Gallery: Heavy Hitters of Holocene Volcanism
01avachinsky-russia
So, over the last few weeks, I've been learning how to use R, a software package that does statistical analyses and data plotting (and more). Rather than using the data sets that are included in the software to learn how to make it do what I want it to do, I thought it would be more fun to look at a decently sized data set that might be of more interest to me. So, I downloaded the [Global Volcanism Program's list of large Holocene\* eruptions](http://www.volcano.si.edu/world/largeeruptions.cfm) (defined as [VEI](http://volcanoes.usgs.gov/images/pglossary/vei.php) of 4 or greater) and have been using that as a testbed for my new R skills. One of the first things I did was compile a count of how many times each volcano shows up in the large Holocene eruptions list - sort of a quick assay of what are the most active volcanoes. Well, maybe not the *most active* - there are many volcanoes that have erupted frequently over the last 10,000 years before at VEI of less than 4. [Kilauea](http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01-) is a good example of this, as it is very active, but only shows up a couple times in the large Holocene eruption list. This list is something like "most large eruptions from a single volcano" list. Now, as with any list like this, we're biased towards (a) more recent eruptions that appear in the historic record and (b) volcanoes that are not in remote locations. There may well be other large [Holocene](http://www.ucmp.berkeley.edu/quaternary/holocene.php) eruptions that we haven't identified or have misidentified (see my discussion of the [missing eruption of 1258](http://stag-komodo.wired.com/wiredscience/2012/02/the-mysterious-missing-eruption-of-1258-a-d/)). So, this list becomes "most large eruptions from a single volcano that we know of." Bit of a mouthful, so instead let's just call it "the heavy hitters of Holocene volcanism." \* The [Holocene Epoch](http://www.ucmp.berkeley.edu/quaternary/holocene.php) is roughly the last 10,000 years. There is some discussion of whether the Holocene is over and we're now into what some people call the [Anthropocene](http://www.nytimes.com/2011/02/28/opinion/28mon4.html?_r=0). \#10 Avachinsky (12 entries) ============================ Interestingly, the top 10 on the GVP list are also the only volcanoes that appear on the list in double digits. [Avachinsky](http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-10=) is located on the Kamchatka Peninsula in Russia - our #1 region for Holocene volcanism, with over 100 entries. We haven't seen an eruption of Avachinsky since 2001, but it might be the most hazardous volcano on the peninsula due to its proximity to Petropavlovsk. In the NASA EO image (above), you can see both Avachinsky, with its large, breached caldera and Kozelsky, which has grown on the side of the older volcano. *Image: [NASA Earth Observatory](http://earthobservatory.nasa.gov/IOTD/view.php?id=50602).*
02vesuvius-italy
\#9 Vesuvius (13 entries) ========================= Not a big surprise to many, [Vesuvius](http://www.volcano.si.edu/world/volcano.cfm?vnum=0101-02=) is actually the only Italian volcano to make the top 10 (Etna, although with frequent eruptions, tends to be less explosive, so only lands at #54 with 3 entries). We've been waiting since 1944 for another eruption of the large arc volcano and many people would consider Vesuvius to be the most dangerous volcano on Earth, with suburbs of Naples creeping up and around the edifice (see above). *Image: [NASA Earth Observatory](http://earthobservatory.nasa.gov/IOTD/view.php?id=6403).*
03taupo-new-zealand
__\#6 (tie) Taupo, New Zealand (15 entries) -__ [Taupo](http://www.volcano.si.edu/world/volcano.cfm?vnum=0401-07=) is remarkable for its magmatic productivity. Even if you don't look at its last 10,000 years of activity, it would still be a beast after the [Oruanui eruption](http://petrology.oxfordjournals.org/content/47/1/35.full) (~26,500 years ago) that produced over 1,100 cubic kilometers of volcanic debris. During the Holocene, it has had numerous huge eruptions, including the famed 186 A.D. eruption that may have been one of the [few ultraplinian eruptions](http://www.sciencedirect.com/science/article/pii/0377027380900086) of the Holocene. It is hard to capture the scale of Taupo from the ground, and this picture I took in 2009 (above) just shows some of the caldera lake and low, sloping hills made of volcanic deposits that surround the giant volcano. *Image: Erik Klemetti*
04ibusuki-volcanic-field-japan
\#6 (tie) Ibusuki Volcanic Field, Japan (15 entries) ==================================================== If ever you wanted a dark horse for this list, [Ibusuki](http://www.volcano.si.edu/world/volcano.cfm?vnum=0802-07=) would be it. I had to look up the volcanic field to even know where in Japan it lies, but it has been prolific over the Holocene. It might be a little unfair that this whole system, that includes a caldera, stratocones and a multitude of maars and craters, would be considered a single volcano on the list. However, this volcanic field on Kyushu has been active, produced the caldera only 4,600 years ago. However, since ~886 A.D., Ibusuki has been quiet - the second longest period of quiescence of any volcano on the list (after Taupo). *Image: [Ray\_Go / Wikimedia Commons](http://commons.wikimedia.org/wiki/File:Ibusuki_Volcanoes.jpg)*
05hekla-iceland
