|Schlumberger DC resistivity soundings were made in the Long Beach-Wilmington
area of Los Angeles County, California to map subsurface resistivity structure
and to correlate areas of low resistivity with saltwater intrusion. A total
of 78 soundings were made in a highly developed, urban area, making the
selection of measurement sites challenging. Soundings were interpreted
using automatic interpretation procedures to produce resistivity-depth
functions. Cross sections were constructed from the layered-earth interpretations.
The results are also displayed as resistivity depth slices. Resistivities
of less than 4.5 ohm-m are interpreted as being caused by intrusion of
seawater into pore spaces. The extent of this zone roughly parallels the
coast. However, the tidal flow in the Dominguez Channel has a low resistivity
zone associated with it that extends at least 3 kilometers further inland
than in surrounding areas.