Mount Ontake Flashcards
Location?
Mount Ontake, Japan. 200km west of Tokyo
Height?
3067m tall, 2nd highest volcano in Japan
What is meant by “a phreatic eruption”?
The eruption was phreatic, water seeped into the magma chamber and became superheated steam.
This put pressure on the volcano and caused it to erupt.
When was the eruption?
September 27 2014
What was the total death toll?
57
Why was the death toll so high?
The volcano was a popular hiking trail and due to the nature of the eruption, there were minimal warning signals and the mountain was filled with tourists.
Of the 57 who died, 31 were found near the summit resting, unaware of the imminent danger.
What were some of the main Primary impacts?
Although there was a substantial ejection of hot ash, steam and rocks, due to the nature of the eruption, lava and ash clouds were reduced.
Tephra was ejected into the atmosphere at speeds of over 300 km/h injuring 40.
Hikers and tourists had to flee as the eruption was unexpected.
What were some of the main secondary impacts?
A thin layer of ash increased fertility in the soil without killing it due to limited ash ejected.
On 29th September, rescuers had to abandon their search as the levels of poisonous hydrogen sulphide being emitted by the volcano were becoming too dangerous.
What were some of the main immediate responses?
Around 1000 Japanese rescue workers (a mix of police, firefighters and military personnel) set out to search the peak popular with hikers after its sudden eruption that trapped hundreds on the mountainside.
What were some of the main long term responses?
Not many long term responses as protocol couldn’t be tested due to the unusual nature of the eruption.
What was its VEI rating?
3
