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Tom Mazanec
2017-Jun-12, 04:35 PM
Is such a large "hypereruption" possible or impossible, theoretically?

schlaugh
2017-Jun-12, 05:54 PM
Who can say? A VEI 9 event (and I had to google the term) may have already taken place but is buried in geological strata (http://geology.com/stories/13/volcanic-explosivity-index/):


Why Does the Scale Stop at VEI 8?The largest explosive eruptions that have been documented to date have been rated at VEI 8. Could eruptions larger than Toba, Yellowstone, and other VEI 8 events occur? Does Earth have the ability to produce a blast capable of launching the 10,000 cubic kilometers of ejecta needed to rate a VEI 9 eruption?


It is possible that evidence for a VEI 9 eruption exists and is buried in the geologic record. Eruptions that large would be very rare events, but it is impossible to say that eruptions that large have never occurred. If an eruption that large were to occur in the future, it would be a significant threat to life on Earth.

BigDon
2017-Jun-13, 08:41 PM
(Wouldn't 10,000 cubic kilometers of Earth rock make a decent moon? Differentiated and everything? )

Okay, that's at least half of the continental United States being catastrophically relocated. The Chicxulub Impactor didn't do that much damage and it still took 5 million years for large animals to reappear.

This is like the old joke about the guy who cleaned all the wax out of his ears and his head collapsed. Possible but not probable.

dgavin
2018-Sep-03, 04:39 AM
VEI-9. There is a lot of debate on this if that should be added to the scale or not. The largest known stratovolcano or supervolcano eruption is the La Garita Caldera in Colorado. It ejected around 5000^3km. In 2004 there was some talk about it being rated as A vei 9.2 but according the scale it would rate an 8.5 VEI.

So the question is; is there any eruption that would qualify for e a VEI 9? Yes, just one. The Columbia River Basalt Group while a fissure type eruption, has one (of many) flows which produced an estimated 10,000^3km. All told over about 2 million years, the CRBG flows combined produced 50,000^3km of flow ejecta. So it's largest flow just barely qualifies as a VEI 9 event. And the Combined of all flows, qualifies as a VEI 9.5.

Swift
2018-Sep-03, 01:49 PM
dgavin

Nice to see you again

dgavin
2018-Sep-03, 04:06 PM
Thank you, haven't meant to be absent for so long, but well just life been very diffent these days. Shoot me a IM if you'd like details.

Back on topic, the Siberian Trap's while immensely larger than the CRBG, didn't have a single large flow of VEI 9 scale. Overall though as it also was active for 2 million years, the amount of ejected flows places the total output of the traps at a VEI 11.4 (4 mill cubic km of flows). So while a much larger breakout then the CRBG, it did not have the single large event which CRBG did.

Roger E. Moore
2018-Sep-05, 01:08 AM
Maybe we juuuuuuuuuuuuuust missed it.


https://www.sciencedirect.com/science/article/pii/S0040195115006757?via%3Dihub

Was there a super-eruption on the Gondwanan coast 477 Ma ago?

G.Gutiérrez-Alonso, J.C.Gutiérrez-Marco, J.Fernández-Suárez, E.Bernárdez, F.Corfu
Tectonophysics, Volume 681, 20 June 2016, Pages 85-94
https://doi.org/10.1016/j.tecto.2015.12.012

Highlights
• Dated ash-fall beds (K-bentonites) from NW Iberia yield a consistent age of 477 Ma.
• Coeval K-bentonites are interpreted to be linked to a single volcanic event.
• Volume estimations of ejecta range from tens to hundredths of km3.
• Volcanic Explosivity Index ranges from Colossal (6) to Mega-colossal (7).
• Further work may reveal that the super-eruption was larger than herein estimated.

Precise zircon and monazite ID-TIMS U–Pb dating of three Lower Ordovician altered ash-fall tuff beds (K-bentonites) in the Cantabrian Zone of NW Iberia yielded coeval ages together with an equivalent previously studied sample (477.5 ± 1 (Gutierrez-Alonso et al., 2007)), of 477 ± 1.3 Ma, 477.2 ± 1.1 Ma and 477.3 ± 1 Ma, with a pooled concordia age (all analyses in the four samples) of 477.2 ± 0.74 Ma. A conservative estimation of the volume and mass of the studied K-bentonite beds (using exclusively the CZ data) yields a volume for the preserved deposits of ca. 37.5 km3 (Volcanic Explosivity Index — VEI = 6, Colossal). When considering other putative equivalent beds in Iberia and neighboring realms (i.e. Armorica, Sardinia) the volume of ejecta associated to this event would make it reach the Supervolcanic–Apocalyptic status (VEI = 8, > 1000 km3). At variance with most known cases of this kind of gigantic eruption events, geological observations indicate that the studied magmatic event was related to continental margin extension and thinning and not to plate convergence. We speculate that a geochronologically equivalent large caldera event recognized in the geological record of NW Iberia could be ground zero of this super-eruption.

