But yes, the recent quake in Japan physically altered the tilt of the earth's axis, so we're clearly all doomed. And I saw Jesus's face in my toast this morning. The beardy bastard!
When Mount Tambora (Indonesia) went up in 1815, it caused (to all intents & purposes) a 'Nuclear Winter.
Crops failed, due to the lowering of the mean temperature, & lowered sunlight levels
There was a 'Potato Famine' in Ireland, 'Frost-Fairs' took place on the River Thames
And mean temperatures only dropped by a couple of degrees!!
Having said that, the cataclysmic event that really scares me is, if 'Yellowstone' goes 'bang', if it does, we're basically all knackered!!
(the other one is a large Meteorite strike into the Atlantic Ocean, that'd make Japans Tsunami look like the ripples in a bath)
If you saw the 'Supervolcano' 'drama-mentory', you'll know what I'm on about... as they stated in the opening title-sequence
'What you see here is a true story, it just hasn't happened..... YET'
http://www.bbc.co.uk/sn/tvradio/programmes/supervolcano/index.shtml
http://en.wikipedia.org/wiki/Yellowstone_Caldera