A simulation was released by the Japanese government showing what could happen if Mount Fuji, the most famous active volcano in Japan, would erupt again today.
The Central Disaster Management Council organized the project which ran models predicting eruptions at 92 different vent locations on Mount Fuji. The lava could reach the outer edges of Tokyo, but the primary danger will come from the ash that the volcano will produce as it could fall through the air for several days or even several weeks.
Mt. Fiji simulation
According to a report in The Asahi Shimbun, in the worst-case scenario, more than 17.3 billion cubic feet of volcanic ash would fall over Tokyo and the surrounding areas. That would be equivalent to 10 times the amount of debris that had to be cleared from the city after the Tōhoku earthquake and tsunami in Japan in 2011.
The first signs of ash falling could be felt in as little as three hours and the city would be shut down just within 24 hours because of the ash, according to the report. With just a one-inch layer of ash, the simulation says that roads would be buried and can't be used or two-wheel-drive vehicles because there won't be enough adequate friction.
Also according to the report, even a comparatively light ashfall of around one-fifth of an inch would effectively lower visibility to the point where driving would become impossible. The rail service would be immediately suspended because even a small amount of ash on the tracks would make it unsafe for trains to operate.
Airports would also be restricted because only 0.08 inches of volcanic ash would immediately render runways unsafe for landing planes. The ash would also disrupt mobile phone towers, it could cause power outages and it can render thermal power plants inoperable just after two inches of ash.
The worst effects of the volcanic eruption would be on the people because they would face severe respiratory damage, especially those who already have conditions like asthma. A lot of wooden homes would also face structural damage because of the heavyweight of the accumulated volcanic ash.
The Central Disaster Management Council estimates that it would take three days and a crew of 1,000 bulldozers to clear pathways wide enough for just emergency vehicles to begin driving again. Mount Fuji has erupted around 180 eruptions over the last 5,600 years, but the majority have been small and had little effect on the residents.
The last eruption of Mount Fuji happened in 1707, also known as the 'Hōei' eruption after the Edo calendar period during which the eruption took place. The eruption produced more than 28.2 billion cubic feet of volcanic ash, which immediately fell through the air for two weeks and traveled as far as 62 miles.
The volcanic eruption led to a number of disasters during the following year, including flooding in multiple areas where volcanic ash formed natural dams that blocked the Sakawa River. According to the Council, the simulations are intended to help the local government be prepared for the next disaster to minimize as much unnecessary damage as possible.
Toshitsugu Fujii from the University of Tokyo who worked on the project said that a mistake in the early response could leave millions of people stranded, and it may also not be possible to distribute supplies. It is important to prepare a system to handle the situation in advance.