Talk:Volcanic explosivity index/Archive 1

Archive 1

Fix

Than you for fixing the page. 164.64.161.97 17:51, 15 February 2007 (UTC)Dave Someone really messed with this page it is nolonger suitable for the academic use I need. 164.64.161.97 19:01, 8 February 2007 (UTC)Dave Freeborn New Mexico Office of Emergency Management

examples

Looking at both this article and the article on Vesuvius, it's difficult to imagine the 79 AD eruption (ostensibly a once-every-two-millenia event and a Plinian eruption) is not assigned a VEI in at least one of these articles.

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Could someone who knows about this add a few major well-known eruptions to this page for perspective. For instance, Krakatoa, Mount St. Helens, Pinatubo, whatever. --rmhermen

Krakatoa was a 6, Mount St. Helens a 5.

I added some more "interesting" eruptions. However this list could get really big. I don't think this is the right page for this list. List of volcanoes is also not the right place since volcano and eruption are not the same (many volcanoes on the current list should be on it multiple times). I think there should be a new page list of volcanic eruptions. See also List_of_volcanic_eruption_deaths, Top_10_most_deadly_volcanic_eruptions. Maybe it should be list of largest volcanic eruptions. Jdorje 02:12, 21 May 2005 (UTC)

Honestly making a list by hand is probably not a good use of time. The global volcanism program already has a huge database of eruptions. Simply looking at this list of VEI 4+ eruptions [1] should be intimidating. Looking closely at the information for each eruption you'll see the amount of raw data they have is staggering. Jdorje 04:41, 12 July 2005 (UTC)

I agree that the eruption list is useless. As noted, the The Smithsonian Global Volcanism Program maintains a database of eruptions, constantly updated, for all volcanoes with eruptions in the last 10,000 years. Currently there are more than 9,500 known eruptions from over 1,500 volcanoes. Why try to reproduce any of that by hand when it will be out of date almost immediately? I won't delete it due to a "conflict of interest" though. GVP Webmaster 22:19, 26 December 2006 (UTC)

What about Cosiguina eruption (Nicaragua) of 1835 ? I think it should own a respectable VEI...(didn't it deposit ashes until Mexico/Jamaica/Colombia ?)

Trying to do a list before Holocene. List of large volcanic eruptions --Chris.urs-o (talk) 21:01, 23 March 2010 (UTC)

One reason for including the list is to try to educate readers who have heard of famous/infamous/notorious eruptions but don't have a sense of how big they were relative to one another or what else like them is in the historical record. The statement "the example of a VEI 6 eruption is Krakatoa, and here are the others like it" will inform a reader who's heard of Krakatoa but not Novarupta. That's good, IMO, but it does suggest using "trite" eruptions for each VEI level, and avoiding the ones that are atypical in one way or another. -- Bill-on-the-Hill (talk) 04:41, 8 June 2010 (UTC)

VEI 8

The table in this article states that there has been only one (known) vei 8. However, in the article about supervolcanos about 10 examples are given. Either I'm missing something or one of these articles is mistaken. S Sepp 16:19, Oct 29, 2004 (UTC)

I think what they mean there is that, in human history, only one VEI=8 event, Toba, is known to have occurred. --Golbez 04:12, Dec 29, 2004 (UTC)

What it means is in human lifetime the toba eruption is the only one to have occured. This is wrong Lake Taupo erupted 26,500 years ago erupting over 1,170km3 making it a super-euption also. Also 7 other vei 8 eruptions have happened in the last 30 million years but these were not in human lifetime. The others are stated as supermassive eruptions (VEI7) not super eruptions like Taupo or Toba.

1 and 2

Is the jump between 1 and 2 a mistake? The only authority I see for it is the USGS Glossary illustration which could easily be in error. No acknowledgement appears in the text, which is vague or even contradictory ("Each increase in number represents an increase around a factor of ten. The VEI uses several factors to assign a number", but "[in the figure] Each step increase represents a ten fold increase in the volume of erupted pyroclastic material"—except for #1!). Kwantus 01:24, 2005 Jan 5 (UTC)

Megatonnage?

Several of the articles linked to or from this one mention explosive power in megatonnes. It would seem that adding a column to the table giving ranges would be very useful. Anyone know of such info? Maury 19:25, 10 Apr 2005 (UTC)

I have my doubts about the megatonnage calculation. I don't know the original source -- the 200 megaton number is replicated all over the Web.

I'm uncertain about these numbers. Consider Krakatoa. The amount of energy to lift 10 cubic kilometers of material with a density of 3 gm/cm^3 to a height of 25 km is about 7 x 10^18 J. A megaton of TNT is (somehow) calibrated to be 4.2 x 10^15 J. So, my rough computation is that Krakatoa would be 1600 megatons! Well, maybe not all of the material was lifted all the way to 25 km, but 200 megatons would imply it was lifted an average of 3 kilometers. Maybe we need to divide the plume height by 8, to get an average height?

