This keeps coming up, and I keep getting tagged, so here are some comments: cbc.ca/news/world/iceland-volcano-area-north-of-bardarbunga-evacuated-1.2741422 Yes, it will probably erupt. Eventually. Grimsvotn/Lakagigar has had large historic eruptions including one in 1783. See volcano.si.edu/volcano.cfm?vn=373010 . Yet the claim (originating on DailyKos) that the 1783 eruption triggered a winter that killed millions is unverifiable and at best exaggerated. Its also not a supervolcano. So, unlikely to trigger nuclear winter, but nonetheless significant. Large eruptions generally have seismic precursors. Thats normal. Often, earthquake activity picks up months before the eruption. This weeks Smithsonian GVP report gave the start of heightened seismicity as 13 Aug, so I wouldnt expect a huge blast immediately. St. Helens is a good example of this. My memory of the papers is somewhat dim (Id have to dig through many reprints), but Mt. St. Helens experienced comparable seismic activity early in the 1980 eruptive cycle. To sketch a rough timescale here (mostly from Steves stories, 12+ years ago), earthquakes started mid-March 1980 and the first small summit explosion came 24-25 March. The lateral blast was 18 May. By the time of the blast the PNSN was recording daily M = 4.0-4.5+ events, with volcanic tremor strong enough to saturate stations 100 km away. Bardarbunga isnt there yet. As another example, Mt. Pinatubo experienced elevated seismicity starting months before the big eruption (June 1991). I know this one firsthand: my first research job was relocating the seismicity. Neither St. Helens nor Pinatubo triggered a nuclear winter. Pinatubo lowered global temperatures around half a degree temporarily. St. Helens didnt. But they certainly caused regional havoc. Bear it mind, it doesnt take a *big* eruption to hamstring air travel -- especially in Iceland, where ash disperses into all the common trans-Atlantic flight paths. As they say, expect delays.
Posted on: Wed, 20 Aug 2014 23:52:48 +0000
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