The goal of this project was to provide constraints on the subsurface geometry of the vent, feeder conduit(s), and possible intrusive bodies in the Novarupta Basin, Valley of Ten Thousand Smokes (VTTS), Katmai National Park, Alaska. This research was designed to support the Katmai Drilling Project, a consortium involving the DOE, NSF, other government agencies, and several universities. Our work aimed at providing information to help guide site selection and identify targets for the drilling program. However, our research also has contributed to the understanding of silicic volcanic systems in general. Understanding the subsurface geometry of the vent is essential for accurately modeling the present thermal regime in the vent region and the eruption dynamics. Determining the origin of surficial fractures indicated the effect of compaction and consolidation of tephra and orientation of the depositional surface on fracture formation. Our research plan included (1) completion of a detailed topographic-structural map of surface fractures including spatial distribution and relative displacements; (2) numerical modeling studies that related surface fractures to major subsurface structures; and (3) interpretation of the origin of surface fractures in light of these model studies.