I think that with caldera collapses they are pretty short term events, though the impact can last for yours. There does seem to be a connection between 'trap' events and serious extinctions. For example the Siberian Trap seems to be in the right place and time to have contributed to the great dying some 250 million years ago
caldera collapse-short term events the following damage being caused by global cooling, emissions responsible for cooling rain out very quickly vs the Trap events-sustained eruptions with initial cooling which followed by a CO2 buildup and long term warming, the accumulated CO2 being very slow to dissipate out of the atmosphere..
Or how much volcanic particulates can filter the sun? And I wonder how fragile the world economy is; if California was 100% destroyed what effect would this have on the rest of the world? Even a major natural disaster rendering Los Angeles out of commission for a few years would bring the US economy to it's knees. And how is extinction defined; 100% or 75% or 50% or ??
Which is why I say geologically humans are just along for the ride. What's interesting today, with our new knowledge, is humans continue to bet against the odds of a catastrophic natural disaster ever happening; we live on volcanoes, on earthquake fault lines, at or below sea level, on vertical eroding cliffs, etc. etc. etc. We are guaranteeing that when we do experience the 'big ones' we will feel the maximum pain...but government will be there to soften the landing...
losing california would be devastating to the US economy which in turn have a domino effect on other economies...
The economy of California ranks 12th largest in the entire world...for everyone who hates CA so much they better hope things go okay...because as CA goes so does the USA and the world. Pretty amazing all the horrific potential we have in CA for catastrophe...
And apparently we have 20 volcanoes! http://www.volcanodiscovery.com/california.html But in CA we never worry about volcanic eruption or earthquakes or tsunamis, etc...our main worry is bacteria infected tofu or bean sprouts...