I hope an expert on computing the energy of volcanic explosions will chime in. -- hike395 20:42, 10 Apr 2005 (UTC)

Making up numbers like that isn't a good idea since there are too many variables for us to take into account. However 7 x 10^18 doesn't seem that high; the 2004 Indian Ocean earthquake is estimated at 2.0×10¹⁸ joules. I'd agree that the measurement of energy would be the most accurate method of assessing a volcano's explosivity, but I have no idea how a volcanologist would go about calculating that. The Moment magnitude scale might be useful here - naively I would assume a VEI 6 volcano would be similar to a magnitude 9 earthquake. Jdorje 02:22, 21 May 2005 (UTC)

A mag 9 earthquake is realeases vastly more energy than a VEI 6 volcano. Estimates for the energy released in the last mag 9 quake (which caused the boxing day tsunami) run at about 4.0×10^22J.

Do not forget that an eruption also release a great amount of energy in the form of heat, and not only mechanical energy.

Problems with VEI

I'm no volcanoligist, but simply trying to explain and categorize existing volcanoes on Wikipedia shows up several major problems with the VEI system. (All numbers below are for the purposes of argument; most are from memory and may not be accurate.)

• Quantization. While earthquakes are measured using a continuous system (to one or two decimal places) most volcanoes explosivity measurements have only one significant digit. This is a major problem when comparing volcanoes of near-equal explosivity that happen to fall on different sides of the boundary, or for very different volcanoes that happen to fall in the same category. For instance Tambora (80-150 km³) was a minimal VEI 7 volcano while Long Valley Caldera (750 km³) was a a very large VEI 7. This is also a problem when there is uncertainty about the eruption size. Consider Santorini (50-200 km³), Taupo (85 km³), and Tambora (80-150 km³). Should Taupo be a VEI 6 while the others are VEI 7, even though Taupo could have been the largest of them? Very rarely I've seen decimal places used in the literature (one source claimed Santorini was a 6.9), but almost all sources stick to integers (sometimes with caveats, like "6-7" or "6+").

• Different measurement techniques. From what I've read, geologists looking at ancient eruptions usually measure in "dense rock equivalent". Thus Toba erupted material equivalent to dense rock of 2800 km³. By comparison modern eruptions are usually measured using whatever scale is handy. Pinatubo erupted 10 km³ and Mount Hudson 6 km³ of ash, but this would be the equivalent of only a small fraction that amount of dense rock. By comparison Laki released 14 km³ of lava (dense rock) and another 12km³ of tephra (mostly ash). Looking at the weight of the ejecta can help in comparisons here, but most sources don't include the weight. It seems obvious that the best solution here is to look at the amount of energy released in the eruption rather than in the amount of rock released (see "megatonnage" discussion).

• Explosivity isn't a good indicator of effects. In many eruptions it's not the explosion itself that causes effects. Pinatubo, Hudson, El Chichon, and (presumably) Tambora and Toba's largest effects were from the release of sulphur dioxide, which may itself not have been at all explosive but had the largest global effects (in particular El Chichon was only a VEI 4 but had a larger global impact than any recent VEI 5 eruptions). This is true of earthquakes as well to some extent - location and type of the earthquake play a big role in how much devastation it causes, as the two recent Sumatran earthquakes have shown - but this isn't really the same thing since earthquakes don't have global or long-lasting impact.

Sulfur dioxide emissions by volcanoes.

I guess my conclusion would be that the VEI measurement is immature, much like the Richter scale measurement was before it. A more advanced measurement would probably give two numbers. An explosivity magnitude would be measured from the energy release of the eruption and could be calibrated either to use the moment magnitude scale or to correspond roughly to the current VEI system. Meanwhile the climate effect value would approximate the global climate effect by measuring the amount/effect of different climate-effecting gasses (SO2, NO2, CO2) that were released by the eruption (see sulfure dioxide figure, right).

Also, I wonder if the problems with the VEI system should be put into the article (the measurement techniques issue is already mentioned).

Jdorje 05:32, 12 July 2005 (UTC)

Power Output

I know little about vulcanology (although I know more now:>), but from what I can determine, the power output of an eruption seems to be a significant measure of volcanic explosivity. The VEI classification does not consider this. I have preemptively added a statement on this issue in the article, but a section detailing the weaknesses of this classification might be better. Opinions?--ChrisJMoor 02:25, 12 Mar 2005

I agree, and have a couple of question. In physics, power is work over time and so is a scalar quantity. Isn't it superfluous to write "magnitude" of power. Why not just "the power output" or something?

