Tectonic Hazards Revision

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  • Created by: Théa
  • Created on: 10-06-13 21:50

CASE STUDY: Nevado del Ruiz, Columbia

Location: Columbia, Andes Mountains

When: 13th November 1985

Cost of Damage: US$ 7.7 billion

Death Toll: 23,000

Injured: 5,000

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CASE STUDY: Nevado del Ruiz, Columbia

Causes:

-The volcano lies on a DESTRUCTIVE plate boundary.

-Seismic activity was measuring 1 year before the eruption

-The ice cap of the volcano was mixed, creating mud flows / LAHARS. 

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CASE STUDY: Nevado del Ruiz, Columbia

Impacts:

Primary:

-People died from the LAHARS and many were injured

-85% of the town of Armero was wiped out and covered in the mud flows

-Roads and bridges were destroyed

-5000 homes were destroyed

-Livesotck was killed

Secondary:

-10,000 were homeless

-Water supply was damaged, causing health problems and disease began to spread quickly, plus it generally had other social, cultural and phychological impacts.

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CASE STUDY: Nevado del Ruiz, Columbia

Reasons for the severity of the impacts:

Physical:

-The mud couldn't support any form of vehicle for the rescues

-Torrential rains and the mountains made access difficult

-The eruption occured at night time

Human:

-An evacuation was called off

-There was a shortage of helicopters, which were the only apporpriate vehicles for rescue

-Emergency services were late to respond, setting up temporary hospitals several days after the eruption.

-Plus, aid was difficult to be distributed, and unnecessary mass vaccinations were given to people 

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How could the impacts have been reduced/how were t

-They moved the critically ill to ther places, in order to have space, in case another eruption occured.

-They could have carried on with the evacuation of locals / they could improve their warning systems

-They could create a prparedness plan of action

-They could improve their infrastructure

-They could also make better politcal relationships with MEDCs for aid

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CASE STUDY: Mount St Helens, USA

-Mount St Helens is located on the 'Ring of Fire'

-Mt St Helens is in the state of Washington, near Portland and Seattle

-The two plates invloved in the volcano are:

      -Juan de Fuca Plate (Oceanic)

      -North American Plate (Continental)

When: 18th May 1980  8:32am

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CASE STUDY: Mount St Helens, USA

Before/Background:

-Dormant

-Surrounded by lakes, forests, streams

-Popular with campers and tourists

-Was active many times before and is also known as 'Fire Mountain'

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CASE STUDY: Mount St Helens, USA

Causes:

-Earthquakes, which started in March

-People began to see ash and gas, and scientists began coming to study and survey the volcano

-Crater grew and grew (April)

-The top of the mountain and ashes and ice fell from the volcano

-When it erupted, there had been snow and ice at the top, so this melted

-It was caused by an earthquake of 5.1 on the Richter Scale

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CASE STUDY: Mount St Helens, USA

Effects:

Primary:

-Ash came down in pyroclastic flows, at 100mph, also causing landslides

-Then this caused mud flows

-57 people died

-40,000 acres of wood were destroyed

-The blast zone was 230 miles

Secondary:

-Water and rivers picked up debris, eventually clogging up the Columbia river

-Ash got blown with strong north-eaterly winds, covering towns far from the eruption. This meant that water became the consistency of cement.

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CASE STUDY: Mount St Helens, USA

Response:

Short-term:

-People were urged to leave in April and many did

-Roads and bridges were repaired quickly

-People were rehoused

Long-term:

-There was an Envirionmental Analysis to recuperate the land and forests

-USGs is continually surveying the crater of the volcano

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CASE STUDY: Comparision

Causes:

-Seismic activity

-Pyroclastic flows and mud flows

-Snow and ice present when eruption occured

Impacts:

-Water and rivers affected

-Some roads, bridges and homes were destroyed

Response:

-People were relocated and rehoused

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CASE STUDY: Comparision

Differences:

-Many more people died when Nevado del Ruiz erupted

-Many more homes, properties and livelihoods were detroyed in Armero, than in the surroundings of Mt. St Helens

-The mud flows were more intense in Nevado del Ruiz, eruption, whilst Mt. St Helens eruption had much more ash, which affected a wide range of people, across several states

-Response for the Mt. St Helens eruption was quicker and easier

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