Geophysical Investigations near Yuma, Arizona

Abstract

VLF (Very Low Frequency), magnetic, TEM (Transient ElectroMagnetics), and Seismic were performed in Yuma, Arizona over two weekends in February and March of 2005. The targets of interest in Yuma included the depth to the shallow bedrock, the trace of the Algodones Fault, and the distribution and thickness of clay units. The VLF and magnetic surveys both proved not to be valuable for the interpretation of groundwater or bedrock depth. The Seismic surveys found a quartz monzonite horst structure at a depth of 8 meters and 250 in length and a graben at 8 meters depth and 48 meters in length. The TEM surveys were performed along Line 2 and Line 4 for Site One, Line 1 and Line 3 for Site Two, and SG1 line and SG2 line for Site Three. The TEM survey, located near the Seismic surveys, was in agreement with the findings of these Seismic surveys. At all sites, the TEM surveys were useful for determining depth to water table. At one site, the TEM survey mapped substantial near-surface clay layers.