At the beginning of the next section, it reads "Scientists indicate how powerful volcanic eruptions are using the VEI." In this section it reads "One weakness of the VEI is that it does not take into account the magnitude of power output of an eruption." Is this not a contradiction? Is there a difference between the "magnitude of power output of an eruption" and how powerful an eruption is? Aliotra (talk) 00:38, 27 March 2009 (UTC)

last-10000-years numbers

These numbers need some sort of disclaimer because they are known to be incomplete. There are 4 VEI7 eruptions, one every 2500 years - the last one happened to be just 200 years ago but this is coincidence. There are 43 VEI6+ eruptions, one every 250 years - but there have been 4 (Tambora, Krakatoa, Katmai, Pinatubo) in the last 200 years alone. Further down the list there have been 4000 VEI2 eruptions - one every 2.5 years - but these are listed as weekly occurrances. My point is just that many/most eruptions of the last 10000 years are not known, particularly for the smaller volcanoes. Someone looking at these numbers expecting to get something out of them will be rather mislead. Jdorje 16:00, 21 September 2005 (UTC)

Is it that evidence of VEI-6 can usually be found, VEI-5 if one looks close enough? For smaller eruptions I guess the number will always be inaccurate, as the evidence is destroyed in later eruptions. —Preceding unsigned comment added by 91.153.52.32 (talk) 04:55, 23 September 2007 (UTC)

They are further inconsistent in other regards. Consider the VEI-2 claim of 3477 occurences. This amounts to roughly thrice a year, but the frequency is given as "weekly".

(In addition, using the 1994 number with that many significant digits today is misleading.) 88.77.182.28 (talk) 19:13, 18 May 2009 (UTC)

VEI literally mean "volcanic Explosive Index" and title is in PAST TENSE. This time-frequency of explosions is referring to "present or future repeation". therefore that column should be removed.216.234.199.125 (talk) 04:46, 23 September 2013 (UTC)

km³ versus m³

someone was asking about these comparisons...1 km³ = (1000 m)³ = 10⁹ m³ = 1 billion m³. — jdorje (talk) 17:52, 9 February 2006 (UTC)

The Fish Canyon Tuff (La Garita Caldera) was not a VEI-9 eruption

Someone has stated that the Fish Canyon Tuff from La Garita Caldera was a VEI-9 eruption and that the volume was 18,000 cubic km. Both are inaccurate. Nowhere in the article [2] does it state that the FC Tuff had a high volume as this. In fact, it's still stated as 5,000 cubic km in that article by Mason et al. [3]. Because the volume erupted is less than 10,000 cubic km, it is still a VEI-8 eruption. If you read the article carefully (see first link in this paragraph), you will notice that "Magnitude" is really a separate scale, and it is important to note that VEI and magnitude measure eruption sizes differently. VEI measures eruption sizes based on volume of magma erupted in cubic km and eruption column height. Magnitude, as used in the article by Mason et al, measures eruption size based on mass of magma erupted in kilograms. NorthernFire 06:10, 26 July 2006 (UTC)

Sorry, that was me. I misread the article. Thanks for fixing my mistake. -- Avenue 08:58, 27 July 2006 (UTC)

There is a valid reason why VEI only attains 8. Anything larger would require the whole Earth. Incidentally someone raised the point why the VEI uses only whole numbers. It doesn't it uses tenths hence a VEI 7.1 is larger than a VEI 7 but only just. The VEI is a measure of just how large an eruption was and like most indicators is subjective to interpretation. Two volcanologists might assign different values to an eruption, but eventually a consensus will be reached. Incidentally if someone wants to link Stephen Self properly to the lead item they might like to try connecting to Stephen Self Volcanology.The Geologist (talk) 13:24, 9 April 2012 (UTC)

Date of Taupo eruption (holocene)

Now what is the exact date of the Taupo eruption, that supposedly caused red sunsets in Rome? I've seen anything from 177 to 186 AD thus far. So what is the latest? I think 177 is, dated via Greenland ice-cores by Zielinski (Science 264 [1994], p. 948f.). I am right? --Bender235 20:14, 13 December 2006 (UTC)

Flood Basalt vs. Tephra

It seems that some Flood Basalt events have been added with very large VEI numbers due to the volume of the products. But the definition at the top of this VEI article says that VEI is based on the volume of Tephra. To the best of my understanding, Tephra is airborne matter whereas a Flood Basalt is floods like a liquid.

So is the definition of VEI wrong in this article, is it an error to include Flood Basalts in the table, or is my understanding in error? -- Cjensen 02:54, 17 January 2007 (UTC)

• It is probably an error to include flood basalts in the manner it was done in this article, thus I've removed the VEI-9-11 info in both tables in the article. Also, the uppermost limit of the VET is apparently 8 according the the Smithsonian Global Volcanism Program (Smithsonian GVP) - there doesn't seem to be any such thing as a VEI 9 or higher. You are correct in that tephra is airborne pulverized volcanic rock. It's really another name for volcanic ash. The VEI is not without its flaws, and I believe they take into account more for explosive eruptions of tephra. Take for example the Eldgjá fissure eruption in Iceland in the year 934 CE. It erupted over 18 km² of basaltic lavaa - the largest known eruption of lava in historical times, yet Eldgjá erupted only 4 km², so it mostly effusive/mildly explosive in nature and was assigned a VEI of 5. In comparison, Krakatoa was over 20km², made mainly of tephra and was assinged a VEI of 6. Speaking of flood basalts, a flood basalt does not just form from a single huge individual eruption of lava. Rather, a flood basalt is made up of hundreds or thousands of individual eruptions of fissure-fed lava flows over a period of several million years, and they would have been mostly effusive, although there is evidence for some fairly large steam-generated eruptions in flood basalts perhaps prior to the actual fountaining of lava as the magma hit groundwater. But many of those individual eruptions of lava in a flood basalt can still be quite huge, generally anywhere from 100 km² to over 2,000 km² - about the same volume range for large caldera-forming eruptions like Yellowstone 640,000 years ago. The only difference is the kind of magma that comes out. NorthernFire 22:19, 21 January 2007 (UTC)