\#6 (tie) Hekla, Iceland (15 entries) ===================================== The first of two Icelandic volcanoes on the list, [Hekla](http://www.volcano.si.edu/world/volcano.cfm?vnum=1702-07=), last erupted only 12 years ago. It erupts a different composition magma than other Icelandic volcanoes - its basaltic andesite to andesite is more viscous than the standard basalt, which could account for some of its explosivity. However, with most Icelandic volcanoes, the amount access to water (in the form of ice and snow) likely help with the explosive eruptions as well. It's last VEI 4 or greater eruption was in 1947 and [much of Icelandic is covered](http://www.decadevolcano.net/volcanoes/iceland/hekla.htm) with layers of tephra from other, older eruptions from the volcano. *Image: [Ken Chen / Flickr](http://www.flickr.com/photos/kenchen/4020734415/)*
06arenal-costa-rica
\#5 Arenal, Costa Rica (19 entries) =================================== We head to Central America as we enter the top 5 - Costa Rica's [Arenal](http://www.volcano.si.edu/world/volcano.cfm?vnum=1405-033). The behavior of this highly active volcano is one of explosive eruptions followed by periods of lava flows that build the edifice as we see it. This includes the most recently period of active (which may have ended in 2010) that started with a VEI 3 eruption in 1968. However, tephra layers found across Costa Rica attest to the large explosive eruptions that recurred every few hundred years, with the last occurring around 1400 A.D. *Image: [Isaac Bordas / Flickr](http://www.flickr.com/photos/norimaki/2373789205/)*
07katla-iceland
\#3 (tie) Katla, Iceland (21 entries) ===================================== Our second Icelandic volcano is the volcano that strikes fear in hearts of journalists everywhere (or so it seems), [Katla](http://www.volcano.si.edu/world/volcano.cfm?vnum=1702-03=&volpage=erupt). Located on the southern side of the island nation, Katla is the first volcano with over 20 entries in the list and it erupts the full spectrum of magma - basalt to rhyolite. This likely aides in producing explosive eruptions as the hot basaltic magma mixes with cooler rhyolite mush that accumulates under the volcano. Katla produced two VEI 4+ eruptions within 60 years of each other in 1860 and 1918 and a VEI 5 in 1755, so the threat of a large eruption is there. However, as an active volcano with a glacier perched on top, you should expect a lot of earthquakes even in an eruption isn't in the cards, so don't get too jumpy. *Image: [Edward and Caroline / Flickr](http://www.flickr.com/photos/edwardandcaroline/7370022230/)*
08cotopaxi-ecuador
\#3 (tie) Cotopaxi, Ecuador (21 entries) ======================================== South America's lone representative in the top 10, [Cotopaxi](http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-05=) looms over central Ecuador. Eruptions from Cotopaxi can be quite impressive, with some lahars from the volcano having thought to have traveled 100 km from the source. You would think that a volcano like Cotopaxi would have all of its modern eruptions well documented, but the VEI 3 eruption in 1942 is listed as "uncertain" in the GVP database as unsubstantiated press reports are the only evidence of this eruption. *Image: [Bertrand Semelet / Camp to Camp](http://www.camptocamp.org/images/250889/fr/cratere-sommital-du-cotopaxi)*
09pelee-martinique
\#2 Pelée, Martinique (22 entries) ================================== [Pelée](http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-12=) is not only appears the second-most times in the list, but it also produced the deadliest eruption of the 20th century. The [1902 eruption](http://www.geology.sdsu.edu/how_volcanoes_work/Pelee.html) produced a pyroclastic flow that destroyed St. Pierre, killing over 30,000 people. VEI 4 or larger eruptions have been common at Pelée over the last 10,000 years, as the sticky andesite lavas that eruption from the volcano form domes and plugs that collapse, releasing pressure and producing an explosive eruption - the [Peléean style](http://publishing.cdlib.org/ucpressebooks/view?docId=ft6v19p151&chunk.id=d0e10328&toc.id=d0e10035&brand=ucpress) of eruption. *Image: [Kenshiraw / Flickr](http://www.flickr.com/photos/30073994@N05/2818631338/)*
10shiveluch-russia-3
\#1 Shiveluch, Russia (43 entries) ================================== In a sense, Shiveluch is like the Babe Ruth, the Pele, the Michael Jordan, of Holocene volcanoes. Other volcanoes will erupt, but Shiveluch is so far ahead that catching up would be quite a feat. Coming in at almost double the number of entries of the #2 volcano, Shiveluch has been incredibly productive during the Holocene. Much like Pelée, Shiveluch is characterized by dome-collapse eruptions that produce pyroclastic flows, ash fall and lahars. The NASA Earth Observatory image (above) captures one of Shiveluch's many 2012 eruptions, this one relatively small, that sent ash out over the Pacific Ocean. So, any surprises on the list? Any volcanoes you thought would make the top 10 and didn't? I find it interesting how some of the volcanoes are frequently active with punctuated massive eruptions (Shiveluch, Arenal) but, as we might expect, many have longer repose periods between sizable eruptions. If you're curious, some honorable mentions, knocking at the door of the top 10 include [Raoul Island](http://www.volcano.si.edu/world/volcano.cfm?vnum=0402-03=), [Cerro Bravo](http://www.volcano.si.edu/world/volcano.cfm?vnum=1501-012), [Colima](http://www.volcano.si.edu/world/volcano.cfm?vnum=1401-04=), [Fuego](http://www.volcano.si.edu/world/volcano.cfm?vnum=1402-09=), [St. Helens](http://www.volcano.si.edu/world/volcano.cfm?vnum=1201-05-) and [Ksudach](http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-05=). *Image: [NASA Earth Observatory](http://earthobservatory.nasa.gov/IOTD/view.php?id=79353)*
