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EARTHQUAKE CASE STUDIES (MOUNT ST. HELENS (IMPACTS (Social (57 people were…
EARTHQUAKE CASE STUDIES
MOUNT ST. HELENS
IMPACTS
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Social
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200 houses, 47 bridges, 15 miles of railways and 185 miles of highways were destroyed
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RESPONSES
Immediate
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The National Guard also issued clean water, emergency food rations and medical supplies
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Long-term
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The Toutle, Cowlitz and Comlumbia Rivers were dredged
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OVERVIEW
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At Mount St. Helens (Washington, US)
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MANAGEMENT
Prediction
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Scientists were not able to give a precise date for the eruption. They tried to predict it by measuring the frequency of earthquakes on the mountains. However, the mis-predicted the eruption by weeks (it happened too soon), which increases the vulnerability of the area
Small ash and steam eruptions during the 2 months prior to the eruption indicated increased volcanic activity.
The authorities used past eruptions to identify danger zone and evacuated residents from these areas
The experts did not predict that the eruption blast would occur on the north side of the volcano. As a result the exclusion zones set up were in the wrong place and so 90% of the people that died were outside the exclusion zone in what were thought to be safe areas.
Preparation
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However, there was political pressure from lumber companies within the area, which allowed the zoning ban to be relaxed (people were allowed in with permission, alternative routes to go in the area)
Community preparation did prevent greater loss of life. An aspect of luck was involved as the eruption occurred on a Sunday rather than a weekday, when perhaps lumbering was in full swing.
The warning system still failed to adequately inform the people in the ash fall areas about the problems they could face
NEVADO DEL RUIZ
MODIFYING THE LOSS
No preparation beforehand due to negligence of warning signs, therefore officials did not have the tools/materials to stop or delay the lahars
Officials were overwhelmed with rescuing operations and modifying the loss and did nothing to improve the modify the event itself
Two weeks after the disaster, a presidential task force named ‘Resurgir’ was created to design and direct a recovery program. Responsibilities included providing housing, food, employment, reconstruction, and urban development and verifying the identities of survivors.
US Government provided helicopters/distributed supplies/establishing field medical care and shelter facilities. The US subsequently sent additional aircraft and supplies.
Thirty other nations contributed to the rescue and assistance of survivors, this includes Japan, France, Ecuador, Iceland and the United Nations
PREPARATION
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Hazard zone map was also poorly made, with no key to indicate what each color represented, and Armero was located in the green zone (believed to indicate a safe zone)
Limited community preparation for the hazard as the government dismissed reports of volcanic eruptions
No systematic warning efforts, resulting in the residents of Armero were completely unaware of the continuing activity at Nevado del Ruiz.
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Due to the 1985 Mexico City Earthquake, limited supply for basic necessities and very few medical favilities
PREDICTION
Colombia had no equipment to monitor the volcano or geologists skilled in using monitoring equipment
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Italian scientists analyzed gas samples from the area and found unsually high carbon dioxide and sulphur dioxide levels
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Local scientists were unable to interpret the clear signs of a possible eruption (minor earthquakes, carbon dioxide levels)
OVERVIEW
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An eruption caused the ice cap on top to melt, creating a flow of lahars and pyroclastic flows
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