I Agree maybe a new system is needed so that it judges both tephra and basalt eruptions. Wiki236 14:19 25 January 2007 (UTC)

Looking at Grímsvötn it looks like a basalt flow eruption in 1783-1785, but a tephra eruption in 8230 BCE ± 50 - both look to have been described as VEI 6. However basalt flow doesn't seem explosive to me - perhaps one of those eruptions should have a different VEI listing? EdwardLane (talk) 10:44, 23 May 2011 (UTC)

As I understand it VEI is just described based on total tephra, with basalt volumes only being being included under Dense rock equivalent so it should be possible to look at the VEI and the DRE of an eruption - and take the proportion of DRE that is included in VEI to give some characteristic of the effusive/explosive nature of the eruption - with DRE giving some idea of scale. Interesting that VEI has the volume required to rate volcano in order of magnitude or tephra but the DRE article does not have the equivalent DREindex. EdwardLane (talk) 10:30, 7 June 2011 (UTC)

Tenerife

Does anyone know if the Caldera on the Island of Tenerife (Las Cañadas) is a supervolcano or not?. All I know is that it was most likely created in a VEI 7 explosion 150,000 years ago, could anyone help me out? Wiki235 18:15 31 January 2007

No, it was not. See supervolcano. Guanlongwucaii (talk) 09:46, 27 May 2009 (UTC)Guanlongwucaii

As a geologist / volcanologist working and living on Tenerife, I can assure you that the Las Canadas caldera was not formed in an eruption 150 ka, but as a series of edifice failures - these being the Ucanca caldera (oldest), Guajara caldera (younger) and the Diego Hernandez about 150 ka. El Teide is the Las Canadas IV volcano. There are several papers and books dealing with the formation of the Las Canadas caldera. There are various physical reasons why the caldera was not formed in one cataclysmic eruption. The estimate of the VEI is about 5 for all eruptions of the Las Canadas volcanoes. By the way does anyone know how to add accents? as the "N" in Canadas should have an accent like a tilde over it. Thanks.The Geologist (talk) 13:33, 9 April 2012 (UTC)

Discontinuity between VEI 0 and 1

This topic had already been mentioned some time ago, and maybe a solution has been found meanwhile (but not mentioned in the article). There is a discontinuity in the amount of ejecta that increases by a factor of 100 between VEI 0 and 1, but by a factor of 10 in the rest of the table. Apparently, this table (and probably most of, if not all other VEI-related web sites) is based on this USGS page. As can be seen there, this discontinuity could easily be caused ba a simple misprint in the labels within the diagram since it is never mentioned elsewhere. If this discontinuity is a feature, what is the reason for it? Since this discontinuity is obvious, it should be mentioned in the article (at least the fact, that the reason is unknown).--SiriusB 08:51, 29 May 2007 (UTC)

The original paper proposing the scale (Newhall and Self, 1982) is cited in both our article and the USGS page you linked. It would probably be the best place to look for a reason for the discontinuity. I agree it would be useful to at least note the jump in our article. -- Avenue 14:22, 29 May 2007 (UTC)

Unfortunately, I have no access to this paper (probably there is no scanned version online according to the ADS). If anybody has access to it via a library of a geological institute or so, it would be nice if he or she could have a look into it. Meanwhily the USGS page appears to be the only public source, and therefore the possibility of a simple misprint in the figure (as fas as I can see it is the only source for all public available data including this WP article) is not ruled out.--SiriusB 12:41, 5 June 2007 (UTC)

It is not the only online source. For example, the tables in this definition from the Smithsonian Institution give the same cutoff, twice. I don't think the suggestion that it's an error has any credibility, and I've deleted it from the article. -- Avenue 03:22, 6 June 2007 (UTC)

However, I cannot see any explanation for this discontinuity, and unless one of us gets access to the Newhall C G, and Self S (1982) paper (which seems to be the origin of the table) we cannot rule out the possibility of an error (errors of this kind happen much more often even in fully refereed papers than most people think). I think that this discontinuity is so striking that an error seems to be more probable than a real feature (that otherwise would have been discussed somewhere). On the other hand, if it is intentional then it casts doubts on the usefulness of such a definition of the VEI unless explained plausibly (not only in a non-free paper but also on the public web pages). Therefore I suggest to mention this possibility in the article.--SiriusB 17:21, 7 June 2007 (UTC)

