At least 30 people presumed dead on erupting Japanese volcano

[Johnny_L.A]

Link

The volcano in central Japan unleashed a huge cloud of ash late Saturday morning that billowed down the mountainside and engulfed hikers in its path.

There is video at the link, showing the ash engulfing the hikers.

[notfrommensa]

From the article:

The Japan Meteorological Agency has raised the Volcanic Alert Level for Ontake from 1 to 3. That means the public is advised to not approach the volcano, the summit of which is at an altitude of 10,060 feet (3,067 meters).

Wow, What does it take for the agency to prohibit people from going to the volcano?

Wiki says the US has 4 levels of VAL (Dormant, Advisory, Watch, and Warning). What the VAL was 24 hours before the eruption?

If Mount Ontake was at Advisory (or lower), the VAL is pretty worthless as a public service.

[Broomstick]

Part of the problem is that we can’t predict eruptions.

For a very few heavily studied volcanoes that erupt fairly frequently yes, we can point to some indicators that usually (but do not always) appear prior to an eruption, but they differ for each volcano and that only applies to volcanoes that have erupted fairly recently, say within the past 50 years, so we have some sort of decent record of prior eruptions.

Even then, a volcano can still surprise us.

Also, volcanoes are inherently dangerous. This really isn’t a major huge eruption - it belched an ash clouds with a few rocks in it. That’s a lot different than, say, blowing the side off a mountain (like Mount St. Helens) or a pyroclastic flow (what ate Pompeii) or something that prevent anyone approaching at all for weeks or months.

By the time you get to the high end of the volcano event scale it’s probably physically impossible to get near the caldera.

And frankly, if liquid rock, steam, poison gas, ash clouds, and red-hot rocks falling like hail don’t say “do not approach” to a person I’m not sure, exactly, what mere words or a number on a scale are going to do.

I don’t think the warning scale is so much for people ON the mountain - they pretty much know what’s going on and those that can are getting themselves off without being asked - but rather for people at a distance who might be curious or not entirely aware of the situation.

[buddha_david]

@notfrommensa

What the VAL was 24 hours before the eruption?

All the reports I’ve read say the eruption happened without warning. Volcanology is not a perfect science.

[Ale]

Yikes… I’ve been there skiing

I didn’t know it was an active volcano.

[Grumman]

From Wikipedia:

Ontake was thought to be inactive until October 1979 when it underwent a series of eruptions, ejecting 200,000 tons of ash in total.

There were minor eruptions in 1991 and 2007 and a low-level eruption alert in 2008.

[notfrommensa]

I realize the predicting volcano eruptions is not a perfect science but neither is predicting Earthquakes. And there is not an Earthquake Alert Level.

[muldoonthief]

I guess it’s a good thing this volcano didn’t erupt in Italy then.