Records showed that Mount Fuji’s last violent eruption was in 1707, and volcanologists put its eruption cycle at 300 to 500 years. There’s been roughly a 300-year quiet period since the last eruption, which may be long enough for the volcano to have built up enough energy for the next eruption, but experts don’t know if the next eruption is close or a hundred years away.
Should Fuji erupt anytime soon, government officials estimate the financial cost to be $21 billion dollars in damage. A considerable worst case scenario given the metropolitan area of Tokyo and Yokohama have a population exceeding 16 million.
Fuji has erupted at least 16 times since 781 AD. Most of these eruptions were moderate to moderate-large in size. Fuji’s largest recorded eruptions occurred in 1050 and 930 BC.
It has been long believed that Fuji had two volcanoes hidden within its cone. However, in April 2004 Japanese scientists discovered a third volcano after extensive deep drilling into the mountain. They have named it Sen-Komitake; it is the oldest volcano of the three.