Personally, it doesn't surprise me that smaller eruptions would be treated differently by the scale, but that is not the issue. Discussing your personal speculations about possible scale errors in our article is not appropriate. Please do not add them unless you can provide an external source mentioning at least the possibility of an error. -- Avenue 22:29, 7 June 2007 (UTC)

Unfortunately, the Newhall/Self 1982 article is not available online (even to university subscribers), so I'll just go and photocopy it from the library tonight. But I think it's likely that the factor of 100 was done intentionally so that VEI 0 would contain only non-explosive eruptions. Incidentally, I think the table at Volcanic Explosivity Index#Classification may have an error, in that the VEI 0 ejecta volume should say "<10,000 m³" instead of ">1,000 m³". This is what both USGS and GVP imply. But I'll wait to make any changes until after reading the original paper. --Seattle Skier (talk) 22:49, 7 June 2007 (UTC)

Well, I photocopied the Newhall/Self 1982 article (BTW, the reference to it was wrong, now fixed), and I have read through it twice. The VEI scale is now correctly presented in the article: VEI 0 is < 10,000 m³, while VEI 1 is between 10,000 m³ and 1,000,000 m³. The paper provides no explanation for this, but the authors spend much time and effort discussing the approximate nature of the scale and the difficulty of categorizing eruptions below VEI 2. So it appears likely that this extra order of magnitude was done simply to ensure that truly non-explosive eruptions would fall definitely into VEI 0, while the extra-broad VEI 1 classification could accomodate all borderline exposive eruptions (that's my own opinion based on reading the paper). I don't think there's any legal way to post the Newhall/Self 1982 article online, so others will have to track it down in their local university library and draw their own conclusions, if they wish to do so. --Seattle Skier (talk) 06:46, 8 June 2007 (UTC)

The Newhall and Self paper is available at this address: Newhall, Christopher G.; Self, Stephen (1982). "The Volcanic Explosivity Index (VEI): An Estimate of Explosive Magnitude for Historical Volcanism" (PDF). Journal of Geophysical Research 87 (C2): 1231–1238. Bibcode:1982JGR....87.1231N. doi:10.1029/JC087iC02p01231. Yes it does work if you go back to the article and click on it in "References."The Geologist (talk) 16:46, 21 December 2013 (UTC)

VEI-9

Shouldn't the article mention VEI-9? 70.51.9.197 05:28, 13 August 2007 (UTC)

No. There is no 9 on the scale. — jdorje (talk) 23:04, 25 September 2007 (UTC)

Yes. The scale is theoretically open-ended, just because there haven't been any confirmed VEI-9 eruptions on Earth so far doesn't mean that there won't be in the future. Newhall and Self (1982) 131.111.195.11 (talk) 21:07, 31 October 2008 (UTC)

Huh? La Garita is VEI 9.3 (see source). ~AH1^(TCU) 19:54, 8 November 2008 (UTC)

I think I know where you're getting the "VEI 9.3" from. You stated that you mentionend a couple of sources stating such a magnitude, but what happened was that a couple of years ago, I did come across what was probably one of the scientific papers you mentioned. I remember that it was apparent that whoever wrote the paper was using a different scaling system to measure the scale of volcanic eruptions, even though the VEI was mentioned. Their own scaling system was taking into account the mass erupted in kg - something that the VEI doesn't appear take into account. I mentioned the discrepancy in the La Garita article's discussion page at that time as well. I do, however, have to agree that the VEI scale as used by the Smithsonian Global Volcanism Program (GVP) is in theory open-ended, even though goes only up to 8 (see the following link: http://www.volcano.si.edu/world/eruptioncriteria.cfm#VEI). A VEI of 8 would denote a volume of at least 1,000 cu. km. The next step up (VEI-9) would be over 10,000 cu. km, because the VEI is a logarithmic scale in terms of volume erupted. But, while La Garita Caldera is the largest known eruption to have occurred on the face of the planet, the largest individual eruption (Fish Canyon Tuff, about 27.8 million yrs ago) is not known to exceed ~5,000-6,000 cubic km. There are no known eruptions which have occurred on this planet to have erupted a magma volume of over 10,000 cubic km - yet. As huge an eruption it was, La Garita would still be in the VEI-8 range. NorthernFire (talk) 23:09, 8 November 2008 (UTC)

Having read the source that supposedly supports La Garita being "VEI 9.3" I can assure you that that term is used nowhere in the paper. The source discusses 47 VEI 8 erruptions including La Garita and assesses them against a magnitude scale of their own device which is not the VEI scale for which they use the letter M. --LiamE (talk) 06:31, 16 November 2008 (UTC)

I have read the article too and agree with number 5 [LiamE's comment - the numbers are now removed]. there is no mention. it is also not an open ended scale. 20:39, 23 March 2010 97.84.3.89

Quote: "The open-ended VEI scale applies only to explosive eruptions, with the VEI value determined primarily by the volume of eruptive products, height of the eruption cloud, and eruption duration, but with qualitative observations of explosivity (e.g., “gentle,” “cataclysmic,” “colossal”) also considered." Tilling, R. I. (14 December 2009). "Volcanism and associated hazards: the Andean perspective" (PDF). Advances in Geosciences (22): 125–137. Retrieved 2010-03-16. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help) --Chris.urs-o (talk) 20:51, 23 March 2010 (UTC)

Eruption count

According to the cited Global Volcanism Program page, no VEI-8 or "super-eruption" has occured in the past 10,000 years (which the table says it lists when it give 1 for VEI-8). The most recent eruption of that size was the Lake Taupo event around the end of the Last Ice Age 26,000 years ago. I think that whole erution count given for each category may need to be reassessed. -- §HurricaneERICarchive 03:00, 23 December 2007 (UTC)

Santorini

Hasn't Thera(Santorini) been reconsidered as a VEI 7 volcano?.

