Mount Fuji has not erupted in more than 300 years. So why are researchers now wary of a potential impending eruption?
The last time Mount Fuji erupted, it was because an earthquake increased the pressure in the mountain’s magma chamber. Last year’s Great East Japan Earthquake, which was a 9.0 magnitude quake, duplicated those conditions — with a 6.4-magnitude aftershock thrown into the mix. Experts now believe that Mount Fuji is likely to erupt within the next three years.
The pressure that is now brewing in Mount Fuji has reached 1.6 megapascals. To put that number in perspective, a pressure of just 0.1 megapascals has been enough to trigger an eruption. No wonder Eisuke Fujita, a senior researcher at the National Research Institute for Earth Science and Disaster Prevention, has stressed that this is no small number. Other signs of an eruption are the steam and gas currently streaming from the crater, as well as a 21-mile-long fault line recently discovered directly below the volcano. If an earthquake were to occur directly on that fault line, Mount Fuji would collapse entirely in a mass of mud and lava.
The Japanese government, however, has done little to prepare for an eruption. Toshitsugu Fujii, the director of the Crisis & Environment Management Policy Institute, said that the smoke and ash from such an event would keep planes from taking off or landing for more than a month. So far, the only precautions include a test run of an evacuation plan for the region — scheduled for 2014.
About 40 million people visited Mount Fuji last year, and the volcano is a huge source of tourist dollars for Japan. The complication, then, is that too much of a panic will drive tourism away. But at the same time, researchers are nervous that the country isn’t doing enough.
“The government should prepare for a logistical nightmare,” Eisuke Fujita said. “They'll have to know how many millions of people, including tourists, they'll need to evacuate from around Fuji … but so far the country's failed to get its act together."
An eruption would cost Japan at least $32 billion, according to official estimates.