Japan (AC) - living with volcanoes

Background context

- Japan has 110 active volcanoes
- Several submarine volcanoes just offshore from the Japanese mainland.
- 70% Japan's land mass = mountainous, formed by volcanic activity over millions of years.
- Mount Fuji and several other volcanic peaks = important part of Japanese culture + tradition.

Japan's tectonic setting

- Located in one of the most tectonically active zones in the world.
- Where 4 tectonic plates meet & widespread subduction gives rise to intense volcanic activity.
- Nearly 1200 volcanic eruptions over the past 2000 years.
- Average frequency of eruptions at different scales suggests that the more explosive the eruption, the less its frequency.

Which volcano erupted

Mount Ontake

What is Mount Ontake

- Classic stratovolcano 200km west of Tokyo.
- Rises 3000m and the summit is often snow-covered.
- Dormant for many centuries until a sequence of eruptions between 1979 and 1980.
- The area was popular with climbers and trekkers and was a noted tourist destination with various facilities (lodge near the summit.)

When

- 27th September 2014 just before midday: Mount Ontake erupted violently without warning.
- At the time, the volcano wasn't under any alerts or warnings.
- Some increase in earthquake activity had been observed.

Impacts

- 63 killed.
- Large areas surrounding the volcano = affected by ash fall, pyroclastic flows, tephra.
- Most casualties = hikers and climbers on the slopes of the volcano.
- More than 200 survivors made it down.
- Search and Rescue teams were deployed to recover those with serious injuries.
- Japanese Prime Minister Shinzo Abe ordered the military to assist with emergency rescue operations.

Important

Even in Japan with one of the most sophisticated monitoring and warning systems in the world, the country can be taken by surprise by the unpredictability of tectonic hazards.

Why do people live there

- Millions have little choice but to live alongside active or dormant volcanoes and many experience many earth tremors.
- Slopes of volcanoes often attract settlement
- Japan's agricultural sector uses 13% of land area intensively - high fertility of volcanic soils.
- Tourism can lead to tragedy.
- Exploiting geothermal energy.