When Iceland’s Katla volcano erupts next, could it be 100 times as powerful as the recent Eyjafjallajokull eruption?
Maybe, yes. Hopefully not. Probably not, but, let me explain…
The current thinking and assumption is that Katla will possibly be as powerful as ten times that of the recent eruption of Eyjafjallajokull, which is a reasonable expectation given the fact that the 1918 Katla eruption was indeed almost ten times as powerful as Eyjafjallajokull.
Volcano explosiveness is ranked on a scale from 0 to 8 (Volcanic Explosivity Index – VEI), and each increase in number represents a ten times increase in explosiveness (logarithmic scale). The total volume of ejected material also known as ‘tephra‘ (the fragmental material, regardless of size, produced by volcanic eruption), as well as plume height are the most important criteria factored in to VEI.
The recent Eyjafjallajokull volcano eruption in Iceland was ranked on the low end of VEI 4 and released about 140 Million cubic meters of material , of which about 80 Million cubic meters went into the atmosphere by way of the ash plume. It affected aviation in the region for weeks, translating to global transportation issues of both human and cargo, and had a measurable negative economic impact.
Imagining the impact of a Katla eruption on a scale of ten times worse than Eyjafjallajokull is bad enough, but when considering an impact of one hundred times worse, one begins to cringe…
VEI 4 (ejects .1 – 1 Billion cubic meters of tephra, plume height 10 – 25 km)
VEI 5 (ejects 1 – 10 Billion cubic meters of tephra, plume height >25 km)
VEI 6 (ejects 10 – 100 Billion cubic meters of tephra, plume height >25 km)
The 1918 Katla eruption has been ranked VEI 4+ and VEI 5, ejected 700 Million cubic meters of material, was about ten times the explosive power as Eyjafjallajokull, and nearly comparable with the 1980 eruption of Mount St. Helens.
The fact is, the magma chamber beneath Katla is large enough to produce a VEI 6 eruption. The chamber has a volume of about 10 Billion cubic meters and the caldera has an area of about 42 square miles (108 square kilometers). The total volume within the magma chamber, if completely filled and ejected, could touch the bottom range of a VEI 6.
When Katla erupted in 934 AD, it produced one of the world’s largest known lava flows which amounted to 18 Billion cubic meters while also ejecting 5 Billion cubic meters of tephra. This put it solidly within VEI 5 and would certainly have been VEI 6 if some of the enormous amount of lava had ejected as tephra instead.
History often repeats itself
Whether Katla goes off as a VEI 4+, 5, or 6, it will have a significant impact on today’s world. Regardless of the scale, air travel will be severely impacted, particularly in Europe, which will ripple down through the economies of the world. Localities in the path of the ash plume will likely endure regional crop and livestock failure from ash fallout, as well as the threat of poisoning from inhalation.
History favors a probable VEI 4+, maybe VEI 5 type of event, however a VEI 6 worst case scenario will bring significant devastation in that it will be much wider spread. It will surely have a global impact as temperatures could drop enough to cause wide spread crop failures while our weather is effected from such a large volume of ash ejected into the stratosphere. Having said that, even a VEI 5 could also cause a world wide temperature drop depending on which end of the VEI ‘5’ scale.
Katla historically erupts following the eruption of Eyjafjallajokull (which erupted 14-April and went on for 10 days). Katla’s volcanic eruptions have ranged in duration from 13 days to as long as 120 days, while the last three Katla eruptions have been between 20 and 28 days.
We will not know the answer to the question of 10x or 100x until it happens, but in the mean time, if I lived nearby, I would stock up with some extra food and water just in case the disruption is bad enough. We all know that it will happen, it could be tomorrow or months from now, but the clock is definitely ticking.
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