Seismic Tomography of Concrete Structures Phase 1: Equipment Test

This report contains the results of Phase I of the seismic tomography research project currently being performed by the Seismotectonics and Geophysics Group, with funding from the Dam Safety Office. The ultimate goal of this research project is to develop Reclamation’s capabilities for efficiently acquiring high-quality seismic tomography data on concrete structures for the purpose of imaging variations in concrete quality within the structure. As part of this project, the usefulness of the seismic tomography method as applied to concrete structures will be evaluated by acquiring and processing seismic data from one of Reclamation’s concrete dams. The project is divided into 4 major phases: gathering background information from other researchers and testing various types of equipment (Phase I); preparing for the field test by purchasing and constructing equipment, modifying data processing software, and performing forward modeling (Phase II); data acquisition and preliminary on-site data processing (Phase III); and final data analysis and report preparation (Phase IV). The primary purpose of Phase I of this research project is to determine the types of sources, receivers, and coupling methods that are likely to produce the highest quality seismic data on concrete structures. Other important factors that are considered when evaluating various field equipment are equipment costs and difficulty of installation. A secondary purpose of Phase I is to determine the frequencies of the seismic signals that are likely to be acquired through concrete dams over the distances and angles necessary for application of the seismic tomography method.