Supervolcanos have occurred in the recent geological past, but not within the past 74,000 years. Is it possible to find the magma chambers with no previous history of supervolcanic activity that are likely to produce supervolcanos?
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2$\begingroup$ I'm afraid I'm not clear on what information you're after - whether we can image magma chambers currently underlying known supervolcanoes (and if so what information we can get e.g. are the contents solid, mushy or liquid; can we tell anything about injection rates; etc) versus identifying potential supervolcanoes with no current surface expression. If you can flesh out your request a bit, I'll happily respond :-) (PS it'd be nice if you added at least a brief textual image caption/description for accessibility purposes.) $\endgroup$– kaberettCommented May 5, 2014 at 18:12
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1$\begingroup$ @blunders By "future super-eruption sites", do you mean locations with no previous history of supervolcanic activity? Or predictive abilities with respect to known supervolcanoes? (Also, it'd be great if you could edit the clarifications into the main question For The Future when comments will vanish :-) $\endgroup$– kaberettCommented May 6, 2014 at 0:50
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2 Answers
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I am a seismologist, not a volcanologist, but we can use a method called seismic tomography to understand the size of magma chambers.
This method is similar to a medical CT scan - the magma mush will have a slower seismic wavespeed than the surrounding 'normal' rock. Therefore, we can use this to determine the size of magma chambers from a tomographic image.
Even if a volcano does not appear to be active at the surface, it could still overlie a magmatic anomaly.
This approach was recently used to estimate the seismic of the Yellowstone magmatic body. See this paper: http://onlinelibrary.wiley.com/doi/10.1002/2014GL059588/abstract
Seismic tomography can theoretically be applied to any region, but we just need to have enough seismic sources nearby (e.g. earthquakes) to be able to do this accurately.
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Complementing the answer by @seismo_steve, two other geophysical ways of detecting magma chambers are through their density and conductivity anomalies.
Seismic tomography is able to detect the chambers because they cause an anomaly in the propagation velocity of seismic waves. Likewise, the chambers cause an anomaly in the gravity field because their density is different from the surrounding/reference value. Geophysicists can use this gravity anomaly to estimate the size and shape of the magma chamber (see this paper by Chaves and Ussami, 2013, for an example also in Yellowstone).
Long-wavelength electromagnetic methods, like magnetotellurics, might also be able to detect the electrical conductivity anomaly associated with the magma chamber (though there are some restrictions). See this classic paper by Newman et al. (1985).
