Mount Ontake Eruption Flashcards
Deaths
63; 31 near summit, 6 classed as missing
When did it happen
27th September 2014
what type of eruption was it
phreatic
what is a phreatic eruption
Subsurface or surface water is heated and converted to steam by hot magma underground, builds pressure due to thermal expansion which creates an explosion
VEI
3
Common cause of injury
injuries from tephra
What hazards were produced?
Ash falls, pyroclastic flows, tephra, lahars/ mudflows.
Why was the eruption not detected
It didn’t produce much seismic activity beforehand due to it being phreatic. 5 families of victims attempted to sue the Japanese government saying they should have raised the warning level.
What is a possibility why so many people died
Lack of warning and close proximity to climbers.
The volcano was known as safe and easy to climb - popular with tourists.
Eruption happened around lunchtime -people at the summit eating lunch
How far did the pyroclastic flow travel
2.5km along the valley at average speed of 32kmh
How many people were trapped on the slopes
250 people were trapped due to the pyroclastic flows
How much ash was produced
40-50cm of heavy toxic volcanic ash covered the mountain
What did ash falls cause?
Roofs collapsed under the weight
Killed plants as they couldn’t do photosynthesis causing habitat loss.
Respiratory issues for animals and humans.
how far away was the furthest tephra crater
almost 1km away
Who helped to rescue people?
500 firefighters and Japan self defence force.
