My students and I have been working with researchers from the University of Maryland and NASA to image the subsurface in the vicinity of SP crater, located north of Flagstaff in the San Francisco Volcanic Field. This field season we have been using magnetometers, broadband seismometers, NodalSeismic nodes, differential GPS, and a Propelled Energy Generator (PEG) to locate subsurface fractures that are hypothesized to serve as magma conduits for volcanic eruption in the field. Many thanks to PASSCAL  for the use of the PEG.