This research is to use tomographic imaging techniques to determine the subsurface structure beneath Mt. St. Helens at a very high resolution (on the order of 100 meters). By the use of 5000 previously unused earthquakes, a three dimensional velocity model will be determined which can then be used to improve the spatial resolution of earthquake locations. Gravity, aeromagnetic and attenuation data will be used to constrain the structural solution. A goal of the work will be to distinguish between conflicting models of the plumbing system for the transport of magma to the surface. Because this work has the potential for increasing the understanding of the interaction of magma transport and seismicity for the major Cascade range strato-volcanos, it has application to the National Earthquake Hazard Reduction Program.
