Abstract

Ground-based transient electromagnetic (TEM) data were acquired by the U.S. Geological Survey (USGS) at 16 locations of California’s southwestern San Joaquin Valley and Central Coast regions to define the electrical resistivity structure of hydrogeologic materials. Data were acquired using the ABEM WalkTEM system (Guideline Geo Ab, Sundbyberg, Sweden). TEM data were processed and numerically inverted to derive one-dimensional resistivity structure using SPIA (Aarhus Geosoftware, Aarhus, Denmark). The resulting models reveal vertical variations in electrical resistivity associated with geologic structure and zones of high salinity groundwater.