--Triou —Preceding unsigned comment added by Triou (talk • contribs) 23:00, 20 March 2008 (UTC)

Isn't that still a bit uncertain? The Smithsonian database says the Minoan eruption was "7?" on the VEI scale; this site reports it as 6.9. I'd be happy to see sources that confirm it. -- Avenue (talk) 13:08, 21 March 2008 (UTC)

The highest estimations for the Minoan eruption are 70 km³ tephra, which is still VEI-6 (a large one, tho). However, 30 km³ tephra is more likely. --Bender235 (talk) 19:31, 24 April 2008 (UTC)

VEI 9 and 10

Since the VEI is actually "open end", we might add a 9 and 10 on the scale, since there have been eruptions of the magnitude: Deccan Traps (VEI 9), Emeishan Traps (VEI 9) and Siberian Traps (VEI 10). ––Bender235 (talk) 19:31, 24 April 2008 (UTC)

None of those were formed in a single explosive eruption, so the VEI doesn't apply. -- Avenue (talk) 01:23, 25 April 2008 (UTC)

Even if they did form in a single eruption, none of those eruptions appear to be explosive; they're flood basalts. Black Tusk 01:40, 30 April 2008 (UTC)

Before saying should "we" add effusive eruptions such as the Deccan Traps and Siberian Traps "you" need to consider what the term "VEI" means. There is a BIG clue as to why effusive eruptions are NOT included the term VEI stands for "Volcanic EXPLOSIVE Index." Effusive eruptions are by definition NOT explosive, even if they erupt fire fountains of lava.The Geologist (talk) 16:51, 21 December 2013 (UTC)

Ok if there was a 10,000 would we be able to add VEI9 in? im asking because there seems to be one with 12,000 in canada and it was not a effusive eruption and it was for sure a super eruption , and for sure less then a million years still no 100% proof it was 1 or multiple but what do we do about this canadian supervolcano? https://en.wikipedia.org/wiki/Flat_Landing_Brook_Formation Joshoctober16 (talk) 03:25, 30 September 2019 (UTC)

@Joshoctober16: the 12,000 km³ (2,900 cu mi) volume given in the Flat Land Brook Formation article is a combination of both pyroclastic rocks and lava flows, the latter of which VEI excludes. There is also the question on whether or not the formation is a product of one massive eruption or multiple smaller eruptions. Volcanoguy 03:49, 30 September 2019 (UTC)

Classification table

If VEI is defined by volume of ejecta could we move that column left to be column 2 ? Rod57 (talk) 22:00, 27 November 2008 (UTC)

Thanks, that's a good idea. I've done it. -- Avenue (talk) 11:31, 26 May 2009 (UTC)

Something wrong with display units in figure

The figure describing VEI displays volumes with units of area, yet when you click on the diagram the enlarged diagram shows the correct volume units. RStillwater (talk) 15:14, 8 December 2008 (UTC)

I see what you mean. If you look closely, the superscripts don't quite look like twos either - they are actually threes that were being shrunk so small that they looked more like twos than threes. This problem seems to have arisen when someone converted it to vector format in April 2008; the original used a larger font size for the threes. I've done the same, and tidied up some other minor problems. It could still use some revision to make it less US-centric, though. -- Avenue (talk) 11:12, 26 May 2009 (UTC)

Non-Earth comparisons?

Would there be any value in including examples of directly-measured or estimated volcanic explosions from elsewhere in the solar system, e.g. Io or Mars, to illustrate the magnitude of eruptions there, as compared to on Earth? Io_(moon)#Volcanism Careful With That Axe, Eugene (talk) 15:58, 5 May 2009 (UTC)

Eyjafjallajökull

If I'm right. Europe's air traffic was disrupted by a VEI 2 eruption. Ok. The article states VEI 4, but the VEI is not fixed yet !!! Quote: "A firm number won't be assigned for some time, but so far, about 110 million cubic meters of tephra have been ejected during this eruption, and the plume has gone about nine kilometers into the air, so that’s a VEI of 4." (Hendry, Erica R. "What We Know From the Icelandic Volcano". Smithsonian (magazine). Retrieved 22 April 2010. {{cite web}}: Check date values in: |accessdate= (help)) --Chris.urs-o (talk) 06:55, 11 June 2010 (UTC)

I've also heard VEI 2, and in any case that eruption was clearly not a hugely powerful one - something the media largely failed to bring out, because the circumstances and the effects on air travel were so unusual. Most volcanoes do not produce ash with that kind of insidious effect on jet engines even when the ash is spread out in low concentrations - that was what happened with E-jökull, and it's dependent on the local geological circumstances.

