Mount Ontake

Question 1

Facts

Answer 1

• 27th september 2014
• 200km west of Tokyo
• First fatal volcanic eruption since 1992

Question 2

Causes:

Answer 2

• Japan is on a triple plate subduction boundary between the Philippine and Pacific oceanic plates and the Eurasian continental plate. The denser oceanic plate subducted under the Philippine and Pacific plate which has formed the fold mountains.
• The high pressure due to intense friction at the boundary has melted rock - the magma rose up the continental plate and formed a plug since the magma is very viscous

Question 3

Impacts:

Answer 3

• 57 people died and 6 still missing
• Trapped 250 on the mountain because of the pyroclastic flow
• 40 people injured
• Heavy toxic volcanic ash covered the majority of the mountain - up to 50 cm thick
• Ash cloud travelled down the mountain 3 km
• Visibility was reduced with some people engulfed into total darkness for several minutes
• Most of the victims died due to inhalation of toxic gases and flying material
• 40 people injured by flying rocks and inhaling gas
• Loss of imedicate tourism
• Waves of burning chemicals which destroyed habitats and increased the animal death toll
• People were buried alive
• The eruption caused an eruption of ash causing an ash cloud and low-density, low-temperature pyroclastic flow

Question 4

Responses:

Answer 4

• 1000 rescue workers (police, firefighters and military personnel) went in search on the mountain after the eruption which trapped hundreds of people
• Rescue efforts were hampered due to the conditions where the volcano was still erupting gases, rock and ash. Residents were warned of a risk of falling stones
• Rescue helicopters were deployed
• Emergency descent by hikers
• Rescue teams sent out while the volcano was still erupting - danger

Question 5

Management:

Answer 5

• Increased seismic activity but no sign of an eruption
• It is possible to monitor a volcano and predict when/ if the volcano is going to erupt. Eruptions can be predicted by magma movement under the volcano and also the release of sulphur dioxide - if these are monitored it can be possible to predict an eruption; but this can only happen if the volcano has been monitored in a previous eruption but this has not happened for previous eruptions.
• Also along with no data the movement of magma and tremors can occur without an eruption
• Along with this the type of eruption which occurred does not normally have the typical signals when a volcano erupts