Forecasting geological disasters

[bjdeming]

This is totally different from the Nankai Trough earthquake hazard and it is in South America, not Japan. Also, the news seems boring to everyone but a few academic specialists, since the volcano in question -- Uturuncu -- is in a remote part of the Andes.

Boring, unless you know something of the backstory. I know only a little tiny bit, but it's enough for me to have already planned a chapter on Uturuncu in a Patreon series on supervolcanoes that I hope to get going before year's end, if I can finish a writing commitment on the blog by then.

It will be the last chapter, on the chances of successfully detecting a supereruption before it happens.

And supereruptions are definitely geological disasters (I don't agree with much of the response suggestions they make here, but Donovan and Oppenheimer do convey the worst-case scenario of what a supereruption might do to us; if you read it, just keep in mind that there are other scenarios proposed by other great minds, too).

Trying to keep things brief but coherent (references available on request):

• Believe it or not, and all drama aside, some volcanologists say that we're living in an age of supereruptions, though one has to take the deep-time perspective to see it. On the geological time scale, for instance, Toba and Taupo's blasts were quite recent.
• South America's Andes region is in the midst of an ignimbrite flareup -- a whole series of supersized and just plain big eruptions, similar to the one tens of millions of years ago, not geologically recent, that shaped so much of the US West. (Again, this is not an imminent disaster threat, given the time scale.)
• Uturuncu is in that general region but is not a supervolcano. It does sit among known supervolcanoes, though, and like them is located over the world's largest known magma body (which is far underground, in lay terms, though fairly shallow in an academic sense; and yes, these volcanoes are watched as closely as possible by responsible and knowledgeable people who will let us know if and when trouble looms).
• That Altiplano-Puna magma body could well just sit there and eventually freeze into a granite pluton. They often do.
• Or not. But it's not something anyone needs to include in their daily burden of existential dread.
• When the land around Uturuncu started to deform -- this also happened around a nearby nonsupervolcanic system called Lazufre -- volcanologists wondered about the chances of detecting precursory supersized activity here. Needless to say, they were on this like white on rice.
• That linked PLUTONS project is over now, but I think papers still get published. At first glance, I don't know if the paper that sparked today's news is part of that particular effort. They've learned a lot, but no supereruption is in the forecast outlook at Uturuncu or anywhere else in the Andes any time soon.
• Today's news is that Uturuncu is unlikely to erupt.

 

[bjdeming]

Back to Japan. Besides the expected Nankai Trough megaquake near Tokyo, which is on the island of Honshu -- eventually -- another segment of this complex subduction zone off the Japanese archipelago, the Kuril Trench, near the northern island of Hokkaido, also is expected to let go fairly soon.

Per NHK (autotranslated), recently a committee expressed concerns -- in the article, NHK also summarizes coverage it did in 2017:

Earthquake investigation committee: High possibility of imminent massive earthquake in Kuril Trench​

The government's Earthquake Investigation Committee has published a new assessment that there is a risk of a massive earthquake of "magnitude 8.8 or greater" occurring in the "Kuril Trench" off the coast of Hokkaido in the future. Such earthquakes have occurred at intervals of about 350 years in the past, and since it has already been about 400 years since the last one, it is highly likely that the next massive earthquake is imminent...

How imminent is this rueage?

No one can predict such a thing, but there are a few moderately strong quakes starting to occur in the general area, though not as many as occurred farther south near Honshu before the Great Tohoku quake of 2011.

Yet.

 

[bjdeming]

Here's a graphic from another unofficial but knowledgeable source;



X translation: "[Multiple medium- to large-scale earthquakes occur around Hokkaido in a short period of time; what is the cause?]Over the past week, there have been a series of medium- to large-scale earthquakes around Hokkaido (Pacific coast). Looking at the epicenter distribution map, the depth of the epicenter of each earthquake varies, but the three earthquakes in southern Hokkaido and offshore are close to each other, so it cannot be said that they are not related."

Edit: From Wikipedia -- the Japan Trench (that's Honshu to the southwest of Hokkaido; Kyushu, not visible on this close-up and where Sakurajima and several other volcanoes spout and fret, is southwest of Honshu, along with a smaller island whose name escapes me right now):

One nerdy and nondisaster-related fact that shows up well on that graphic is that Japan is not an island arc like, say, the Antilles. It's a part of Eurasia that split off when (as I understand it, though in a very simplified way) the Sea of Japan began to open up as a result of some very complex plate tectonics that most recently were behind the recent New Year's quake disasters on the Noto Peninsula.

 

[bjdeming]

Weather News, however, takes this view (autotranslated):

...Looking at each earthquake, some occurred near the plate boundary and some occurred due to destruction inside the plate, and it is believed that there is not much direct relationship between them...This activity will not immediately lead to a huge earthquake, but it is a good idea to take this opportunity to check evacuation routes and stockpiles again.

 

[bjdeming]

If you watched Godzilla Minus One, those cracks about mistrusting the government aren't just on the script. I've seen a little evidence of it IRL while following a few knowledgeable Japanese on X -- for example, a real-life and effective citizen-led effort to deal with an eruption on Kyushu a few years ago was mentioned by someone who thought it might be a good idea for Kagoshima, near Sakurajima (which has been quite well behaved, BTW, the last few weeks).

According to this article (autotranslated) and some tweets, there are rumors and claims predicting a major earthquake on July 5.

We're all familiar with this sort of thing online, of course. The article quotes a seismologist addressing the issue this way (especially in parts 3 and 4, but the headline sums it up) via GT:

Why are various hypotheses such as the July 5 "major earthquake" theory supported? "If we don't convey the true capabilities of seismology, it will lead to distrust" - How information is disseminated to society and how it is received​

​

I don't know much about the situation in Japan, but apparently the public there has problems getting information sometimes.

We are lucky to have an agency (the USGS, and its various entities) that's transparent and has proven reliability in geological emergencies as well as potential rumor/false-information magnets like Yellowstone.

They say in other contexts exactly what the JMA tweeted this past week about that rumor: it is impossible to precisely predict an earthquake on such-and-such a date or in such-and-such a place.

What's tricky to convey, given the misleading apparent solidness of volcanoes and faulted ground right up until the moment when chaos breaks loose, is the uncertainty that's involved in real forecasts and warnings. And the public needs to try to understand what that involves, though this is much less fun than clicking on sensational headlines or reading a doom'n'gloom manga, etc.