Karst environments are characterized by voids, i.e. sinkholes and conduits of varying size that arise from the active
dissolution of carbonate rock by acidic groundwater. These voids, whether air-, water-, or soil-filled, can be difficult
to image using near-surface geophysical methods due to the limited investigation depths of most active-source methods. In
addition, due to the significant effort it takes to collect active-source data, investigators are often unable to monitor
spatio-temporal variations in the subsurface. The ability to detect, image, and monitor subsurface voids improves the
understanding of processes that create and transform voids, a vitally important insight across a variety of scientifc
disciplines and engineering applications, including hydrogeology, geotechnical engineering, planetary science and even
issues of national security. Using a 54-element nodal array (1C and 3C sensors), I image the subsurface of the USF GeoPark
with ambient noise surface wave tomography. I also use complementary active-source geophysical datasets (e.g. 2D ERT)
collected at the GeoPark to constrain and/or validate the tomography results. I address two research questions with
this study: (1) How do ambient seismic methods complement active-source near-surface methods? (2) Can ambient noise
tomography resolve voids in the karst environment? In this thesis, I discuss my answers to these questions and present
the current state of surface wave methods in the karst environment, including the feasibility for utilizing ambient
noise methods to monitor spatio-temporal changes in sinkhole and conduit formation. In addition to the ability to use
seismic methods for temporal monitoring, ambient noise provides lower frequencies than what are achievable with active-source
seismic methods. Using frequencies from 5-28 Hz, ambient noise tomography is able to image deeper into the subsurface (up to
100 m at 5 Hz) than previous active-source seismic studies at the GeoPark field site. This study yields a more robust and
simple method to image voids in covered karst environments and a long-term installation of ambient seismic nodes enables
future investigations of spatio-temporal variations in void structures.
Crustal and uppermost mantle S-wave velocity structure beneath the Japanese islands from seismic ambient noise tomography
