Geography A-Level - Physical - Volcanic Hazards
- Created by: Noah_S
- Created on: 24-05-21 14:43
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- Volcanic Hazards
- Case Study - Monserrat
- Pre-Disaster
- Small eruptions began in 1995, main eruption in 1997
- Monserrat above a destructive plate margin (North American + Caribbean Plate)
- Impacts
- £1 Billion worth in damage from Primary Impacts (Economic)
- Tourism stayed away, disrupting the economy (Economic)
- Tourism has started to increase due to people wanting to see the volcano
- 19 people died + 8000 of the 12000 inhabitants left. (Social)
- Plymouth buried under 12m of mud and ash + Farmland destroyed (Environment)
- Volcanic ash has improved the soil fertility around the volcano
- Responses
- People evacuated from the south to safe areas in the north (Short Term)
- UK provided £17 million in emergency aid (Short Term)
- Exclusion zone on the south of the island while the volcano is intermittently active (Long Term)
- £41 million in long-term aid to build infrastructure + Montserrat Volcano Observatory to monitor (Long Term)
- Pre-Disaster
- Case Study - Mt Pinatubo
- Impacts
- Ash & Pyroclastic Flows changed the topography (Environment)
- Super Typhoon Yunga landfalls during eruption, creating Lahars (Environment)
- Clark US Airbase destroyed (Economic)
- Pre-Disaster
- Minor steam eruptions gave warnings for Eruption
- Confirmed when SO2 levels raised 10x between April-May
- June 12th & 15th had major eruptions, sending ash as far as 400 miles
- Pyroclastic flows devastated an area of 40 sqr miles
- Minor steam eruptions gave warnings for Eruption
- Responses
- General Evacuation called in May, 60,000 evacuated (Short Term)
- Ash + SO2 caused global cooling for 3 years - 1992 average temperature was down 0.5-1*C (Long Term)
- Chlorine compounds released destroys Ozone in atmosphere (Long Term)
- Impacts
- General Theory
- Differences
- Dissolved Gas
- More gases means the magma is more fluid
- Temperature
- Higher temperatures = Lower density magma
- Chemistry
- High Silica = More viscosity
- Dissolved Gas
- Distribution
- Rift Valleys (East Africa)
- Crust is thin as plates move apart
- Basic Magma, Frequent & Gentle Eruptions
- Subduction Zones (Carribean)
- Melting at Benioff Zone means plutons rise
- Acid Magma, Infrequent & Explosive Eurptions
- Hot Spots (Hawaii)
- Magma breaks through crust from heating
- Basic Magma, Frequent & Gentle Eurptions
- Oceanic Ridges (Iceland)
- Lots of volcanoes from sea floor spreading
- Basic Magma, Frequent & Gentle Eruptions
- Rift Valleys (East Africa)
- Impacts
- Secondary
- Lahars - Travels at 100kph for as much as 300km
- Acidic Rain - Sulphur ejected by the volcano creates Sulfuric Acid
- Climate Change - Material reduces temperatures
- Primary
- Tephra - Ranging from Ash (< 2mm) to Volcanic Bombs (>64mm)
- Pyroclastic Flows - 800*C+ and travels at 700kph at the ground
- Secondary
- Differences
- Case Study - Monserrat
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