Mount Fuji and its Volcanic Potential

Mount Fuji is an extremely important symbol within Japanese culture. It is recreated in art frequently and it is a common practice for Japanese people to hike to its summit in the summer. Located just outside the city of Tokyo, Fuji’s snowy peak can be seen from the centre of the city. Its beauty has captured the attention of people around the world and is potentially the most recognizable mountain in the world. However, many do not realize that Mount Fuji is an active volcano. The last time it erupted was in 1707 as a result of an earthquake and it had devastating results. If the volcano were to erupt today, the affects may be even more disastrous.

The 1707 Eruption

This incident is the largest recorded eruption of Mount Fuji in history and its scale is somewhat difficult to comprehend. A massive amount of debris was ejected from the top of the mountain and showered the city of then Edo and its surroundings. It is estimated that two billion tonnes of tephra were expelled from Fuji, covering the Japanese landscape (Magill et al. 2015). Additionally, remnants of tephra were found in the North Pacific Ocean as far as 270km from the source of the eruption (Magill et al. 2015) This map shows the distribution of debris across the Greater Tokyo Area . Areas closest to the eruption received the largest amount of falling tephra. The Mikuriya area, just to the east of Mount Fuji, was covered by 3 metres of debris and some buildings were completely destroyed by the falling fiery ash and rock (Magill et al. 2015). At the time, the affected area was populated by about 3 million people (Magill et al. 2015).

Potential for Eruption

In the year 2000, scientists began to notice small earthquakes happening deep underneath Mount Fuji; at one point in 2001, about 100 small quakes were recorded in a single month (Cyranoski 2004). This led to a panic from the Japanese government who in turn launched a research project to attempt to understand what was happening inside what was thought to be a peaceful mountain. However, researchers have yet to find any answers due to the somewhat anomalous incident of 1707. It was previously thought that volcanos filled with basalt do not violently erupt due to fact that basalt does not tend to trap gases, an effect which often causes the most violent explosions (Magill et al. 2015). Additionally, according to old records taken at the the time of the eruption, the harshness of the blast seemed to increase towards the end, rather than the usual slowing down (Magill et al. 2015). This all adds up to a high level of uncertainty when it comes to predicting the next eruption, if it ever comes.

Impact and Preparedness

With the capitol of Tokyo and its massive surrounding metropolitan area, the impact of a volcanic eruption could be catastrophic. The area effected by the 1707 eruption is now populated by more than 30 million people (Magill et al. 2015). Falling ash can have numerous negative effects on health as well as grounding flights, damaging cars and corrupting hard drives (Cyranoski 2004). Additionally, the affects of lava are extremely devastating to buildings and other structures. Part of the Japanese research effort was to develop the Mount Fuji Hazard Map, which attempts to predict the spread of lava and tephra and as a result describes different levels of evacuation areas. Along with the map is an entire website filled with specific instructions for evacuations in different areas and conditions.

The Japanese government has attempted to prepare for the potential eruption of the beloved Mount Fuji, but its volcanic activity has proven perplexing for earth scientists and as a result, near impossible to predict. Judging by the effects of the 1707 eruption, a current eruption would have a highly destructive impact on the Greater Tokyo Area.

References

Cyranoski, D. (2004). A sleeping giant stirs. Nature, 428(6978), 12-3. Retrieved from http://

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docview/204534910?accountid=14656

Magill, C., Mannen, K., Connor, L. et al. (2015). Simulating a multi-phase tephra fall event:

inversion modelling for the 1707 Hoei eruption of Mount Fuji, Japan. Bulletin of

Volcanology 77: 81. https://doi-org.ezproxy.library.ubc.ca/10.1007/s00445-015-0967-2