You learned from the videos in this unit that events caused by plate movements c

Question

You learned from the videos in this unit that events caused by plate movements can have deadly effects on all living organisms. During the time of the Mount St. Helens eruption, scientists who worked for the United States Geological Survey (USGS) were actually in the area conducting scientific analysis. When the volcano erupted, those men and women lost their lives.

For this assignment, you should imagine that you were in the area when Mount St. Helens erupted. Take as much time as you need to imagine what it might have been like to be at the base of a volcano as it exploded in a catastrophic eruption. Then, using Google Docs or other word processing program, write a 1-page journal entry detailing the events of the eruption. You may dramatize this, if you wish, by adding a fictional account of how someone might feel in such a situation.

Briefly, in one or two sentences, explain plate tectonics.

Describe what you might see, hear, or feel as the volcano became active—How did the ground feel? What did it sound like? What kinds of sights, sounds, smells and tastes might you experience? What thoughts went through your head?

What kind of energy would be released? Think about magma flowing up through the ground, or underground vents giving way as pressure broke through layers of rock.

Describe what takes place in the geosphere, atmosphere, hydrosphere, and biosphere as the volcano erupts.

Explanation / Answer

The first sign of activity at Mount St. Helens in the spring of 1980 was a series of small earthquakes that began on March 16. After hundreds of additional earthquakes, steam explosions on March 27 blasted a crater through the volcano's summit ice cap. Within a week the crater had grown to about 1,300 feet in diameter and two giant crack systems crossed the entire summit area. By May 17, more than 10,000 earthquakes had shaken the volcano and the north flank had grown outward at least 450 feet to form a noticeable bulge. Such dramatic deformation of the volcano was strong evidence that molten rock (magma) had risen high into the volcano.

Within 15 to 20 seconds of a magnitude 5.1 earthquake at 8:32 a.m., the volcano's bulge and summit slid away in a huge landslide - the largest on Earth in recorded history. The landslide depressurized the volcano's magma system, triggering powerful explosions that ripped through the sliding debris. Rocks, ash, volcanic gas, and steam were blasted upward and outward to the north. This lateral blast of hot material accelerated to at least 300 miles per hour, then slowed as the rocks and ash fell to the ground and spread away from the volcano; several people escaping the blast on its western edge were able to keep ahead of the advancing cloud by driving 65 to 100 miles an hour! The blast cloud traveled as far as 17 miles northward from the volcano and the landslide traveled about 14 miles west down the North Fork Toutle River.

The lateral blast produced a column of ash and gas (eruption column) that rose more than 15 miles into the atmosphere in only 15 minutes. Less than an hour later, a second eruption column formed as magma erupted explosively from the new crater. Then, beginning just after noon, swift avalanches of hot ash, pumice, and gas (pyroclastic flows) poured out of the crater at 50 to 80 miles per hour and spread as far as 5 miles to the north. Based on the eruption rate of these pyroclastic flows, scientists estimate that the eruption reached its peak between 3:00 and 5:00 p.m. Over the course of the day, prevailing winds blew 520 million tons of ash eastward across the United States and caused complete darkness in Spokane, Washington, 250 miles from the volcano.

During the first few minutes of this eruption, parts of the blast cloud surged over the newly formed crater rim and down the west, south, and east sides of the volcano. The hot rocks and gas quickly melted some of the snow and ice capping the volcano, creating surges of water that eroded and mixed with loose rock debris to form volcanic mudflows (lahars). Several lahars poured down the volcano into river valleys, ripping trees from their roots and destroying roads and bridges.

One can feel  heat and are still very hot even after months. The smell the 'rotten eggs' smell of sulphuretted hydrogen (H2S). You see fumaroles - holes in the earth's surface that are smoking, and are surrounded by sulphur crystals. My silver jewelry all turned black from the gases. One have to be careful with small children and animals because the CO2 collects in the hollows - it is heavier than air - and can knock them out. It is odorless, so if you are not aware of it until you start to suffocate. The surface of active volcanoes is very rough with pumice and volcanic bombs littering the sruface, and loose so walking is difficult, and with little vegetation.

