Mt. Fuji May Be Close To Erupting

SpuriousLogic points out an article at Wired discussing research into pressure levels inside Mt. Fuji's magma chamber, which scientists claim is higher than it was in 1707, the last time it erupted. "The new readings, taken by the National Research Institute for Earth Science and Disaster Prevention, reveal that the pressure is at 1.6 megapascals, nearly 16 times the 0.1 megapascals it takes to trigger an eruption." A series of earthquakes shook the area around Mt. Fuji a little over a decade ago, and a fault line was discovered underneath it. "Since the March 2011 tsunami and the 6.4 magnitude earthquake that followed four days later, Japan has been on tenterhooks, and in May 2012 a professor from Ryukyu University warned that a massive eruption within three years would be likely because of several major factors: steam and gases are being emitted from the crater, water eruptions are occurring nearby, massive holes emitting hot natural gases are appearing in the vicinity." While the rising pressure within the magma chamber is of concern, it is but one factor among many that lead to eruptions.

Comments

Another thing to worry about...

[redbeardcanada]

I am going to Japan in October, so in addition to earthquakes, tsunamis, radiation, ninjas, and godzilla, I now also have to worry about lava??? Damn...

Re:Another thing to worry about...

[Rei]

I find it funny to hear all of the worry about things like Fuji. I mean, I know, I get it, it's roughly 100 km from Tokyo, which is a huge super mega-city. But living here in Iceland, hearing other places talking about "active" areas just seems kind of funny. I mean, the ground in parts of the capital region here in Reykjavík is just several hundred years old. On the hill right next to where I work, they drilled a 90 meter pipe into the ground, put a choke on the top, drip in water, and it erupts regularly as a geyser. A quarter of the city's hot water comes right from downtown. I mean, half an hour's drive (plus a bit of a walk) from my house you can walk *inside* a magma chamber. Not a lava tube, the actual magma chamber. It's empty now but there's other active magma chambers in the region.

And we're not considered one of the more active regions.

Fuji erupts every few hundred years, the biggest being VEI 5? Yawn. Katla's been threatening to go off any day now for the past couple years, and she's a VEI 6. And she's got an ice cap on top; last time she had a big eruption, she sent down a flood with as high a flow rate as the average outflow of the Amazon, Mississippi, Nile, and Yangtzee combined. That is, as much water flowing by as would fill up a cube over 200 feet on each side (roughly equivalent to a city block of 20-story buildings), every second.

Japan is volcanically active? As much as a third of the lava on Earth in the past 500 years is estimated to have come from Iceland.

Fuji's last big eruption was in the early 1700s? In the late 1700s we had Laki go off, most devastating eruption in recorded human history. A fissure opened up 23 kilometers long, up to 200 meters wide in places, with lava fountains as much as 1.5 kilometer in the air, erupting for 8 months straight. Sulfur dioxide was equivalent to a Mt. Pinatubo every three days. But that wasn't the worst, the worst was the anomalously high amounts of hydrofluoric acid. The eruption killed 80% of Iceland's sheep and even directly caused 23,000 human poisoning fatalities in the UK from the deadly blood-red cloud, as well as bizarre weather including tremendous thunderstorms with hailstones large enough to kill cattle.

So yeah, yeah, I know, Fuji is more of a threat because Japan has such huge coastal populations and economic activity and stuff, I fully understand that, but still... I guess your perception of risk is relative to your environment.

Evacuation test run next year ???

[ACK!!]

From the article: "Regions that would be affected, including Kanagawa, Yamanashi and Shizuoka, plan to hold a test run of an evacuation by 2014, with a meeting of local governments covering progress of the plans and of shelter preparations slated for April 2013." It seems if the pressure is higher than the last time the damn mountain went boom that they would speed up preparations a tad. Wow, laid back disaster relief.

Re:Evacuation test run next year ???

[chromas]

They don't want to risk premature evacuation.

Re:Evacuation test run next year ???

[magarity]

Its not like everyone can simply form an orderly line and proceed calmly to the nearest exit

Apparently you've never been to Japan.

See some of the pictures from the last earthquake and tsunami; people evacuating the subway stations are stopped and standing to one side in a neat line on the halted escalator to let emergency workers go down past.

Re:In Olde English units

[meekg]

Pressure vessels get increasingly difficult to build as their size grows.

When a 150 PSI compressor tank goes (and they do, even though they are made out of steel, a lot thicker than a soda pop can) they take away the room with them.

This pressure vessel is probably miles on a side, and the walls don't have good tensile strength - it's just gravity that's holding it down.

In short converting it to Olde English units doesn't help.

Re:"Nearly"?

[Anonymous Coward]

My P5 system says 1.6 / 0.1 = 16.000739068902037589.

Re:"Nearly"?

[Calydor]

I'm curious, do you say, "I'll be there in 58 minutes and 48 seconds," or do you say, "I'll be there in an hour?"

I'm pretty sure both the .1 and the 1.6 megapascals is a rough estimate and not a 100% exact, set-in-stone figure.

Re:Drill a hole, relieve the pressure?

[RabidReindeer]

They want to, but Bruce Willis already died in space saving the world from that asteroid.

So who inherits his iTunes collection?

Re:Better rescue the coke machine

[TheRedSeven]

True. Most metal cans (the kind used for packaging, anyway) are coated with a layer of plastic to prevent interaction with the Al/Sn in the metal of the substrate itself. Particularly with acidic contents (tomatoes are the ones that come most readily to mind.) Can *ends* are manufactured separately and joined to the can bodies themselves after filling. Some can ends are coated with plastic over the majority of the surface, but others have perforations and other 'gaps' that allow for proper sealing/seaming between the can and the can end, and for tabs to break through, etc. Any place the plastic coating is missing and an acidic ingredient can come into contact with the metal, corrosion can occur (though slowly).

Source: I'm a market researcher specializing in food/beverage packaging in the US.

Re:"Nearly"?

[flyingfsck]

I wonder how many people here are old enough to get your joke?

Re:how do they know

[ppanon]

They probably figured it out based on the pattern and quantity of ejecta. i.e. to launch boulder of this size this distance and to cover this area with this much ash then, assuming the lava reservoir was roughly the same size as it, the pressure needed to be X.

Re:"Nearly"?

[gman003]

Probably more than you think.

My high school had an Engineering Ethics class, mandatory for all students in a tech-related major. One of the case studies was the Pentium FDIV bug, and how Intel handled it. Other case studies included Tacoma Narrows, Chernobyl, and a bunch of other forgettable ones.

I graduated HS in '09. So "my generation" may be learning about it in a history class rather than through usage, but we *are* learning about it.

In other words, "no, YOU get off the lawn, old man!"