2012: A Volcanically Quiet Year (So Far)

A brief explosion from Popocatépetl in Mexico on July 21, 2012. Popo has been one of the few volcanic newsmakers of the year. Webcam capture courtesy of CENAPRED.

One topic of discussion that has come up recently on Eruptions is how volcanically quiet 2012 has been so far. Unlike the last few years where there have been multiple significant eruptions that captured people’s attention, there have not been many such events in the past 7 months. Now, this is not to say that there hasn’t been volcanic activity – there has been plenty. However, we have not seen any large eruption that has been splashed across the media since Puyehue-Cordón Caulle  last fall … and not to tempt fate, but it was noted on Twitter last night that there hasn’t been a M7 or greater earthquake since April on the planet. We still have 5 months to go, but so far 2012 has been turning out to the the opposite of the Mayan apocalypse that some people are expecting.

However, is 2012 anomalous? Hardly! Just like when there is a strong uptick in volcanic/earthquake activity, this lull is likely mainly due to the random distribution of volcanic events. Sometimes we get clusters of larger eruptions, sometimes we get quiet times. One quick way to look at this is to think about the number of VEI 4 or greater eruptions over the past 10 years (as a small sampling):

• 2012: 0
• 2011: 3* (Puyehue-Cordón Caulle, Grímsvötn, Nabro)
• 2010: 2 (Eyjafjallajökull, Merapi)
• 2009: 1 (Sarychev Peak)
• 2008: 3 (Kasatochi, Okmok, Chaiten)
• 2007: 0
• 2006: 1 (Rabaul)
• 2005: 1 (Manam)
• 2004: 0
• 2003: 0
• 2002: 2 (Reventador, Ruang)

* Note: The estimated eruptive volumes for some of the major eruptions of 2011 are not well quantified due to their location (amongst other things). Puyehue-Cordón Caulle was clearly VEI 4+, but Nabro and Grímsvötn are, at the most, VEI 4, likely below that threshhold of 0.1 cubic km of erupted material.

So far in 2012, no eruption reaches anywhere close to the VEI 4 mark, with the most activity centered around the ever-active volcanoes such as those in the Kamchatka Peninsula (especially Karymsky, Kizimen and Shiveluch), Sakurajima, Kilauea and Santa Maria. New arrivals such as Popocatépetl and Nevado del Ruiz, have only produced minor explosions while some rumbling volcanoes such as Iliamna and Rincón de la Vieja have yet to do much of anything at all. This is all normal for the volcanoes of Earth – sometimes they have a busy years with large eruptions like in 2011 or 2008. Sometimes there are none of the larger eruptions that capture everyone’s attention, but volcanism marches on in the form of smaller eruptions that keep that heat circulating from the interior of the Earth to the surface. In the past, this might have been explained by missing data – it was surprisingly easy to “hide” an eruption – but with the increased monitoring, especially through seismic stations worldwide and satellite imagery, it is hard to imagine a large eruption going on unnoticed on Earth**.

Like I said, 2012 still has 5 months to go, so all this talk of a “quiet” volcanic year might be wiped away with a large eruption. However, just as the times of increased activity don’t suggest that the Earth is “out of control” or “heading to heightened eruptions and earthquakes” due to any number of unfounded reasons, this period of relative volcanic and seismic quiescence doesn’t mean that the Earth is doing anything different that business as usual. (And as noted on Twitter, it also doesn’t mean this is the “quiet before the storm”.)

** Note: One might argue that submarine eruptions could go unnoticed. However, a VEI 4+ would leave telltale signs as well, including pumice rafts, strong seismicity and changes in ocean temperature (locally). As an example, the very small eruption from El Hierro in 2011-12, albeit in shallower water, was easily seen from space.

P.S. 2012 has been a very active year for our closest star, the Sun. Now, I won’t go too far, but why has the Earth been so quiet tectonically when the Sun has been so active? I’ll leave that to the folks who think the Sun somehow plays the dominant role in earthquakes and eruptions.

from:    http://www.wired.com/wiredscience/2012/08/2012-a-volcanically-quiet-year-so-far/#more-123108