Roger E. Moore
2018-Sep-05, 01:44 PM
Is such a large "hypereruption" [[VEI 9]] possible or impossible, theoretically?

A VEI-9 volcanic eruption is kind of like a Category 6 hurricane, or a MMI magnitude XIII earthquake, or any other variation of the "Spinal Tap" joke about turning the volume up to 11. The existing measurement scales for natural disasters already incorporate extremely powerful events in their uppermost level (anything greater than VEI-8 is still VEI-8). The question is valid but makes more sense as looking at VEI-8 volcanic eruptions and asking what would be the theoretical limit.

If everyone did decide to extend the scale, a VEI-9 (unless I am messing up) would blow 10,000 cubic kilometers of material upwards, which is about the size of a cube 28.8 miles along each side. I'm thinking only the close passage of Bronson Alpha (When Worlds Collide) would induce an explosion that would blow Mount Everest into the air.

Roger E. Moore
2018-Sep-05, 01:57 PM
This might help.

https://www.sciencedirect.com/science/article/pii/S0012825210000814?via%3Dihub

The largest volcanic eruptions on Earth

Scott E. Bryan et al.
2010

Large igneous provinces (LIPs) are sites of the most frequently recurring, largest volume basaltic and silicic eruptions in Earth history. These large-volume (> 1000 km3 dense rock equivalent) and large-magnitude (> M8) eruptions produce areally extensive (104–105 km2) basaltic lava flow fields and silicic ignimbrites that are the main building blocks of LIPs. Available information on the largest eruptive units are primarily from the Columbia River and Deccan provinces for the dimensions of flood basalt eruptions, and the Paraná–Etendeka and Afro-Arabian provinces for the silicic ignimbrite eruptions. In addition, three large-volume (675–2000 km3) silicic lava flows have also been mapped out in the Proterozoic Gawler Range province (Australia), an interpreted LIP remnant. Magma volumes of > 1000 km3 have also been emplaced as high-level basaltic and rhyolitic sills in LIPs. The data sets indicate comparable eruption magnitudes between the basaltic and silicic eruptions, but due to considerable volumes residing as co-ignimbrite ash deposits, the current volume constraints for the silicic ignimbrite eruptions may be considerably underestimated. Magma composition thus appears to be no barrier to the volume of magma emitted during an individual eruption. Despite this general similarity in magnitude, flood basaltic and silicic eruptions are very different in terms of eruption style, duration, intensity, vent configuration, and emplacement style. Flood basaltic eruptions are dominantly effusive and Hawaiian–Strombolian in style, with magma discharge rates of ~ 106–108 kg s−1 and eruption durations estimated at years to tens of years that emplace dominantly compound pahoehoe lava flow fields. Effusive and fissural eruptions have also emplaced some large-volume silicic lavas, but discharge rates are unknown, and may be up to an order of magnitude greater than those of flood basalt lava eruptions for emplacement to be on realistic time scales (< 10 years). Most silicic eruptions, however, are moderately to highly explosive, producing co-current pyroclastic fountains (rarely Plinian) with discharge rates of 109–1011 kg s−1 that emplace welded to rheomorphic ignimbrites. At present, durations for the large-magnitude silicic eruptions are unconstrained; at discharge rates of 109 kg s−1, equivalent to the peak of the 1991 Mt Pinatubo eruption, the largest silicic eruptions would take many months to evacuate > 5000 km3 of magma. The generally simple deposit structure is more suggestive of short-duration (hours to days) and high intensity (~ 1011 kg s−1) eruptions, perhaps with hiatuses in some cases. These extreme discharge rates would be facilitated by multiple point, fissure and/or ring fracture venting of magma. Eruption frequencies are much elevated for large-magnitude eruptions of both magma types during LIP-forming episodes. However, in basalt-dominated provinces (continental and ocean basin flood basalt provinces, oceanic plateaus, volcanic rifted margins), large magnitude (> M8) basaltic eruptions have much shorter recurrence intervals of 103–104 years, whereas similar magnitude silicic eruptions may have recurrence intervals of up to 105 years. The Paraná–Etendeka province was the site of at least nine > M8 silicic eruptions over an ~ 1 Myr period at ~ 132 Ma; a similar eruption frequency, although with a fewer number of silicic eruptions is also observed for the Afro-Arabian Province. The huge volumes of basaltic and silicic magma erupted in quick succession during LIP events raises several unresolved issues in terms of locus of magma generation and storage (if any) in the crust prior to eruption, and paths and rates of ascent from magma reservoirs to the surface.

