At 10 am, the eruption began. Ash toppled over the helpless Pompeian people, killing everything and everyone in its path.
Becoming one the largest volcanic eruptions in U.S history. The devastation caused by the volcano was wide spread. Many plants, countless numbers of animals and insects were killed, along with 57 people who were miners, scientists, and one journalist. In addition to this, further damage to human settlements and facilities occurred. The area is subjected to frequent earth movements and has a long history of volcanic activity.
This greatly relates to the plate margin the volcano or volcanic belt is situated upon. There are three areas on the crust where volcanoes can form. These are; over hotspots, along constructive plate margins and along destructive plate margins. The area the volcano forms on usually determines the type of lava found at the volcano. Effusive volcanoes are more commonly formed at constructive plate margins where plates diverge.
In which ways does volcanic activity vary in relation to the type of plate margin along which it occurs? (10 Marks) Volcanic activity can occur at constructive or destructive plate margins, but it can also occur at hotspots in which no plate margin is involved. At destructive margins two plates which are moving together can be either both oceanic plates or one continental and the other oceanic. In the case of one continental plate and one oceanic plate, volcanic eruptions are very violent and emit andesitic or rhyolitic lava. These types of lava are very viscous due to its high silica content.
Mid-ocean volcanic ridges are formed where the ocean floors split and move apart. Hawaii have followed a different pattern, forming from magma released from individual hotspots in the mantle. The inner parts of the continents have few volcanoes, almost all the land volcanoes are located on are less than 100 km from the coast. An example of this is Mount Pinatubo, which is located roughly 100km from the coast in the Philippines. Tornados are also unevenly spread.
The nature of an event is initially determined by how the cause was stimulated. Volcanic eruptions occur in many different forms determined by the plate margin they are on. The eruptions on Montserrat 1995 show a strong example of the nature of a volcano at a destructive plate margin. The Soufriere Hills volcano had lay dormant for a long period of time. When the eruption did occur it was seen as explosive as it produced large volumes of acidic lava, ash, pyroclastic flows and steam.
Volcanoes are found mainly in three locations, at constructive and destructive plate margins and at hotspots. The most dangerous volcanoes occur at destructive, convergent plate margins. Here one plate subducts beneath the other, and as it descends, friction, increasing pressure, and heat from the asthenosphere and mantle melt the plate to form an acidic magma chamber. The magma at these boundaries is andesitic and rhyolitic, meaning that they have a high viscosity. Because of this the lava is resistant to flow and often forms blockages in vents.
Using the history of eruptions allows us to assess what is likely to happen in the future, for example, in the eruption of Mt. St. Helens in 1980 the volcano erupted on its side from a large bulge this left a huge crater as seen in the image. Because of this deep crater we know that neither a large debris avalanche nor a major lateral blast will like happen again. Mt. St. Helens is a very closely monitored volcano due to its previous eruptions.
A hazard is a situation that poses a level of threat to life, health, property or environment. The level of hazard posed by different volcanoes can very greatly, from a weak eruption with minimal impact that causes little damage, to a violent and life threatening explosion. Most of the sixty-plus volcanoes that erupt each year are low risk, however a combination of factors can cause a volcano to be a serious hazard. The factors causing these variations will be explained in this essay. The first factor that must be considered is the viscosity of the magma.
Then on May 18, 1980 it happened, 57 people were killed, over 7,000 animals were killed as well. The eruption destroyed entire forest, leaving only brunt tree trunks all flatten in the same direction. The amount of timber destroyed was enough to make 300,000 two-bedroom homes and the mud that traveled down the mountain destroyed about 200 houses and clogging up shipping channels in the Columbia River. The volcano itself change shape, poisonous gas and ash was released from the volcano ash poured down on 15 states within days and gas from the volcano and circled the world. It