Question: Is there any way to predict when Yellowstone volcanoe will erupt, and if it does what will happen?

David Pyle answered on 16 Mar 2011:

Yellowstone is now a very well monitored volcano, but we have never seen a volcano like this erupt (in recent history). The real challenge with forecasting the next eruption (and it will erupt) is getting the forecast right – it’s likely that there could be many years of unrest before even the next small eruption. Until we know how the system works once it’s live, there are quite likely to be false alarms – not necessarily from the scientists, but from the press.. You only have to look on the internet to see a prominent Professor of String Theory pronouncing (somewhat wrongly) on the current activity!

If it does erupt – then the worst case will be a repeat of the event 640,000 years ago: this dropped ash across 2/3 of the continental US and Canada. This would disrupt power supplies, communications, water supplies and agriculture. It would modify, slightly, the weather of the US for a few decades (until the ash was washed away, or vegetated). We have a pretty good idea about how this scenario might unfold – but there will be enough warning of such an event that some protective steps for survival could be taken. There is a very low chance of anything of this scale in the near future. Much more likely is a very small eruption, perhaps with a lot of steam explosions and a bit of ash – and quite a lot of mass hysteria. This could be very difficult to manage!