Case Studies - Hazards
Volcanoes
Montserrat
Date: Active since 1995, major eruption on 25 June 1997
VEI: 3
Cause of eruption:Montserrat lies on a destructive plate margin meaning the volcano
lies at the boundary between an oceanic and continental plate.
Hazards Caused: Large pyroclastic flows, ash venting and explosive eruptions
Impacts: 19 deaths in 1997, ⅔ of the island were covered in ash, 50% of population
evacuated to the North, only airport was closed, Plymouth (capital) abandoned,
destroyed tourism and farming due to acid rain, population fell from 11,000 people to
4,000 people
Response: Montserrat volcano observatory was set up to monitor the volcano and
predict any future eruptions, a risk map of the island was created, £41 million donated
by the British government, riots broke out.
Other: predictions ignored prior to eruption, education help save lives
Example of: Overseas AC territory
Sakurajima
Date: Near daily eruptions since 1955
VEI: N/A
Cause of eruption: Sakurajima is a modern active vent of a caldera volcano.
Hazards Caused: Volcanic ash
Impacts: Attracts tourist to the area
Other: Mitigated using sensors, specialised cleaning teams and variable restricted
access in the area.
Example of: Mitigation of daily eruptions
Mount St Helens
Date: 18th May 1980
VEI: 4
Cause of eruption: An explosive dacite volcano with a complex magmatic system.
The volcano started forming about 275,000 years ago and has been the most active
volcano in the Cascade Range during the Holocene.
Hazards Caused: Lateral blast, ashfall, lahars, flooding, communities buried in 4
inches of ash, landslides
Impacts: 57 people died, All plants and animals killed within 25km radius, $100
million of damage, PTSD of residents, flights cancelled. Thousands of trees wiped out
Other: Series of small earthquakes alerted people of reawakening of St Helens and
observation post setup, exclusion zone created, tourism increased
Example of: AC, large eruption, few deaths, mitigated.
, Pinatubo
Date: 15th June 1991
VEI: 6
Cause of eruption: 7.8 magnitude earthquake 100km away reawakened volcano
Hazards Caused: pyroclastic flows, 1ft of ash, 10 mile wall of pyroclastic flow, sever
mudflows and lahars
Impacts: everyone with 12km evacuated, 128,000 evacuated, death toll under 500,
global temps dropped 0.5 celsius, thunderstorms, closure of clark air base.
Other: 4 stage alert system and early monitoring from USGS saved lives.
Example of: well mitigated, geopolitical support by USA
Big E
Date: 20th March 2010
VEI: 2
Cause of eruption: Iceland being on a plate boundary, mid-atlantic ridge, under a
glacier, strong jetstream,
Hazards Caused: fragments of volcanic glass and ash spread across europe in the
jetstream, jokulhaups, toxic gases released
Impacts: no deaths, $2.6 billion of GDP lost in Europe, Kenya lost money as unable to
fly goods to Europe, benefited channel tunnel and trains. $2 billion airline industry
Other: cut holes in roads to prevent damage, FutureVolc to mitigate against future
similar hazards.
Example of: Impact of global systems, AC, unable to mitigate
Nevado del Ruiz
Date: 13th November 1985
VEI: 3
Cause of eruption: fed by magma generated above the boundary between the
subducting Nazca and overriding South American tectonic plates.
Hazards Caused: An explosive eruption on 13 November melted ice and snow in the
summit area, generating lahars that flowed tens of kilometres down flank river valleys
Impacts: 150,000 animals died, 23,000 people died, 3400 hectares of farmland lost,
cost colombian economy $7.7 billion (20% of GDP)
Other: vaccines to stop spread of disease, hazard maps created, public education
programs created.
Example of: no mitigation, developing country.
Nyiragongo (Congo)
Date: 22 May 2021
VEI: n/a
Cause of eruption: effusive eruption and rapidly filling lava lake.
