Is it possible to find the magma chambers that produce supervolcanos? 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?
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.