Mount Ontake Japan (volcanic) Flashcards
(12 cards)
Where is Mount Ontake located?
Central Japan on the boundary between Nagano and Gifu
What type of plate is Ontake on?
Destructive plate
What formed Mount Ontake?
The pacific plate subducting beneath the Eurasian plate
What type of volcano is Mount Ontake?
Stratovolcano
What type of eruption was it?
Phreatic eruption driven by steam - no magma involved
When did the eruption occur?
27th September 2014
Why was it so deadly
pressurised steam ejected rock, ash and toxic gas
ash rose over 7km into atmosphere
Pyroclastic surges and lahars generated on slopes
ash blocked out sun, asphyxiating hikers at peak
silica rich magma trapped gas, leading to pyroclastic flows
Social Impacts
57 died and 40 injured
ash inhalation led to respiratory diseases
some had ptsd
Economic impacts
Local economy relied heavily on pilgrims to Ontake shrine
autumn climbing season cancelled and popular routes closed for 4 years
large clean up costs due to large amount of ash which covered up to half a metre
ash contaminated local water supplies and crops near the volcano
aircrafts stopped due to volcanic ash
$134 million in damages
Environmental Impacts
Vegetation damaged around volcano
ash polluted rivers and streams, increasing acidity temporarily
ecosystems and habitats displaced
Lahars formed during heavy rains after the eruption, leading to slope erosion
short-term response
1,100 Japan’s defense forces, firefighters and police deployed quickly
rescue helicopters could not land as ash mixed with rainwater, preventing access for emergency services
80 climbers hiked to provide aid to 40 survivors
air space around volcano closed due to ash in engines
Long term responses
Japan Meteorological Agency installed tiltmeters, seismometers and gas sensors
Volcanic hazard zones reassessed and evacuation plans revised
local hiking groups and tourists now required to check volcano warnings
Japanese gov reviewed emergency response law to improve inter-agency coordination for sudden phreatic eruptions
