Supposedly Hekla in iceland is supposed to dwarf Mt St Hellens, vesuvius and the 2010 Eyjafjallajökull eruption.

Loki if it erupts is said that it could kill hundreds of thousands due to it toxic sulfer clouds that would cover the northern hemisphere (seeing that killed over 100,000 the last time it erupted in the late 1700s).

And Katla is supposed to be the worst of them all that would put out a ashen cloud much worse then Pinatuba ( which lasted 12 days, where katla's worst eruption spewed ash for over a year due to the size of its magma chamber) and put out a sulfer cloud much worse then loki in 1783. Supposedly it would put enough pollutants into the air to cool the global temperature by 2 degrees Celsius. Also say goodbye to air travel with that kind of ask in the atmosphere.

I'm more worried about the Jackson Hole Caldera if such things are to be worried about.

the real big is eruption of sun spots.  happened back in mid-1800s and blew out all the telegraph for a long time.  what do ya think it would do today, worldwide?  its due.

I spent a few weeks over in Iceland with the eruption in 2010 and a week or so with the eruption in 2011. Katla will change the way the world works although I don't think it will be the SHTF event that people usually think of. It will do serious damage to Europe since that's the way the wind almost always blows from there, in fact it will hit crops and other things requiring lots of sunshine but won't directly affect day-to-day for a little while. The long term effects might be issues with crops and airplanes might have to be re-engineered to be able to deal with the ash but it could just shut down for 6 months or so. The temp drop might be obnoxious but since we have been warming a bit for the last few decades it would actually help things and might reverse the weather events that keep getting worse. I have been around a lot of disasters due to my line of work and I find that SHTF events are pretty localized. Things like Katrina, Sandy, Joplin, or massive flooding are far more likely and being prepared for something like that is imperative for those people who want to make sure they aren't stuck in the stampedes of sheeple who will freak the fuck out when it happens.

It's going to be a great show though, I hope to be there

Katla (myjarfaraskoll(sp?), can be tracked on Iceland site, en.vedur, google seismic activity Iceland volcanos.       In past 2000 years, Katla has erupted 18-30 months after little sister, each and every time, plus a few times without the warning.  Has averaged 20x larger than the 2010 12day eruption.

1918 the last eruption: Here in Maine, menfolk went out to cut wood for winter on 6" of ice on the lakes the day after Thanksgiving (my family recalls)

Ice that year in the bays froze clear out to the islands (sea ice).

Figure 1-2 climate zones colder for 1-2 seasons, cutting out significant % of N. hemispher northern most grain belt, depending on the time and extent of the eruption.

Grain and meat prices will be VERY adversely affected.  Seed corn will last 10 years well stored, much longer long term stored.  Roy's Calais flint was the only corn that survived in New England 1816, when a major volcano blew (Java?)    Other good corns include OP painted Mountain, and similar.  I have kucyk, but seed supply is out for this year.