Monday, 24 June 2013

Triple feature part II: Spotlight on Mt. Fuji

It's time for another volcano profile! This time our focus is the famous Mount Fuji, which even made the news a few days ago (see end of this post). It's really well known (type "Mount Fuji" into Google and it comes up with over 8 Mio. hits in 0.27 seconds...), mostly for its iconic shape - the shape that most people have in mind when they hear the word "volcano". This shape is characteristic for a type of volcano called "stratovolcano". These volcanoes are almost perfectly cone shaped, with relatively steep slopes.
Stratovolcanoes are made up of alternating layers of different types of volcanic materials, for example ash, lapilli (loose pieces of volcanic rock that are bigger than ash), bombs (even bigger pieces of volcanic rock), lava flows, pyroclastic flows (really hot, really fast, really deadly flows of loose volcanic material; see Harry Dalton in the very hilarious and awesome movie Dante's Peak for some insights on the topic... Here's the crucial scene:)

In most cases, stratovolcanoes are made out of very "sticky" rock types like rhyolite or andesite. With rocks it's essentially the same as with honey: There's the real runny stuff, that drips of your slice of toast no matter what, and then there's the type that's more viscous, so that even eating-habit-challenged people like me can finish their breakfast without letting hands and table and chair and pants and shirt enjoy their part of the honey. So the runny rock type (basalt) would form shield volcanoes, because all of the lava just runs down the mountain easily, whereas the sticky rock types actually produce volcanic output that can stick together and form a steeper mountain. Makes sense?

So Fuji-san sits on the island of Honshu, the biggest of all the parts of Japan. It's over 3,700 metres high, and I'm definitely planning on climbing at least part of it when I'm on my way back from Kagoshima to Tokyo in a bit over a month from now! I won't have to be too worried about activity there: The last "big" eruption was in 1707, with a VEI of 5 (see previous post for some info about VEI). Fuji's history in general is quite uncertain, there may have been some smaller eruptions in later in the 1700s and 1800s, but definitely nothing has happened in recent history. They're monitoring it tightly since it's so close to sooooo many people, but at this point there's not too much going on.
However, it did get quite interesting just a few days ago: On Saturday, the United Nations Educational, Scientific and Cultural Organization (UNESCO) announced that Mount Fuji is now officially a World Heritage site (read the full article). Only around 30 volcano-related sites have made it this far! Granted, it was probably given the status not based on it's volcano-y awesomeness but because it's a "sacred place and source of artistic inspiration", but hey, we can give it some credit anyways, don't you think?!


  1. ...and you forgot to mention there are good waves right down by beautiful Fuji-san :)