Available data indicate four end-member magma petrogenetic pathways in LIPs: 1) flood basalt magmas with primitive, mantle-dominated geochemical signatures (often high-Ti basalt magma types) that were either transferred directly from melting regions in the upper mantle to fissure vents at surface, or resided temporarily in reservoirs in the upper mantle or in mafic underplate thereby preventing extensive crustal contamination or crystallisation; 2) flood basalt magmas (often low-Ti types) that have undergone storage at lower ± upper crustal depths resulting in crustal assimilation, crystallisation, and degassing; 3) generation of high-temperature anhydrous, crystal-poor silicic magmas (e.g., Paraná–Etendeka quartz latites) by large-scale AFC processes involving lower crustal granulite melting and/or basaltic underplate remelting; and 4) rejuvenation of upper-crustal batholiths (mainly near-solidus crystal mush) by shallow intrusion and underplating by mafic magma providing thermal and volatile input to produce large volumes of crystal-rich (30–50%) dacitic to rhyolitic magma and for ignimbrite-producing eruptions, well-defined calderas up to 80 km diameter (e.g., Fish Canyon Tuff model), and which characterise of some silicic eruptions in silicic LIPs.

Roger E. Moore
2018-Sep-28, 10:38 PM
An article on anticipating and preparing for very large volcanic eruptions.



https://pubs.geoscienceworld.org/gsa/geosphere/article/14/2/572/529016/Anticipating-future-Volcanic-Explosivity-Index-VEI

Anticipating future Volcanic Explosivity Index (VEI) 7 eruptions and their chilling impacts
Chris Newhall Stephen Self Alan Robock
Geosphere (2018) 14 (2): 572-603.Research Article|February 28, 2018

INTRO: Worst-case or high-end subduction-related earthquakes and tsunamis of 2004 and 2011 are painfully fresh in our memories. High-end subduction-related volcanic eruptions have not occurred in recent memory, so we review historical and geologic evidence about such eruptions that will surely recur within coming centuries. Specifically, we focus on Volcanic Explosivity Index (VEI) 7 eruptions, which occur 1–2 times per thousand years.

A variety of environmental changes followed the VEI 7 eruption of Rinjani (Samalas), Indonesia, in CE 1257 and several more eruptions of VEI 6 or 7 that occurred in the succeeding few centuries. The Rinjani eruption and its impacts are relatively well documented, modeled, and, for the purposes of attribution, uncomplicated by antecedent eruptions. It seems likely that the Rinjani eruption triggered the onset of the Little Ice Age, and subsequent large eruptions sustained it. Although climatic effects of eruptions like Pinatubo (Philippines) and even Tambora (Indonesia) lasted only a few years, it seems that coupling of oceans, sea ice, and atmosphere after larger eruptions can force decade- to century-long cooling, decreased precipitation, and major impacts on crops.

The next VEI 7 will affect a world very different from that of CE 1257. Today, populations within 100 km of candidate volcanoes range from fewer than 1000 people in remote areas to between 20 and 30 million people near several candidates in Indonesia and the Philippines. If a VEI 7 eruption occurs, those populations will be at dire risk, and eruptions in some locations could destabilize financial centers, national economies, and even peace between nations. Distal effects on air travel, the global positioning system, and climate will be felt by a high-technology, globally interdependent world.

We suggest and apply criteria to identify candidates for future VEI 7 eruptions, and discuss likely challenges for short-range forecasting of such events. Preparation for such low-probability but high-consequence events is difficult to imagine, yet some modest early measures can be considered. Volcanologists should refine geologic histories and ensure at least baseline monitoring of candidate volcanoes, and consider how they will judge the likelihood that an impending eruption will be of VEI 7. Forward-thinking governments and industries would be wise to consider how a proximal or distal VEI 7 eruption will affect their jurisdictions, and what responses make the most economic and sociopolitical sense.

Tom Mazanec
2018-Oct-02, 06:09 PM
So turtledove's idea of a "Decade Without Summer" in his Supervolcano Trilogy is plausible!

Tom Mazanec
2018-Oct-14, 03:23 AM
Bobby Akart's new survival series Yellowstone imagines a VEI 9 eruption of Yellowstone.

Tom Mazanec
2018-Oct-15, 02:01 PM
Interestingly, the Esperanto Wikipedia has a listing of VEI 9 in its article:
https://eo.wikipedia.org/wiki/Vulkan-eksploda_indikilo