Mount Pinatubo had a Volcanic Explosicity Index of 6. 200 years ago there was an eruption with a volcanic explosivity index of 7, at Mount Tambora:

Tambora erupted in 1815 with a rating of seven on the Volcanic Explosivity Index; the largest eruption since the Lake Taupo eruption in AD 181. The explosion was heard on Sumatra island (more than 2,000 km or 1,200 mi away). Heavy volcanic ash falls were observed as far away as Borneo, Sulawesi, Java and Maluku islands. The death toll was at least 71,000 people, of which 11,000-12,000 were killed directly by the eruption; most authors estimated 92,000 people were killed but this figure is based on an overestimated calculation. The eruption created global climate anomalies; 1816 became known as the Year Without a Summer because of the effect on North American and European weather. Agricultural crops failed and livestock died in much of the Northern Hemisphere, resulting in the worst famine of the 19th century.

The Year Without a Summer, also known as the Poverty Year or Eighteen hundred and froze to death, was 1816, in which severe summer climate abnormalities destroyed crops in Northern Europe, the American Northeast and eastern Canada[1][2]. Historian John D. Post has called this "the last great subsistence crisis in the Western world."

If you have solar (all it needs is maintenance), why bother with nuclear.  The long winter scenario is a reason for maintaining nuclear development, but my thought is that nuclear power stations demand certain things from society that solar power stations don't, so I'd rather see nuclear as part of a long-term "worst case" development plan (linked to trans-national university research depts.--something like that) rather than a day-to-day (nation state) working policy.

Maybe I mean that solar is scaleable and, linked to wind and wave tech., can produce energy from the one-person unit up, whereas nuclear needs a state to start with...or sommat!

I went at a tangent to super volcanoes because I was recently reading about the toba catstrophe theory, which suggests that we are all related to the 10,000 humans who survived, and 75,000 years...is a long time ago, but not all that long...

...was my point.  Sorry if I came across negatively!

Don't fight forces, use them R. Buckminster Fuller.

Coz something big will probably happen in the next 100,000 years or so.

I don't find the "underground living" idea inherently sinister.  It could just as likely be "spaceship earth" but where we've built human-satisfying living environments (I know, unlikely!)...a sort of state of the art "arc" project.

Also, I don't imagine that we'd re-enter to a mars-scape; I'd expect plenty of plants to survive.  It's more a case of making sure that the plants we eat are--the seeds are--available for when the sun's back.

"grublike"--all covered in dirt!

I'm imagining underground gardens!

Don't fight forces, use them R. Buckminster Fuller.

Interesting quake by quake info from Yellowstone here:

http://volcanoes.usgs.gov/yvo/

http://volcanoes.usgs.gov/yvo/2006/uplift.html

Imagine the tech needed to calm a supervolcano!  Huge shafts to release the pressure?  Sinks to pour the magma down?

Don't fight forces, use them R. Buckminster Fuller.