The first, Senkomitake, provided the mountain's core, followed by a basalt layer (Komitake Fuji) several hundred thousand years ago. 

Old Fuji formed over the top of that around 100,00 years ago with New Fuji believed to date back around 10,000 years. 

The volcano sits at the junction of three tectonic plates (the Amurian/Eurasian, the Okhotsk/North American and the Filipino) which form, respectively, western Japan, eastern Japan, and the Izu Peninsula. 

Its most recent eruption (16 December 1707 - 1 January 1708) deposited volcanic ash over the Kanto plain, Tokyo, and as far as the north-west Pacific coast 280 kilometres away. 

The eruption formed a new crater halfway down the mountain's east flank. 

While there has been no activity for three hundred years recent events, including the 2011 Tōhoku earthquake and tsunami, have prompted some concern.

As the focal point of the Fuji-Hakone-Izu National Park the mountain is the most popular tourist site in Japan. 

More than a quarter of a million people make the ascent every year, most planning to catch the sunrise (goraikō, or arrival of light) by making the ascent during the night or staying in huts scattered along the four major access routes to the summit. 

Peak climbing season is from July to August. Visitors are discouraged from attempting the ascent at other times due to extreme weather conditions and the risk of avalanche. 


© Ian Hughes 2017