Tectonics Flashcards
1
Q
Context of Montserrat Volcano?
A
- Soufriere Hills Volcano erupted in June 1997
- composite volcano along destructive margin between NA and Caribbean plates
- EQ’s, lahars and small erupions began two years before the main event
- pyroclastic flows started just before the eruption
- 4.5 million m^3 of material was released over 20 minutes
- pyclastic flows came within 50m of the airport
- subsequent eruptions in following months with airport destroyed in September
2
Q
Economic Impacts of Montserrat Eruption? (negative then positive)
A
Negative:
- loss in property and investment value totalled £1bn
- over 20 villages and 2/3 of homes on the island destroyed
- loss of tourism and business
- schools, hospitals, the airport and port destroyed
Positive:
- tourism to volcano now picking up due to renewed interest
3
Q
Social Impacts of Montserrat Eruption? (negative then positive)
A
Negative:
- 19 dead and 7 injured
- hundreds lost their homes
- fire destroyed many more buildings than the eruption including many govt buildings (police stations, etc.)
- 2/3 of the population have left since (1/3 to the UK), population decline has decimated the local economy
No positives
4
Q
Environmental Impacts of Montserrat Eruption? (negative then positive)
A
Negative:
- large areas covered with volcanic material, Plymouth (the capital) covered by 12m of ash and mud
- vegetation and farmland destroyed
Positive:
- volcanic ash has improved soil fertility
5
Q
Responses to Montserrat Eruption? (short then long term)
A
Short-term:
- people evacuated from the South to safe areas in the North, starting two years before the event
- shelters built to house evacuees
- temp. infrastructure build e.g. roads and electricity distribution
- UK provided $17mil in short-term emergency aid
- local emergency services started search and rescue operations
Long-term:
- risk map created and exclusion zone (south of island) created
- UK provided £41mil in long-term aid to rebuild infrastructure and houses
- Montserrat Volcano Observatory established
6
Q
Management of the Montserrat Eruption?
A
- scientists studied the volcano in the 80’s but little attention was paid to their findings
- no disaster management plan meaning responses were far too slow
- in the 90’s, key infrastructure was built in high risk areas, further hampering the response when it was destroyed
7
Q
Context of Mt. St. Helens Eruption?
A
- Mt. St Helens erupted in May 1980
- part of the Cascade Mountains of Washington
- on a destructive margin between the Juan De Fuca and NA plates
- composite volcano
- from March 1980: small EQ’s, a bulge appeared, ash and steam released
- on the day, a large 5.1 EQ following by the eruption
- 600km^2 fan-shaped area north of the volcano was affected - where almost all vegetation and buildings were destroyed
- pyroclastic flows, lahars and floods caused immense damage
- 540 million tonnes of ash distributed over 57000km^2
8
Q
Economic Impacts of Mt. St Helens Eruption? (negative then positive)
A
Negative:
- total costs to businesses and individuals: $1.1bn
- over 200 homes and cabins destroyed and many more damaged
- airports closed for two weeks - 1000 flights cancelled
- vast amounts had to be spent clearing ash from routeways, in Yakima (135km from volcano) alone, $2.2mil was spent
- 27 bridges, 25km of railways and around 300km of roads were destroyed
- river traffic and shipping disrupted - 30 ships stranded due to sediment in rivers
- timer industry badly affected
No positives
9
Q
Social Impacts of Mt. St Helens Eruption? (negative then positive)
A
Negative:
- 57 killed, mostly due to respiratory issues
- hundreds lost their homes
- unemployment briefly rose 10x but quickly normalised
- social and recreational facilities destroyed
- emotional stress caused
No positives
10
Q
Environmental Impacts of Mt. St Helens Eruption? (negative then positive)
A
Negative:
- 240km^2 of forest destroyed
- 7000 big game animals and many thousand birds and small animals killed
- 12 million young salmon killed
- sediment dumped in Spirit Lake raised water level by over 60m
- water quality temporarily reduced
Positive:
- improved soil fertility, but very few farmers in area
11
Q
Responses to Mt. St Helens Eruption?
A
- coordinated by FEMA, assisted by US military
Short Term:
- face masks distributed to prevent ash inhalation
- emergency shelters set up
Long Term:
- ash clean-up operations - 900,000 tonnes of ash cleared off infrastructure
- shipping channels cleared of sediment and new channels cut to restore shipping to normal
- 45,0000 aces of land replanted
- water supplies monitored to ensure they were not contaminated
12
Q
Management of Mt. St Helens Eruption?
A
- in March, USGS set-up a 42-hour monitoring system (seismic data, bulge growth, ground temp, gas emissions)
- reports issued daily
- issued warnings to locals and designated hazardous zones
- in March, exclusion zone created and 2000 evacuated
- However, could still not accurately predict when the eruption would occur, even on the day
13
Q
Context of the L’Aquila Earthquake?
A
- occurred in April 2009
- L’Aquila is a city in central Italy with a population of 70,000
- major fault lines run underneath L’Aquila
- close to the destructive margin between Eurasian and African plates
- 6.3 on the Richter scale
- depth of 5km, epicenter near L’Aquila
- several aftershocks up to 5 on the Richter scale
14
Q
Economics Impacts of L’Aquila Earthquake?
A
- costed $15bn in total
- thousands of building destroyed including hospitals and the cathedral
- bridge near Fossa collapsed and several water pipes were broken
- fires caused further damage to collapsed buildings
15
Q
Social Impacts of L’Aquila Earthquake?
A
- 300 deaths, mostly by collapsing buildings
- 1500 injured
- 70,000 made homeless
- aftershocks hampered immediate response
- people moved away in search of work
16
Q
Environmental Impacts of L’Aquila Earthquake?
A
- 1000km^2 affected by surface ruptures, rockfalls and landslides
- broken water pipe near Paganica caused a landslide
- habitats disrupted
17
Q
Responses to L’Aquila Earthquake?
A
- camps setup for homeless with water, food and medical supplies
- ambulances, fire engines and army sent in to help rescue
- cranes and diggers used to remove rubble
- international teams with rescue dogs sent in
- 12,000 rescue and support workers
- mortgage payments and utility bills were suspended
- new town build to replace L’Aquila with 4500 new buildings housing 12,000 in 6 months
18
Q
Management of the L’Aquila Earthquake?
A
- there were some management strategies in place but they were not very effective
- strict building regs. for new buildings to withstand EQs, but some were still poorly built and collapsed e.g. San Salvatore Hospital
- some monitoring was in place - but it is very difficult to predict EQs, this may have caused locals to be complacent
- Civil Protection Department trained to help with rescue operations
19
Q
Context of the Kashmir Earthquake?
A
- occurred on 8/10/2005
- Kashmir is in Northern Pakistan on the destructive margin between Indian and Eurasian plates
- 7.6 on the Richter scale
- 16 mile depth with epicenter close to Muzafrabad
- caused by plate movement creating a 75km fault
- 30,000km^2 area damaged
- almost 1000 aftershocks up to magnitude 4
