Tectonic Hazards Revision
- 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
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.
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.
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
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
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
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'
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
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.
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
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
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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