Its had three huge blows over the past couple million years, but numerous smaller ones. Lots of talk about what another huge one could do. But I’ve never seen a description of what the far more likely little one would do. That we should know and probably can plan for.
That’s a very, very good point.
What would be the effect(s) of, and how should we plan for, a much more likely Mt. St. Helens, Pinatubo, Krakatoa, or Tambora (as we go down the probability scale but up the intensity scale) size event?
Two interesting side notes:
The usually quoted Volcano Emissivity Index (VEI) is a cumulative figure, over the duration of an eruption. So, Tambora has a VEI of 7, and Krakatoa a VEI of 6, even though Krakatoa had a substantially greater peak explosion: It propelled ash 50 miles into the atmosphere, and is believed to be the loudest sound heard in recorded history. Krakatoa also shot an unusually large amount of SO2 into the stratosphere, causing greater weather and climatic effects than a VEI of 6 might suggest.
2nd, while most volcanoes and faults misbehave in moderate fashion (if something like a Krakatoa can be called “moderate”!) much more frequently than the occurrence of extreme events, I am not sure all can be expected to behave this way over “short” periods of time, say, 10,000 years or so. I am also quite unsure that the smaller events are distributed at all evenly. Maybe they “bunch up” around cataclysmic events? This worries me a bit, in the case of the New Madrid fault. Why?
Historically, the “big ones”, or perhaps more accurately, series of “big ones” occur on the New Madrid fault system every several hundred years, or so. But we don’t know if more moderate events, say, an order of magnitude less, happen with any frequency between the major events, or if they occur mainly as pre-shocks and aftershocks bunched around the main events. There also seems to have been not much in the way of pre-shocks in advance of the first main shock on 12/16/1811 — a not unusual pattern, for earthquakes. There are many small quakes, but there is also little apparent movement of the fault. What all this means is unclear. Is little energy being dissipated now, and, would a future big quake / series of big quakes again happen with no warning, despite improvements in our understanding of quakes in general?