Homework Question on Volcanic Eruption Of Mt. St. Helens
- Choose a significant volcanic eruption (that caused significant damage and/or loss of life in some populated region of the world) from the list below.
- Cite your source(s) in the text and at the end of the document giving the full reference;
- Do not plagiarize, write in your own words.
- You will not receive credit for this question if you do not cite your source.
- Type one page on the volcano including some of the following:
- Plate tectonic setting of volcano (Is it associated with a plate boundary and if so what kind, and what plates are involved?).
- What type of eruption does it usually have?
- When was the last eruption?
- Associated hazards (pyroclastic flow, lahar etc.).
- Main causes of death (number of fatalities).
- Actions that could have reduced the losses.
- Options to choose from:
- Mt. St. Helens,
- Mt. Rainier,
- Mt. Pinatubo,
- Chaiten volcano,
- Mt. Popocatepetl,
Homework Answer on Volcanic Eruption Of Mt. St. Helens
Mt. St. Helens erupted on Sunday, May 18, 1980 at around 8:32 am PDT and caused one of the largest ever-recorded avalanches or landslides in history (Girty 4). The mountain is a volcano and part of the Cascades arc (Girty 2) that lies at the location where the small but destructive Juan de Fuca Plate is subducted by the North American plate. The mountain stands different from the other Cascade arcs that more so depict non-explosive eruptions. Mt. St. Helens underlying the Pacific Rim of fire is known to spawn pyroclastic eruptions that encompass rock ash and hot gases.
Small earthquakes were observed and experienced before the explosion. However, in the lateral eruption, a massive wave of hot rock ash and an avalanche of debris spewed 12 miles followed by the pyroclastic flow at speeds of about 200 kilometers an hour (BBC). The massive damage on vegetation, animals, and property makes it the most devastating eruptions in the U.S and Pacific Rim of fire. The lateral flow of debris destroyed forests and logging camps and the ash blocked waterways, such as the Toutle River, and hence, flooding and damaging the fishing sites (Nash 572).
Lahars containing coarse material were matured from the hot pyroclastic flow melting the ice and snow flowing down the muddy rivers and valleys (Girty 8). They initially started at high speeds and progressed to become slow as they moved through the valleys to become mudflows. Human life was not spared as the number of deaths stood at 57 individuals, mostly dying from asphyxiation (Gray). Millions of properties were destroyed with Girty quoting the total loss at about $2.74 billion (Girty 9).