The main focus of this dissertation is development of innovative approaches to the high resolution imaging of the earth that take advantage of recent advances in seismic instrumentation (dense arrays) which facilitate the unaliased recording of local earthquakes. These new methods can be applied to the study of any structures at depth as long as there is an adequate distribution of local seismic energy available for effective illumination. Introduction places the research reported in this dissertation in the context of the broader field of seismic imaging. Chapter 1 investigates geometries favorable to body wave imaging by interferometric analysis of distributed but known subsurface sources, with application to the aftershock sequence of the 2011 Mw 5.8 Virginia earthquake. Chapter 2 and Chapter 3 use microseismicity recordings at the geothermal field at Krafla, Iceland, to image magmatic features at depth using two distinct approaches: seismic interferometry and reverse Vertical Seismic Profiling (rVSP). Strong reflections from a body at the same depth as magma encountered in boreholes at Krafla, Iceland were detected and mapped by both techniques. Deeper reflectors suggest a distributed system of smaller magma sills rather than a large pervasively molten feeder chamber at Krafla. Chapter 4 reports an effort to use subduction zone earthquakes in central Alaska to produce a high resolution image of the subducting oceanic lithosphere. The results include one of the first seismic images using an interferometric method with local earthquakes to successfully image mantle structure with a greater resolution than that previously achieved with more conventional methods. Chapter 5 of this dissertation presents the first industry scale 3D reflection image of deep intrabasement features in the United States, generated by opportunistic processing of pre-existing oil exploration data. More importantly, this work illustrates how modern, nodal industry seismic reflection surveys are routinely collecting 3D imagery that- if preserved and properly processed- can yield important new insights into the structure and evolution of the deeper parts of the earth.