Theoretically, I ponder what type and strength a supereruption would generate, say for example at the Yellowstone caldera? The last supereruption was roughly 70,000 years ago when Toba erupted. It's claimed that this single event bottlenecked our species and nearly ended us? My curiosity is more towards the effects in the immediate vicinity of the collapse, in particular the seismic effects and their severity? Large quakes and tsunamis if near ocean?

  • $\begingroup$ While not strictly an answer to your question, there was a fairly large volcanic eruption at yellowstone about 170,000 years ago and the eruption 1.3 million years ago was comparatively smaller than the big one, 2.1 million years ago and the 2nd biggest one 640,000 years ago. The point is the super-volcano "clockwork" isn't nearly so neat and predictable as is often suggested. Smaller eruptions happen every 100,000 years or so, but a "big one" isn't necessarily "due". Source, Wiki, USGS, not difficult to google. $\endgroup$ – userLTK Jan 25 '16 at 5:07

Volcanic earthquakes aren't actually all that strong. That's quite easily understandable by just looking at length scales: In the largest earthquakes that happen on earth, tens of kilometers of subduction zones rupture at once, releasing the stress that has built up from two plates moving past each other (but being locked) for decades.

Even large calderas cannot produce faults of this length that are sufficiently long and linear and can rupture in the same quake. Consequently, earthquakes in volcanic zones are usually much smaller than the largest ones we experience on earth.

The global effects of supereruptions are not due to earthquakes or tsunamis, but due to the gases, ash and sulphur that ends up in the atmosphere and that leads to global cooling for several years.

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