Information on Volcano

The Volcanic Alert Levels of Izu Oshima volcano is  Level 1 (Potential for increased activity) .

The purpose and points to note of this map

IZU OSHIMA Volcanic Disaster Prevention Map

IZU OSHIMA Volcanic Disaster Prevention Map (PDF)

The Izu-OshimaVolcano is an active volcano that erupts frequently. Although this volcano is currently calm, experts believe that magma accumulation is increasing the likelihood of a future eruption. In addition to providing information, you can use to protect yourself, this map lists actions that should be taken immediately when the risk of eruption is elevated. Understanding specific hazards from past volcanic eruptions will help you take the appropriate actions in the event evacuation is required. However, unlike the weather, it can be difficult to predict eruptions because so much remains unknown about volcanos.

There is a possibility that the volcano can erupt without a moments notice. The Izu-OshimaVolcano may be particularly susceptible to fissure eruptions and lateral blasts near residential areas, the coast, and places other than the crater at the summit. There is also a risk that the volcano could erupt shortly after the occurrence of sudden crustal movement or frequent earthquakes. It is therefore important to note that this map alone does not provide sufficient information on the dangers of a volcanic eruption or the best evacuation strategies.

Please remember, however, that volcanos typically have far longer periods of calm than activity and can be safely enjoyed while dormant.

For tourists climbing Mt. Mihara

The condition of volcanic activity in Izu Oshima

The Volcanic Alert Level in Izu Oshima is Level1 (Be mindful that the volcano is potentially active) now. There is some weak emitting activity in the crater and some other areas atop Mt. Mihara. According to ground deformation observation, Izu Oshima island has been expanding for quite some time. There are periods of active volcanic earthquakes that occur once a year to once every few years. However, these volcanic earthquakes are not common at other times. According to the fieldwork carried out every month, the temperature of the crater has been stable since 1999. Volcanic gas like carbon dioxide hasn't been observed. Based on these observations, the volcanic activity is calm, and no signs of eruption have been detected.

Let’s confirm volcano information

Below is the official Japan Meteorological Agency announcement homepage. It contains news of Izu Oshima's volcanic activity, Volcanic Alert Levels, etc. Please check before climbing Mt. Mihara.

Preparing to climb Mt. Mihara

Mt. Mihara's hiking paths have some areas with poor footholds. Try to wear mountain boots or hiking shoes. To equip yourself in case of a sudden eruption, protective equipment like helmets can be effective in protecting yourself from physical harm. You can rent helmets for free at Mt. Mihara's summit entrance buildings.

Lookout Refuge Rest Area

Free helmet rental

How to protect yourself from a sudden eruption

Volcanic projectiles

  • It is possible for fist-sized volcanic projectiles to fly more than 1km from the site of the eruption.
  • Evacuate to a shelter or hide behind rocks.
  • Protect your head with a helmet or knapsack.

Volcanic ash

  • Unlike ashes formed by combustion, volcanic ashes are tiny particles of lava and are as hard as glass.
  • Cover your face with a mask or a wet towel to prevent inhalation of volcanic ash.
  • If it gets in your eyes, do not rub them.

Volcanic gas

  • Sulphur dioxide has an irritating, unpleasant smell and hydrogen sulfide is a dangerous volcanic gas with the smell of rotten eggs.
  • If you don't have a gas mask, you should cover your mouth and nose with a wet towel and leave the area.
  • Don't enter depressions in the ground because volcanic gas settles there.

In case of a sudden volcanic eruption

Along Mt.Mihara's hiking path, we set up shelters to protect yourself temporarily from volcanic projectiles and volcanic ash. The observation deck on top is also available as a temporary shelter for evacuation. If a sudden eruption occurs at the crater, evacuate to a shelter at safe place away from the site of the eruption. In case of emergency, act accordingly to the circumstances to protect yourself.



Crater Observation