9 comments on “Continuing eruptions at Volcan de Fuego, Guatemala

  1. Nasty system indeed, thanks for the article! This is one of the few (active) volcanoes I have seen up “close”, though it was idle the week we were in Antigua way back when. Pardon my ignorance, but fo most stratovolcanoes suffer gravitational flank collapses eventually? Does the type of magma it erupts affect this (i.e. its layers)?


    • My feeling, as a total amateur, is that pretty well any stratovolcano with activity concentrated at a single central vent will become a serious candidate for slope failure once it gets to an edifice height/prominence over 3000m, simply from structural instability -upper flanks are oversteepened. Plus the additional factors of tectonic earthquakes and the likelihood of hydrothermal alteration internally. The topography of the volcano’s ‘basement’ is another factor; growth on an escarpment will make the structure unstable at an earlier stage than for one growing on a level substrate, and will influence the direction of flank collapses: for the Fuego complex west or SW, for Sangay (for example) eastward, for Aleutian volcanoes predominanly north, and so on.

      Does this sound reasonable?


      • Great question, Tom. Michael has pretty much captured it.

        I would approach the discussion from another direction. Most stratovolcanoes are built of relatively soft stuff – tephra layers, some lava, welded tuff from pyroclastic flows.

        Here in the north, we have more experience with snow avalanches than we would like, particularly late in the season when we get varying layers of snow. It is the difference in the composition of the layers that allow the overall mass of whatever is on top to break the tensile strength of the top layer(s), the internal friction holding it in place and start the slide of snowpack downhill. The weaker layers end up working like greased skids for the higher, more structural layers. This is why you initially see blocks of snow in the early stages of snow slides.

        I look at the relatively soft material of stratovolcanoes much the same way. There is not a lot of tensile strength in the stuff and it is layered with material with no tensile strength at all (tephra fall for example). Additionally, sometimes the actions of the volcano assist the collapse like we saw with St. Helens. Earthquakes also help destabilize a stratovolcano cone.

        Finally, even well welded structures with lots of lava flows suffer flank collapses. Think the Hawaiian islands, which are surrounded with debris of flank collapses. Of course, all are higher than 3,000 m above the ocean floor. Cheers –


  2. Howdy all –

    USGS created a you tube video of the motion of one of the buildings here in Anchorage during our 7.1 Richter quake a couple months ago. It is 17 stories high. Side to side motion is magnified. Time is real. I regularly do business in the building and have wondered from time to time how it would perform in a large quake. Now I know. There was no damage to the building. As the quake took place on a Saturday night, it was mostly empty so nobody that I know of got to ride it out at the top. Cheers –


    • Wow, it really shook through till long after the quake ended. And quite evenly in all directions, well built! Interesting that the amplitude increased to nearly full for a second time after 1:20, when there were no particularly high spikes in the wave form.


  3. Howdy all – Interesting paper out about thinning of Greenland icecap is caused by thinning crust that was in turn thinned a bit by its passage over the Icelandic hot spot. The thinned crust allows more heat to make its way to the surface which in turn warms up the underside of the icecap and allows the glaciers to move faster. Western Antarctica has a similar volcanically warmed ice cap. Some believe the Icelandic hot spot was responsible for the SIberian Traps. Cheers –



  4. Pingback: Continuing eruptions at Santiaguito, Guatemala | VOLCANO HOTSPOT

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