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Measuring extreme events

bjdeming

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I've had this at the back of my mind since last December and all the discussions here about the EF scale.

The arguments reminded me of the controversy over the term "supereruption" and "supervolcano," which still crops up sometimes, though it's not as heated (pun intended) as it was twenty years ago.

Nowadays the focus of online criticism, as shown at that link, is more on "supervolcano" as a "sensational media buzzword."

I can't find any of the many scientific anti-"supereruption" essays that came out around the turn of the century, when the public first realized (I think) that something big had once happened at Yellowstone.

From that moment on, Yellowstone stopped being the home of Yogi Bear and Boo Boo and became something epic -- fascinating but scary, too.

In the ivory halls (more like linoleum and plaster), perhaps "supereruption" became acceptable as more research showed volcanologists just how many VEI 8 events show up globally in the rocky record. (Relax -- such extreme events are even rarer than VEI 6's like Krakatoa (Krakatau) 1883 and VEI 7's like Tambora 1815.)

But "supervolcano" is considered sensational. Why?

Because of how we members of the public react to news like this: both Krakatau and Tambora are on elevated alert status right now.

It helps to know that Krakatau erupted yesterday and the world did not end. Fact is, such volcanoes have "normal" eruptions most of the time.

So do supervolcanoes. But everybody is very, very touchy about those.

This became very clear in the 1980s, when the USGS detected unrest at the Long Valley supervolcano near Modesto, California. Check this 1990 NY Times story and this 2016 case study.

The problem is exacerbated by uncertainties about how big an eruption will be before it happens. From what I've read, experts expect an impending supereruption to have supersized precursors -- but they can't be certain of those until one happens.

This is only a docudrama (a good one overall) -- and therefore it had to be a supereruption -- but they did enjoyably capture, at around the 3-minute mark, the extra challenges faced by volcanologists monitoring a volcano that has had supereruptions in the past:



Leave it to the BBC to include stampeding buffalo. :)

OK, for weather, it was that silly "finger of God" business in "Twister."

Movies aside, Yellowstone's next eruption is likely to be "normal," but how would you announce the news of the impending event?

Seismometers, gas and temperature measurements, and other techniques put volcanologists in a somewhat better situation than mets who cannot predict any specific tornado event until it's close (thank you for extending the warning times! ❤ )

From what I understand of the EF-ratings debate, the issue involves judgement calls after the event.

Volcanologists seem to have gotten over the understandable scientific hesitancy to accept the possibility of catastrophic extremes, but they need to make their judgement calls before the event.

It can be done. Mount Merapi, in Indonesia, is a rather violent active stratovolcano, but every ten years or so, it has terrible paroxysms.

Volcanologists are very familiar with Merapi's moods, and they went out on a limb in 2010 because of this knowledge, evacuating hundreds of thousands of people.

And the volcano went back to sleep, like at Long Valley in 1982, right?

No, it went on an almost biblical rampage the next day, but "only" 341 people died, per the USGS.

There are wins, in natural hazards prediction. I guess we can help make more happen by becoming as volcano aware as possible -- and also aware of the difficulties experts face as they try to keep us safe.

(Psst -- don't tell anybody, but the boffins just sit around drinking coffee all day and reading online tabloids. They'll know that trouble is really on the way when those stop telling everyone that Yellowstone is gonna blow.)
 
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