On the planet Mars, there is a gigantic shield volcano. Recall that shield volcanoes are formed over very long periods as lava spills out relatively freely and continuously, rather than being formed as the result of explosive eruptions. This huge Martian mountain is known as the Olympus Mons. It is about 25 kilometers in height, making Mount Fuji seem very small indeed. However, Mount Fuji is a stratovolcano, formed by very violent eruptions. This volcanic activity has dramatically changed the landscape over time.

Mount Fuji has been an artistic inspiration partly because of its perfect cone shape. However, it doesn’t look this way from all angles, and many people prefer the slightly asymmetrical appearance from Shizuoka Prefecture, for example.

The view of Mount Fuji from the Shinkansen Bullet Train as it speeds through Shizuoka must be considered equally iconic — and, many claim, more beautiful. Notice that the volcano is not quite symmetrical seen from this angle.

Perhaps the asymmetrical view of the volcano is more evocative because it hints at its historical origins. Actually, Mount Fuji has a very long history of volcanic activity going back millions of years. Originally, there was no mountain at all! Then, around 700,000 years ago, a relatively small volcano became active in the area occupied by Mount Fuji now. This is known as Mount Komitake (小御岳火山 — literally, small mountain volcano). The peak of this buried mountain can be seen from the actual summit if you look north towards the Fifth Station. Another small volcano, Mount Ashitaka, became active around the same time.

Mount Komitake eventually calmed down, then started erupting again after about 100,000 years. The mountain grew bigger as lava covered the older volcano with repeated eruptions. Then there was another quiet period lasting about 4,000 years and about 5,000 years ago, activity started up again. This last period is known as New Fuji and continues to the present day. Violent eruptions, of course, have the effect of either plastering smooth layers of lava over the surface or blasting new holes.

Over time, lava has been plastered over older volcanoes to create the smooth, conical appearance.

Featured picture: Utagawa_Kunisada_I_(c._1832)_Dawn_at_Futami-ga-ura