What if Mount Fuji erupted?

[bjdeming]

Tokyo has released a video of what an eruption might be like (Source):



Ashfall is the main threat, with maybe also lava flows for some areas close to the edifice.

Nothing appears to be pending at Fuji-san right now, and no alerts are up (overtourism is the main issue nowadays), but magma has been starting to move intermittently down there since the 2011 megaquake. I set up a post for it a while back, just in case; it has a few useful links.

Of note, though the references aren't in front of me right now, my understanding is that Fuji tends to erupt -- at least recently -- in tandem with Nankai Through megaquakes. This probably was a factor in the video's release, too, since they just renewed the warning that a big quake could happen at any time.

This does not mean that Fuji would go off, too, if a megaquake did occur. An eruption can happen whenever -- or not -- and this is just a possibility they're raising public awareness for. It's a cool video.

 

[bjdeming]

Well, why not throw in another simulated eruption in a city threatened by volcanism (Auckland is built on an active volcanic field), based on news that the Kiwis are planning ahead.



Earth is messing with some tough people here, judging by how they approach sports.

(That can get you in serious trouble in New Zealand, BTW.).

 

[bjdeming]

After all, IAVCEI (the International Association of Volcanology and Chemistry of the Earth) has a whole Cities on Volcanoes program.

 

[bjdeming]

Meanwhile, at Fuji, an expert clarifies the hypothetical situation (Japanese, and yes, Yahoo! is thriving in Japan).

Browser translated excerpt:

...While experts say the video is "significant," they also say it "is insufficient for the people of Shizuoka Prefecture." Masato Koyama, Professor Emeritus, Volcanology, Shizuoka University: There are two types of large-scale eruptions. One is an eruption of Mount Fuji that spews out large amounts of lava. In such cases, even though it's called a large-scale eruption, it's localized. The large-scale referred to by the Cabinet Office and Tokyo Metropolitan Government refers to an explosive eruption, namely the Hoei eruption that occurred during the Edo period. Since they're referring to a similar eruption, which would cause volcanic ash to fall over a wide area, Masato Koyama, Professor Emeritus, Volcanology, Shizuoka University: "An eruption that spews lava, produces pyroclastic flows, or creates snowmelt-type fire mudflows would directly impact cities and towns at the foot of the mountain in Shizuoka Prefecture, requiring evacuation. This has not been emphasized by the Tokyo Metropolitan Government, Cabinet Office, or Tokyo Metropolitan Government. Carefully review the hazard map and take appropriate measures for the phenomena described there...