During eruption Spring energy, seismic energy etc is released. A volcano is a vent or fissure in Earth's crust through which lava, ash, rock and gases erupt. A volcano is also a mountain formed by the accumulation of these eruptive products.Earth's crust is 40 to 250 miles (64 to 402 kilometers) thick. It is broken up into 14 major and 38 smaller pieces called tectonic plates. These plates float on a layer of magma — semi-liquid rock and dissolved gases. At the boundaries of these plates — where they move past, are pushed under, or move away from each other — magma, which is lighter than the surrounding solid rock, is often able to force its way up through cracks and fissures. Magma can explode from the vent, or it can flow out of the volcano like an overflowing cup. Magma that has erupted is called lava. The surface of the Earth is constantly affected by tectonic forces, and in certain places, the pressure accumulates enough to make the crust bend slightly. But because rock is very rigid, this stress eventually makes it snap back into a new position, releasing massive amounts of energy. These sudden movements, called seismic waves, vary widely in severity. From wobbling the water in your glass to the complete destruction of whole cities, depending on their intensity.

On May 18, 1980, Mount Saint Helens, in the state of Washington, erupted. This event altered the surrounding environment, and provided scientists with an opportunity to study the effects of volcanic eruptions on the geosphere, hydrosphere, atmosphere and biosphere. Such studies are vital because volcanic eruptions will continue to occur, and will have increasing impact on humans as people continue to settle lands closer to dormant volcanoes. The following are but a few of the myriad of interactions resulting from a volcanic eruption.

Volcano >> geosphere >> atmosphere >> hydrosphere >> biosphere
Volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. These particles serve as nuclei for the formation of water droplets (hydrosphere). Rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere). Particulate matter in the air (atmosphere) falls out, initially smothering plants (biosphere), but ultimately enriching the soil (geosphere) and thereby stimulating plant growth (biosphere).

Volcano >> geosphere >> hydrosphere >> biosphere
Volcanoes (events in the geosphere) may release a substantial amount of hot lava (geosphere), which causes mountain glaciers (hydrosphere) to melt. Mudflows (geosphere) and flooding may occur downstream from volcanoes and may inundate streamside communities (biosphere).

Volcano >> geosphere >> atmosphere >> biosphere >> geosphere
Volcanoes (events of the geosphere) release a large amount of carbon dioxide (atmosphere), the raw material for sugar production in plants (biosphere). This may increase photosynthetic production and eventually increase the amount of biomass, which, after a very long time, forms coal and oil deposits (geosphere).

Volcano >> complex interactions
Volcanoes (geosphere) may emit large quantities of sulfur dioxide (atmosphere). When atmospheric sulfur dioxide combines with water (hydrosphere), sulfuric and sulfurous acid form. Rain (hydrosphere) may bring these acids to the Earth, acidifying soils (geosphere), lakes and rivers (hydrosphere). Acidic water leaches nutrients from the soil (geosphere) into the water table (hydrosphere), making the soil less fertile for plants (biosphere), and the subterranean water supply (hydrosphere) less potable for humans (biosphere). Acid rain falling on lakes and streams reduces the pH of the water (hydrosphere), which may result in a decrease in phytoplankton and zooplankton growth (biosphere). If photosynthesis is reduced, atmospheric concentrations of carbon dioxide can build up and stimulate global warming (atmosphere) which may contribute to increased melting of glaciers (hydrosphere).

In general

1.      Atmosphere:  

Gases surrounding a celestial body make up its atmosphere.

For short term speaking, when the volcano eruption, all the ash particles would throw up into the atmosphere. The volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operation tempererature. For long term speaking, volcanoes eruption could produce about 5*10^11kg of CO2 per year. For the research and the calculation show that the volcanism produced about 3% of the total CO2  with the other 97%coming from the other anthropogenic sources.

2. Hydrosphere:

The part of the earth composed of water id called the hydrosphere.

Volcanoes can affect the hydrosphere through the eruption, the lava and volcanic ash could cause the air pollution also through the raining go in to the water cycle ad pollute the water as well. Also, the ocean’s water temperature will rise.

3.       Biosphere:

The volcano eruption could kill the plants and the animals live nearby because of the hot lava and poisonous gases. Therefore, the raining water which contains the volcano ash could influence the plants growth in long term.

4.       Lithosphere:

The earth’s crust and the upper layer of its mantle make up the system call lithosphere. The force due to the eruption can change, destroy or create the new type of rock and landform such as igneous rocks.  Volcanic eruption often happens near the boundaries of tectonic plates.  

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