Hidden Impacts of Ferocious Volcanic Eruption Finally Revealed (sciencealert.com) 20
Long-time Slashdot reader schwit1 shared an interesting article from ScienceAlert:
Undersea volcanic eruptions account for more than three-quarters of all volcanism on Earth, but rarely do we see the impacts. The Hunga Tonga-Hunga Ha'apai eruption of 2022 was a dramatic exception. Its furious explosion from shallow waters broke the ocean surface and punched through the stratosphere, generating supercharged lighting and an atmospheric shock wave that circled the globe several times.
But there was far more to the fallout than satellite images could possibly capture or observers could report. We know the human toll this explosion took, but now a new study investigating the underwater impacts of the Hunga-Tonga eruption has detailed just how ferociously the explosion tore open the seafloor, ripped up undersea cables, and smothered marine life... The team also compiled a trove of data from ship-based sonar, sediment cores, geochemical analyses, water column samples, and video footage to chart the devastatingly powerful upheaval...
Their analyses show at least 6 cubic kilometers (km3) of seafloor was lost from within the caldera — 20 times the eruptive volume of the 1980 Mount St. Helens eruption — and an additional 3.5 km3 of material was blasted out of the Hunga volcano's submerged flanks... That leaves roughly four-fifths of the ejected material in the ocean; material that was funneled into fast-moving density flows that scoured out tracks 30 meters deep in the seafloor and accumulated 22 meters (72 feet) thick in some places.
But there was far more to the fallout than satellite images could possibly capture or observers could report. We know the human toll this explosion took, but now a new study investigating the underwater impacts of the Hunga-Tonga eruption has detailed just how ferociously the explosion tore open the seafloor, ripped up undersea cables, and smothered marine life... The team also compiled a trove of data from ship-based sonar, sediment cores, geochemical analyses, water column samples, and video footage to chart the devastatingly powerful upheaval...
Their analyses show at least 6 cubic kilometers (km3) of seafloor was lost from within the caldera — 20 times the eruptive volume of the 1980 Mount St. Helens eruption — and an additional 3.5 km3 of material was blasted out of the Hunga volcano's submerged flanks... That leaves roughly four-fifths of the ejected material in the ocean; material that was funneled into fast-moving density flows that scoured out tracks 30 meters deep in the seafloor and accumulated 22 meters (72 feet) thick in some places.
They have it wrong. (Score:1, Insightful)
Re:They have it wrong. (Score:4, Funny)
Math time! (Score:3)
3 out of 4 eruptions are in the oceans rather than above them, and the majority don't even come to our attention. The planet's surface is about 1/3 land and 2/3 ocean... but by mass the atmosphere is 1/269 of the ocean. While eruptions are not happening like clockwork, on a global scale they're regular enough that there's nothing happening in the oceans that is a significant problem as a result.
More than that, the really big ones that might go off near people and cause problems? We can't do much about them and the probabilities of the individual potential disasters are small enough that even what we could do... we're not going to.
Watch for tsunamis and have an alternate plan on hand if your nation is under threat and depends on local sea stocks. That's about it.
Re: (Score:1)
Truth buried by bad mods as usual.
Re:Math time! (Score:4, Insightful)
Truth buried by bad mods as usual.
A post can be both true and off-topic.
Your anti-government rant is not relevant to a discussion about undersea volcanoes.
Re: (Score:1)
In response to this statement from OP I am 100% on topic.
"We can't do much about them and the probabilities of the individual potential disasters are small enough that even what we could do... we're not going to"
Either that is also off topic or the mod down to my response was inappropriate. We both know what happened, don't pretend otherwise.
Btw, you're now more off topic than I was. Should you get a mod down? I'm sure you have a reason why not.
Re: (Score:2)
You're waaaaaay off topic. Nothing you said has anything to do with volcanos. Not even in the same universe as volcanos.
The hypocritical cognitive dissonance and intellectual dishonesty are strong in your trollness, AC.
Re:Math time! (Score:4, Interesting)
What they forget to mention is that the vast majority of these underwater eruptions occur along mid-ocean ridges where low silica basalt is erupted without drama several kilometers underwater. This is very different from the situation in Tonga which lies on a subduction zone.
Counting phreatic eruptions and effusive eruptions together really is apples and oranges. But I guess that's as close as earth scientists get to clickbait.
This has gone far enough. (Score:2)
I admit it, it was me. I was on vacation in NZ last year, was feeling a bit gassy but went diving anyway and well... some people took notice as the compressed gas kinda took on a life of it's own.
6 km^3 of seafloor - something is off here (Score:2)
Re: (Score:2)
" 6 cubic kilometers (km3) of seafloor" - seafloor is 2D.
You don't think craters are deep?
Re: (Score:2)
Yep, a minor shortage of neurons somewhere in the system.
They're saying that the volume of the caldera collapse was about 6 cubic kilometers, and this should be comparable to the volume of magma erupted. This puts the eruption in the same ballpark as Mt. Pinatubo's 1991 eruption. The volcano also lost several cubic km from a flank collapse which probably caused a tidal wave.
The important difference is that most of this material remained in the sea, forming underwater clastic deposits rather than being lau
Volcanic heat flux [Re:Just another AI creation.] (Score:4, Insightful)
These volcanos, whether they are erupting or not add more to the temperature of water than man-made global warming.
First: not even close. Total heat flux from the Earth's interior is 87 mW/m2, and volcanic heat flux contributes only about 1% of that (yes, they are hot, but the area is so small compared to the surface area of the Earth that the contribution of volcanoes to the total area is small.) Volcanoes, even undersea ones, don't add enough heat to affect the climate enough to notice.
Second, however, is that we are seeing a steady rise in global temperature. Unless you are proposing a steady rise in global volcanism, that's not the cause of the observed warming..
Re: (Score:2)
However, their flux of greenhouse gases (CO2, H2O) is big enough to notice. However, the GP would probably have a minor epileptic fit on being told that the amount of GHGs emitted by volcanoes is (now) about 1/10th of the anthropogenic ("man created", a.k.a "fossil fuels").
Most of natural GHG emissions are from the continuing, mild bubbling from hot springs, fumaroles, and frequent, small eruptions from minor volca