And of course, the eruption didn't have that great explosive power - nothing like Mount Pelée, which is classed together with it here on level 4. Pelée was infinitely more violent. Now, the VEI index doesn't account for the force of the eruption in its peak stage, or for the amount of heat generated (which is linked to the explosive force), only for the volume of tephra blown out. I still think 4 sounds too high, and this should be checked with other assessments - the Smithsonian Project is not God, and some of their assessments are educated guesses.Strausszek (talk) 00:08, 14 September 2011 (UTC)

The reason that the Eyjafjallajökull was assigned a VEI 4 is simple. It started life as a strombolian eruption, but the melt waters from the glacier fragmented the lava and increased the amount of tephra flung into the sky. It was essentially a strombolian eruption which underwent a phreatomagmatic stage bordering on the vulcanian.The Geologist (talk) 16:55, 21 December 2013 (UTC)

Soufriere Hills

It is not a VEI 4 - See http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05=&volpage=erupt

Guanlongwucaii (talk) 09:46, 27 May 2009 (UTC)Guanlongwucaii

Deletion discussion of Category:Volcanoes_by_Volcanic_Explosivity_Index

Editors interested in Volcanic Explosivity Index may be interested in contributing at Wikipedia:Categories_for_discussion/Log/2010_April_22#Category:Volcanoes_by_Volcanic_Explosivity_Index. --SmokeyJoe (talk) 01:24, 22 April 2010 (UTC)

Date of Taupo

The VEI table says 24.5k years ago. The paragraph immediately underneath says the most recent VEI 8 eruption was Taupo 26.5k years ago (which corresponds with the actual eruption page). I'm assuming it should be 26.5k but any thoughts? — Preceding unsigned comment added by 82.196.43.45 (talk) 12:31, 19 March 2014 (UTC)

A difference of 2,000 years usually indicates some confusion between BC and BP. Our table says 24,500 BP, which is consistent with the date of 26,500 years ago mentioned in the text, so that all seems okay. The Toba date seems a bit more suspect: the table says 74,000 BC, but the linked article says 73000±4000 years BP. At least the inconsistency is smaller than the error range quoted. --Avenue (talk) 10:58, 20 March 2014 (UTC)

English prospectus and the Italian one does not match

English prospectus and the Italian one does not match. Mormegil 87.18.198.92 (talk) 16:49, 23 June 2013 (UTC)

Use of Ma

Ma is presumably Mega Annum or a million years. If this is correct then the units should be shown as Ma BP. Any views? treesmill (talk) 13:53, 12 May 2010 (UTC)

"ago may not always be mentioned; if the quantity is specified while not explicitly discussing a duration, one can assume that "ago" is implied; the alternative but deprecated "mya" unit includes "ago" explicitly" Annum#SI prefix multipliers, wiktionary:annum, the references do not use ago at all, sorry. --Chris.urs-o (talk) 14:19, 12 May 2010 (UTC)

some interesting stuff?

This [4] looks like it has some extra info that could be used to expand the VEI article. EdwardLane (talk) 10:44, 7 June 2011 (UTC)

Go ahead an be bold. By the way, don't mark your Talk Page edits as 'minor' as other user's watch pages often ignore minor edits. Careful With That Axe, Eugene ^Hello... 11:45, 8 June 2011 (UTC)

Thanks - I might get around to being bold (I don't generally have a problem with that) but I'm not sure I'm expert enough, but I'm gradually getting my head around the specifics of vei, this and the original comment got a 'minor' tag as it wasn't anything bold - perhaps I need to reassess when to tag as minor. Thanks EdwardLane (talk) 11:46, 9 June 2011 (UTC)

VEI 8 every 10.000 years?

Hey, I was looking at the table and it says that VEI8 eruptions happen every 10.000 years, however another article states that these events happen every 50.000 - 100.000 years.

Also, isn't there a VEI9? — Preceding unsigned comment added by 186.28.14.104 (talk) 02:21, 1 January 2012 (UTC)

As far as we know, there is no currently discovered deposit of material that allows for a VEI 9 eruption. Even though it's perfectly rational that a VEI 9 eruption may happen, until one does or evidence of one is found, we can't add it to the article unfortunately.

As for the original question, if the evidence used for the articles are different, then the estimations of time-scales between events may be different. The second estimation would seem more correct, if we consider the last VEI 8 event known to have occurred, was Lake Taupo's Oruanui Eruption 26,500 years ago. Before that, it was the YTT approximately 74,000 years ago. This is roughly a time-scale of 50,000 years between these kind of events and thus it would more likely that the second estimation is correct.

