Mount St Helens Essay
Being so close to an active volcano poses many risks to communities. Even though Mount St. Helens erupted over 30 years ago we know that it is still an active volcano. Future eruptions can kill and injure entire communities. Since the eruption in May of 1980 of Mount St. Helens, geologists have come to a better understanding of both the mechanics of volcanoes and the dangers they present to the environment and communities. Did you know that volcanic ash is actually small glass particles? Or that the majority of volcanoes are submarine? Understanding some of these different facts can help us to understand the earth's volcanic processes. Volcanoes erupt different materials and those can become different after cooling. Things like lava, gases
…show more content…
and tephra (ash, bombs) can spew out and not always in gigantic explosions. The type and amount of the material produced depends on the composition of magma. If the magma is fluid it can flow rapidly down the mountainside (A'a), while lava that is stickier moves much slower but can produce an explosive eruption (Pahoehoe). The gases released from volcanic eruptions, consists mostly of water vapor but also include carbon dioxide, sulfur dioxide and other gases. Tephra, also known as pyroclastic material, is made of rock fragments coming from either solidified pieces of magma or parts of the pre-existing rock torn from the volcano. The dense pyroclastic material; which is fresh magma, pumice or volcanic ash travels along the ground at fast speeds during explosive eruptions. Less dense material, also containing bits of fresh magma and ash moves even faster and can rise thousands of feet in the air. Another fact about volcanoes is that we can make assumptions about them according to the kind of tectonic boundary they reside on. Divergent boundaries generally produce non-explosive eruptions, where magma is filling the separation of the plates or feeding lava flows. Also divergent boundaries create rift valleys in the oceans, and that can lead to submarine volcanoes. In convergent boundaries, one plate is subducted under another. The subducted plate will eventually melt into a magma plume and slowly rise to the surface of the earth. These plumes are often the start of strato-composite volcanoes like Mount St. Helens. Transform boundaries are more known for being earthquake zones but places like the Long Valley Caldera have magma activity and sit along a transform boundary. Volcanoes present a variety of hazards to the communities surrounding them.
Explosive volcanoes present the most danger from pyroclastic flows, ash falls, lahars, landslides, tsunamis and gas emissions. Pyroclastic flows consist of a mixture of hot gas, ash and rock that flow rapidly over the ground. The dense the material is restricted to valley bottoms, while less dense material can travel over hills and ridges. The flows kill by impact, searing and suffocation. Ash falls are a volcanic dust that can travel hundreds and thousands of meters in the air. Major eruptions can change weather patterns when large quantities of ash are distributed into the air. The dust particles absorb sunlight and can affect global weather changes for many years. When ash becomes wet it is heavy and abrasive, which can immerse people and buildings destroying them. People cannot breathe ash; neither can jet engines causing many deaths. Lahars are volcanically generated mudflows produced by the mixing of ash with rain or melting snow, which is present on many volcanoes. Lahars travel in the valley bottoms much like pyroclastic flows and kill by suffocation or flooding. Tsunamis can be extremely dangerous also. Tsunamis are giant waves generated either by an earthquake or entire flank of a volcano crashing into to the water. Many tsunamis occur without notice and many die from flooding on the coastline. Non-explosive eruptions can also present dangers. Lava flows, which generally move slow mainly
cause property damage by setting fire to buildings or forested areas. Volcanoes either active or extinct have very unstable slopes that create landslides or avalanches. The landslides are often triggered by earthquakes, weather changes and minor eruptions kill by impact, suffocation and flooding. Many communities have been formed in the shadow of volcanoes, which present so many dangers if public authorities and governments don't take action to prevent many injuries and death. In 1902, Mount Pelee a volcano on the island of Martinique erupted killing 30,000 people in the city of St. Pierre. Prior to the major eruption, the volcano gave many warnings of an approaching eruption, but because of political reasons the government of Martinique discouraged and prohibited the evacuation of their people.
and tephra (ash, bombs) can spew out and not always in gigantic explosions. The type and amount of the material produced depends on the composition of magma. If the magma is fluid it can flow rapidly down the mountainside (A'a), while lava that is stickier moves much slower but can produce an explosive eruption (Pahoehoe). The gases released from volcanic eruptions, consists mostly of water vapor but also include carbon dioxide, sulfur dioxide and other gases. Tephra, also known as pyroclastic material, is made of rock fragments coming from either solidified pieces of magma or parts of the pre-existing rock torn from the volcano. The dense pyroclastic material; which is fresh magma, pumice or volcanic ash travels along the ground at fast speeds during explosive eruptions. Less dense material, also containing bits of fresh magma and ash moves even faster and can rise thousands of feet in the air. Another fact about volcanoes is that we can make assumptions about them according to the kind of tectonic boundary they reside on. Divergent boundaries generally produce non-explosive eruptions, where magma is filling the separation of the plates or feeding lava flows. Also divergent boundaries create rift valleys in the oceans, and that can lead to submarine volcanoes. In convergent boundaries, one plate is subducted under another. The subducted plate will eventually melt into a magma plume and slowly rise to the surface of the earth. These plumes are often the start of strato-composite volcanoes like Mount St. Helens. Transform boundaries are more known for being earthquake zones but places like the Long Valley Caldera have magma activity and sit along a transform boundary. Volcanoes present a variety of hazards to the communities surrounding them.
Explosive volcanoes present the most danger from pyroclastic flows, ash falls, lahars, landslides, tsunamis and gas emissions. Pyroclastic flows consist of a mixture of hot gas, ash and rock that flow rapidly over the ground. The dense the material is restricted to valley bottoms, while less dense material can travel over hills and ridges. The flows kill by impact, searing and suffocation. Ash falls are a volcanic dust that can travel hundreds and thousands of meters in the air. Major eruptions can change weather patterns when large quantities of ash are distributed into the air. The dust particles absorb sunlight and can affect global weather changes for many years. When ash becomes wet it is heavy and abrasive, which can immerse people and buildings destroying them. People cannot breathe ash; neither can jet engines causing many deaths. Lahars are volcanically generated mudflows produced by the mixing of ash with rain or melting snow, which is present on many volcanoes. Lahars travel in the valley bottoms much like pyroclastic flows and kill by suffocation or flooding. Tsunamis can be extremely dangerous also. Tsunamis are giant waves generated either by an earthquake or entire flank of a volcano crashing into to the water. Many tsunamis occur without notice and many die from flooding on the coastline. Non-explosive eruptions can also present dangers. Lava flows, which generally move slow mainly
cause property damage by setting fire to buildings or forested areas. Volcanoes either active or extinct have very unstable slopes that create landslides or avalanches. The landslides are often triggered by earthquakes, weather changes and minor eruptions kill by impact, suffocation and flooding. Many communities have been formed in the shadow of volcanoes, which present so many dangers if public authorities and governments don't take action to prevent many injuries and death. In 1902, Mount Pelee a volcano on the island of Martinique erupted killing 30,000 people in the city of St. Pierre. Prior to the major eruption, the volcano gave many warnings of an approaching eruption, but because of political reasons the government of Martinique discouraged and prohibited the evacuation of their people.