Hazards Caused: lava flows, aftershocks
Impacts: 250 dead, 1,000 homes lost, 17 villages destroyed
Volcanoes
Montserrat
Date: Active since 1995, major eruption on 25 June 1997
VEI: 3
Cause of eruption:Montserrat lies on a destructive plate margin meaning the volcano
lies at the boundary between an oceanic and continental plate.
Hazards Caused: Large pyroclastic flows, ash venting and explosive eruptions
Impacts: 19 deaths in 1997, ⅔ of the island were covered in ash, 50% of population
evacuated to the North, only airport was closed, Plymouth (capital) abandoned,
destroyed tourism and farming due to acid rain, population fell from 11,000 people to
4,000 people
Response: Montserrat volcano observatory was set up to monitor the volcano and
predict any future eruptions, a risk map of the island was created, £41 million donated
by the British government, riots broke out.
Other: predictions ignored prior to eruption, education help save lives
Example of: Overseas AC territory
Sakurajima
Date: Near daily eruptions since 1955
VEI: N/A
Cause of eruption: Sakurajima is a modern active vent of a caldera volcano.
Hazards Caused: Volcanic ash
Impacts: Attracts tourist to the area
Other: Mitigated using sensors, specialised cleaning teams and variable restricted
access in the area.
Example of: Mitigation of daily eruptions
Mount St Helens
Date: 18th May 1980
VEI: 4
Cause of eruption: An explosive dacite volcano with a complex magmatic system.
The volcano started forming about 275,000 years ago and has been the most active
volcano in the Cascade Range during the Holocene.
Hazards Caused: Lateral blast, ashfall, lahars, flooding, communities buried in 4
inches of ash, landslides
Impacts: 57 people died, All plants and animals killed within 25km radius, $100
million of damage, PTSD of residents, flights cancelled. Thousands of trees wiped out
Other: Series of small earthquakes alerted people of reawakening of St Helens and
observation post setup, exclusion zone created, tourism increased
Example of: AC, large eruption, few deaths, mitigated.
, Pinatubo
Date: 15th June 1991
VEI: 6
Cause of eruption: 7.8 magnitude earthquake 100km away reawakened volcano
Hazards Caused: pyroclastic flows, 1ft of ash, 10 mile wall of pyroclastic flow, sever
mudflows and lahars
Impacts: everyone with 12km evacuated, 128,000 evacuated, death toll under 500,
global temps dropped 0.5 celsius, thunderstorms, closure of clark air base.
Other: 4 stage alert system and early monitoring from USGS saved lives.
Example of: well mitigated, geopolitical support by USA
Big E
Date: 20th March 2010
VEI: 2
Cause of eruption: Iceland being on a plate boundary, mid-atlantic ridge, under a
glacier, strong jetstream,
Hazards Caused: fragments of volcanic glass and ash spread across europe in the
jetstream, jokulhaups, toxic gases released
Impacts: no deaths, $2.6 billion of GDP lost in Europe, Kenya lost money as unable to
fly goods to Europe, benefited channel tunnel and trains. $2 billion airline industry
Other: cut holes in roads to prevent damage, FutureVolc to mitigate against future
similar hazards.
Example of: Impact of global systems, AC, unable to mitigate
Nevado del Ruiz
Date: 13th November 1985
VEI: 3
Cause of eruption: fed by magma generated above the boundary between the
subducting Nazca and overriding South American tectonic plates.
Hazards Caused: An explosive eruption on 13 November melted ice and snow in the
summit area, generating lahars that flowed tens of kilometres down flank river valleys
Impacts: 150,000 animals died, 23,000 people died, 3400 hectares of farmland lost,
cost colombian economy $7.7 billion (20% of GDP)
Other: vaccines to stop spread of disease, hazard maps created, public education
programs created.
Example of: no mitigation, developing country.
Nyiragongo (Congo)
Date: 22 May 2021
VEI: n/a
Cause of eruption: effusive eruption and rapidly filling lava lake.
Hazards Caused: lava flows, aftershocks
Impacts: 250 dead, 1,000 homes lost, 17 villages destroyed
