (but possibly caused by) a huge, 2.7-cubic-kilometer-landslide that in three different blocks successively removed the bulge and upper 400 meters of the volcano (Voight, et.al., 1981, 1983), leaving a 600-meter-deep crater 2 kilometers wide rim-to-rim. The landslide quickly developed into a debris avalanche that sped at 110-240 kilometers/hour for 24 kilometers down the North Fork Toutle River; arms of the avalanche entered spirit Lake, 8 kilometers from the summit, and overtopped 300-380-meter high Johnston Ridge north of the Toutle. The avalanche buried the Toutle valley to a depth of nearly 50 meters.

The landslide removed confining pressure on the cryptodome and its surrounding hydrothermal system. Juvenile gas was rapidly released from the cryptodome and superheated groundwater flashed to steam, causing a blast that exploded laterally from the collapsing north flank. The blast, called a "stone wind" by local journalists, knocked down most trees (the equivalent of about 150,000 houses) in a 600-square-kilometer area.
Soon after the blast, a lahar rushed down the South Fork Toutle River and several streams draining the south and east flanks of the volcano. Whether water for these lahars came from snowmelt or from groundwater ejected by the eruption is hotly argued. The largest lahar, down the North Fork Toutle, did not start until early afternoon; it was fed as the debris avalanche dewatered (Janda, et.al., 1981). In addition to causing havoc along the rivers themselves, the lahars fed so much debris into the columbia River that 31 ships were stranded in upstream ports until the 4-meter-deep channel was dredged to its pre-eruption depth of 12 meters -- the first in a series of similar dredgings to maintain Portland (Oregon) as a seaport.

A strong, vertically directed explosion of ash and steam began very shortly after the lateral blast. The resulting eruptive column rose very quickly. In less than 10 minutes, the ash column reached an altitude of more than 12 miles and began to expand into a characteristic mushroom-shaped ash cloud. Near the volcano, the swirling ash particles in the atmosphere generated lightning, which in turn started many forest fires. As the eruption roared on, the major part of the ash cloud drifted downwind in an east-northeasterly direction, although ash that rose above the high-speed (Jet-stream) winds followed other paths determined by complex wind directions.

If you go to one of the USGS websites below, they will have links to other USGS sites talking about violent volcanoes.

Answer 2

When a volcano erupts it extrudes huge quantities of basaltic lava that gradually build a wide mountain with a shield-like profile. The lava flows are generally very hot and very fluid, contributing to long flows. The largest lava shield on Earth, Mauna Loa, rises over 9,000 m from the ocean floor, is 120 km in diameter and forms part of the Big Island of Hawaii.
Quiet eruptions spread out basaltic lava in flat layers. The buildup of these layers form a broad volcano with gently sloping sides called a shield volcano. Examples of shield volcanoes are the Hawaiian Islands.

Answer 3

It relies upon on the type of eruption, the quantity of ejected textile etc. cave in of the cone to type a caldera is one threat. Lahars could take place after an eruption ceases, while ash is mobilised in water to type a unfavorable slurry. some volcanoes erupt extra or much less continuously, some in basic terms intermittently. seek on volcanoes + aftermath for further documents.

Answer 4

Owww - big bang Mum!
Oh, and lots of molten material spurts forth from a big hole, usually at or near the top of a mountain but sometimes under the sea (you can't trust the buggers nowadays!) and sometimes people get hurt and trees and plants and anything that can't get out of the way quickly enough tend to get destroyed by the fire or heat. Not at all a nice thing to happen! Then there's all the dust and steam which goes up into the air... and Oh, why did I bother......

Answer 5

violent volcano eruption

Answer 6

It explodes and throws out rocks, gases and lava. It would also cause very large tremors too. Wouldn't want to be within a hundred miles or more from it.

Answer 7

vindeloo

Answer 8

people run and scream

Answer 9

people go bye-bye