Mt. Fuji

History of Mt. Fuji volcano (from brochure)

The volcano we currently know as Mt. Fuji was formed over hundreds of thousands of years in a process that can be divided into three distinct phases of volcanic activity.

Komitake Fuji Period (700,000 - 200,000 years ago)

700,000 to 200,000 years ago, at the time of the Beijing Man (Homo erectus pekinenses) and when the Japanese climate was passing in and out of glacial and interglacial periods, Japan was undergoing and active volcanic period.  The Komitake Volcano, the "base" on which Mt. Fuji later developed, is believed to have been formed during this period by an accumulation of hardened lava and volcanic ash that eventually reached 2,500 meters in hight.  The Ashitaka Volcano was also erupting to the south at the same time.  For the tens of thousand of years between the end of the Komitake Fuji Period and the later Older Fuji Period, Komitake was exposed to the elements and underwent significant erosion.  Today, a part of Komitake's crater wall can be seen at Izumi-go-Take near Mt. Fuji's 5th Station. 

Older Fuji Period (80,000 - 16,000 years ago)

The eruptions that would form the Older Fuji Volcano began on Komitake's souther side.  It is presumed from analysis of volcanic ejecta that the eruptions of about 25,000 years ago (during the Weichsel Glacial Period) were particularly violent.  Mud and pyroclastic flows created a layer of impermeable rock, which in turn helped to bring about an abundance of spring water around the Fuji area.  It is believed that the winds carried volcanic ash from Older Fuji all the way to the Kanto region.  After such repeated eruptions, Older Fuji reached a height of about 2,700 meters.

Younger Fuji Period (14,000 years ago - The Present) 

About 10,000 years ago, eruptions that would later form the Younger Fuji Volcano broke out between the respective craters that formed Older Fuji and Mt. Komitake.  These eruptions eventually covered the peaks of both these older volcanos, forming the Fuji that we see today.  The eruptions grew less violent, and by 8,000 years ago Younger Fuji had attained the beautiful shape it has today.  About 20 eruptions of Mt. Fuji have been documented since the start of recorded history in Japan.  The most recent eruption occurred in 1707, forming a new crater named Hoei-zan and spreading ashes all the way to Tokyo (then named Edo).  Records indicate that the sky was so dark with ash that even in the daytime one could not read without the aid of artificial light.  Recently, however, researchers have been busy analyzing the claims of a document - discovered in Numazu, Shizuoka - that indicates that there may also have been a steam-like eruption of Mt. Fuji in 1770.

Lunch on the Tour

Paige didn't really appreciate lunch.  Madeline, however, was a true sport about it and tried just about everything. 

The weather really didn't want to cooperate with us today and our trip around the lake was a bit wet.  By the time we arrived at the train station for our trip home by Shinkansen (bullet train), we had to make frequent stops due to typhoon like wind and rain conditions.  We made it back to our hotel safe and sound though in the end.  Madeline is becoming quite the navigator of Tokyo train and subway stations!!