However, more evidence than this will be needed because, of course, at some points in the geological record, there will have been much bigger gaps between VEI 8 events and at some points, much smaller gaps between events, maybe even a few thousand years. What people fail to understand about volcanoes and in particular these types of events, is that they aren't working on a timer, or a schedule. They will erupt when the conditions that allow them to are present, and this may not work in a cycle, despite what the media may tell you. It may be 1 million years before the next VEI 8 event occurs, or it may happen in the next 10 seconds. The fact is, a volcano will erupt when there is enough magma and a fracture route exists between the magma and the surface. Sometimes these conditions form in cycle-like periods of time and at other times not. In any case if you can find a scientific article or journal to provide the solid evidence needed to back your hypothesis up, then by all means change the article. Wiki235 (talk) 17:55, 5 April 2012 (UTC)

Requested move

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: no consensus. Jenks24 (talk) 10:22, 10 June 2014 (UTC)

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Volcanic Explosivity Index → Volcanic explosivity index – Not a proper name; the cited sources (other than the deadlink one) use lower case, as do many others. --Relisted. Armbrust ^{The Homunculus} 13:56, 27 May 2014 (UTC) Dicklyon (talk) 01:56, 20 May 2014 (UTC)

• Disagree - the USGS glossary link (under 'External links') has initial caps in its definition. Although the link to the Smithsonian's GVP site's VEI definition page is now a deadlink - it seems that it wasn't reinstated after the website was substantially rebuilt some time ago (despite my later request to them, as a WP editor!) - the GVP website still uses initial caps, e.g. see under the "Eruptive History" tab for individual volcanoes in their online database. Cheers, Bahudhara (talk) 03:03, 20 May 2014 (UTC)

The glossary heading is in title case, but the same page has it lower case later. Dicklyon (talk) 04:14, 22 May 2014 (UTC)

• Weak Support - I'm a little confused as to the difference between a proper and improper names, but Wikipedia:Naming conventions (capitalization) seems pretty clear here. Plus, there is plenty of other stuff to look at, including Consumer price index. NickCT (talk) 16:44, 27 May 2014 (UTC)

There are many consumer price indices, e.g. they can be compiled for each country, state, even city, or for different time periods - however, there is only one VEI - it is unique. Cheers, Bahudhara (talk) 08:17, 1 June 2014 (UTC)

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The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Rename

I see someone moved the title of this article from Volcanic Explosivity Index to volcanic explosivity index awhile back, which in my opinion is incorrect. A quick google search shows that the VEI is normally capitalized. I suggest the article title be moved back to its original form. Volcanoguy 07:22, 28 April 2016 (UTC)

The subject of this article (Volcanic explosivity index) is the Volcanic Explosivity Index. There is only one index with this name. I'm not an expert in English grammar but I think this index is a proper noun, more strictly a proper name, similar to e.g. North America (which we do not write as North america). I think all three words of Volcanic Explosivity Index should start with a capital/uppercase letter.

Some of the sources that give initial capital/uppercase letters to all three words in the name of the Volcano Explosivity Index:

• the creators of the index (Newhall and Self, 1982)
• the US Geological Survey
• the Smithsonian Institution's Global Volcanism Program
• the Geological Society of London's Working Group on Super-eruptions
• Oregon State University's Volcano World website

A volcanic eruption is given a specific index value (VEI 0 to 8) from the Volcanic Explosivity Index. Unfortunately and confusingly, this assigned value is called its volcanic explosivity index but this specific number is only a volcanic explosivity index, which I think is a common noun and this should be entirely in lower case.

I recommend that this article should be renamed to "Volcanic Explosivity Index" with a redirect from "Volcanic explosivity index". GeoWriter (talk) 15:17, 24 August 2016 (UTC)

• Strong support - see my argument in the 2014 discussion above. Bahudhara (talk) 23:57, 24 August 2016 (UTC)

Even though it was pointed out in that discussion that your argument there was incorrect? Dicklyon (talk) 07:18, 4 January 2017 (UTC)

• @GeoWriter and Bahudhara: Went ahead and did the move. Volcanoguy 12:54, 14 September 2016 (UTC)

possible VEI 9

https://en.wikipedia.org/wiki/Flat_Landing_Brook_Formation#cite_note-QB-3

a supervolcano said to be one of of the largest eruption on the planet , in eastern canada this might be one to add for a VEI9? — Preceding unsigned comment added by Joshoctober16 (talk • contribs) 05:18, 15 December 2017 (UTC)

The page doesn't say all 12000 km³ of it occurred in one eruption. At least 10000 km³ has to have come from a single explosive eruption in order to qualify for VEI 9. Given that this appears to be a nonexplosive flow complex, it doesn't count.--Jasper Deng (talk) 06:11, 15 December 2017 (UTC)

There is also no such thing as "VEI-9". It only extends from VEI-0 to VEI-8. Volcanoguy 22:03, 20 June 2018 (UTC)

@Volcanoguy: Technically, the scale has no upper bound (see older discussions on this page); however, no VEI-9 eruptions have ever been recorded.--Jasper Deng (talk) 06:50, 24 September 2018 (UTC)

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