9) Montserrat Volcanic hazards

Montserrat

Caribbean islands, 1995-1998
(didn't stop erupting until 2018)
- British overseas territory
- island arc formed where north American tectonic plate subduct beneath Caribbean plate forming composite stratovolcanoes

DESTRUCTIVE PLATE MARGIN
(South American plate subducts under Caribbean plate)

Earthquakes all along Benioff zone, magnitude of 7

- islands formed by repeated violent eruptions
- lava domes created as a result of viscous silica rich lava building up at vent, becoming too heavy and causing collapse of dome
= pyroclastic + andesitic lava

Warning Signs

steam forced from vents opened in tops + sides of volcano, indicating magma was forcing way through rocks below
(PHREATIC ERUPTION)

- dark clouds, rumbling
- microquakes and tremors
- rock falls and tephra ejected

Dome forming

incandescent, dome at top of volcano is made of thick viscous molten material (acidic lava) which doesn't flow and builds up around top

large mass o material on top of volcano is very hot and under a lot of pressured, e=being built up and deformed from inside

acidic lava = rich in silica and has low melting point so remain a liquid, cools and solidifies quickly

most likely to appear at DESTRUCTIVE

first lava started to appear 4 months after vents and opened and dome grew (1995)

Hazards

collapsing dome, very hot inside + unstable

rock falls began April 1996

pyroclastic flows, avalanche of hot material

explosions from collapse

magmatic eruptions + ash clouds

lahars from heavy rain + tephra

fires from pyroclastic

Primary Effects: social

19 killed by pyroclastic flow

7 injured, burn and inhalation injuries

2/3rds of island covered in 12m ash
- couldn't get aid to people as roads impassable

20 villages destroyed by pyroclastic flows
- 2/3rds houses destroyed

ash made it difficult to breath
- respiratory and cardiovascular problems

pyroclastic flows forced people to be evacuated
- 50% of pop. evacuated to north in temporary shelters

Primary Effects: economic

biggest impacts = in capital (Plymouth)
- home to around 4,500 people
- housed main port + gov. buildings and many businesses
- buried by debris and lava from volcano above it

capital completely destroyed by:
ash fallout, rain erosion, pyroclastic flow, all causing the deposits to build up over time

business in Plymouth eliminated

population demographics changed drastically, working age of pop. migrated elsewhere for work
- only very young and very old left
- by 2000, pop. fell to less than 2500 (fell by 25%)

had to be funded by British economy, receiving around £25 million a year

airport destroyed by pyroclastic flow

Primary Effects: environmental

large areas of vegetation lost due to pyroclastic flows, lahars, ash fallout

most of agricultural land was close to volcano due to fertile land, destroyed due to immediate effects (pyroclastic, ash, rockfalls)

forest fires caused by pyroclastic flows

rainforest habitats and much vegetation destroyed by pyroclastic flow

Primary Effects: political

government building had to be relocated quickly

community centre that was housing prisoners was in the exclusion zone and evacuation zone, had to be relocated

Secondary Effects: social

many houses in exclusion zone and people only given a few hours to gather possessions

divided communities and families, emotional impact on country

appalling conditions in evacuation camps + shelters

clogged engines and machinery from prevailing winds + ash fallout
- travel disrupted

overcrowded, poor sanitation, not enough in shelters

weight of thick ash deposits caused houses to collapse

tsunamis caused by pyroclastic flows, destroyed farmland, schools, hospitals

Secondary Effects: economic

airport + seaport in exclusion zone, access for tourism became difficult

agricultural lands no longer workable
- 300 full time farmers lost ability to grow crops

unemployment increased from 7% to 50%

many airports around the world closed due to ash

3/4 of infrastructure, farming + vegetation destroyed

Secondary Effects: environmental

pyroclastic flows destroyed marine habitats, coral reefs covered in ash
- unlikely to ever recover

rainforest habits destroyed by pyroclastic + lava flows
- affected critically endangered mountain chicken frog as destroyed much of habitat

ash made water frogs bathe in very acidic, causes problems to skin/body

ash fallout reduced insect abundance, less food supplies

volcano released sulphur dioxide + hydrogen sulphide, caused acid rain
- poisoned plants
- reduced growth of/killed plants
- less food available

scarce resources, more competition between animals
- farm animals released during eruption, bred uncontrollably so less food available, eliminated

Secondary Effects: political

enrolment in all schools dropped from 2670 in 1995 to 620 in 1998

pop. decreased from 13,000 to 5,000

Plymouth destroyed
- contained all main services (hospitals, schools, gov. buildings)

short term responses

airports repaired hastily
- short runways meant only small planes could land

NGOs (red cross) set up temporary schools + provided medical support + food
- evacuation centres in churches + community centres

warning systems set up to alert inhabitants
- sirens, speaker systems, media

troops from USA + British navy came to aid evacuation process

£17 million of UK aid paid for temporary buildings + water purification systems
- redevelopment + compensation

atonement of capital city
- large scale evacuation by British navy
- increase in umemployment due to collapse of tourist industry

long term responses

Belham valley golf course, destroyed by lahars, covered in high quality sand + gravel for buildings + mining operations
- created 30 new jobs

potential geothermal power supplies using underground steam
- decrease electricity cost + heating significantly

rebuilding cultures that were lost due to out migration to uk
- "Montserrat idol", music + traditions
- many people started to move back

3 year development programme for houses, schools, medical services, etc.
- uk funded

tourism industry rebuild
- transform are around bay/port into a resort hotel
- 20 luxury villas, spa, boat centre
- private investment will increase local business

fertile land from ash used for agricultural services + farming, local jobs

conserving and establishing coral reefs
- reef balls (concrete structures w/ coral) = artificial reefs
- increase in fish pop.
- provides opportunities for divers, work + tourism

Plymouth reopened for tourism, guided tours around volcano, top 25 new trips of 2010 by National Geographic Adventure Magazine

Construction of new, larger airport
- bigger runway so that passenger planes can land

UK financial aid = exceeded £420 million since 1995

exclusion zone set up in the volcanic regions
- categorising highly hazardous areas as "A, B or C" for evacuation planning + hazard zoning

Monitoring + communication stations to study any significant changes to volcano 24h/day
- Montserrat Volcano Observatory
(succesful in predicting 1997 eruptions)

hazard management cycle application

Preparedness

Response:
- Red Cross, emergency shelter, troops
- £17 million
- small airport for aid
- evacuation, out migration + residency
- gov buildings relocated

Recovery:
- tourism industry
- conserving reefs
- 30 new jobs
- 3year development plan
- £420 million in aid

Mitigation
- exclusion zones
- MVO