Mt. Fuji - The danger that lurks beneath

Mt. Fuji - The danger that lurks beneath

We brought you news that on June 22, Mt. Fuji finally received World Heritage site status by UNESCO.  The mountain's symbolism for the country and natural beauty cannot be denied, and it is something of a pilgrimage destination for people, not only from Japan, but from around the world.

But Mt. Fuji's new-found recognition may have been just in the nick of time, as danger lurking underneath the surface could radically change what it means to Japan.
 
About 100km southwest of Tokyo, rising to a height of 3,776 meters straight up in an almost perfect cone, unique in every respect from the surrounding countryside, it is hard not to admire Mt. Fuji's beauty, and for some, to wonder about how it got there and what is in store for its future.
 
The reality is that it is an active volcano, which experts say will not only erupt again, but will probably do so quite soon.  There is a consensus among many experts that it may erupt sometime in the next 3 years, with many saying sometime in 2014.
 
And what are the reasons for this prediction?
 
1) There have been thousands of earthquakes under and around Mt. Fuji over the last few years, particularly since the major Tohoku earthquake in 2011, which is a clear sign of activity under the volcano.
 
2) Experts say that the pressure of the magma under the mountain is building, and is currently measured to be about 1.6 megapascals.  How much pressure is this?  Experts say that this pressure figure likely exceeds the pressure under the mountain the last time it erupted in 1707.
 
3) Preceding the 1707 eruption by about 4 years, on December 31, 1703 was a major 7.9-8.2 magnitude earthquake, relatively close to Tokyo, which was followed by a massive 8.4-8.7 earthquake on October 28, 1707 off of Wakayama prefecture several hundred km to the southwest.  Only 49 days later, on December 16, 1707, Mt. Fuji erupted.  It is commonly thought that a major earthquake in Mt. Fuji's general area could setoff the required chain-reaction for a major eruption, and many say that the Tohoku earthquake of 2011 in the north of Japan could have already set this process in motion.
 
4) There have been reports of the water level of some of the lakes surrounding Mt. Fuji changing significantly and that Kawaguchi Lake, known for natural gas coming up from the lake bottom, is experiencing huge increases in the amount of gas being emitted.
 
5) Still another factor pointing toward a major eruption is that it is commonly thought that preceding a major event like a Mt. Fuji eruption are smaller events in the surrounding region.  Mt. Fuji is the massive main volcano in a region with many surrounding lesser volcanos.  Over the last several years, there has been an increase in events in the area, notably volcanic activity off the coast of nearby Izu peninsula (Izu-tobu-kazangun), the nearby island of Izu-Oshima, and most famously, the island of Miyakejima, in 2000-2002, which had to be evacuated, and is still smoking to this day.
 
The graphic below shows the progression of activity that began in the 1980s.
 
Source: spaaqs.ne.jp
 
But would an eruption of Mt. Fuji really be such a major event for Japan?  Please take a look at this graphic that shows 10-50 cm of ash in the major populated area of Shonan, Kamakura, etc.  And with prevailing winds blowing east from the mountain, it is predicted that Tokyo will see 2-10 cm.
 
Source: bousai.go.jp
 
Experts say that with this amount of ash, no machinery can operate, meaning no transportation of people, food, supplies, or otherwise can happen.  And the weight of this amount of ash could literally cause buildings to collapse and would clog up much of the metro area.  And of course, most seriously, people would not be able to breathe without masks or other precautions which could mean a terrible toll of life for people who are not prepared.
 
And as things stand now, are people prepared?  Our informal observations say not all.  In fact, many people in Tokyo are not even aware of the potential seriousness of the problem.
 
So what would an event like this mean for Japan in the long term?  Given that the Tokyo metro area is the heart of the Japanese economy, it could mean a crippling of the world's 3rd largest economy for years.
 
We will bring you more updates and new information as news unfolds here in Japan.
 
Other image sources: Wikipedia, keizai.biz
 
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