Telluric mapping over the Mesa Geothermal Anomaly, Imperial Valley, California
The telluric prospecting method employs naturally occurring ac electric fields in the earth to measure the variations in lateral electrical conductance within a sedimentary basin. It is a relatively inexpensive, rapid and deeply penetrating method of estimating electrical conductivity. Telluric measurements were made at thirty-nine stations in the vicinity of the Mesa Geothermal Anomaly, Imperial Valley, California in order to evaluate the usefulness of the method as a geothermal prospecting tool. The area of investigation is characterized by thick (about 3 km) and highly conductive (resistivity on the order of 5 ohm-m) sediments. The large sediment depth and conductivity necessitated a more sensitive (p-p noise level = uV) apparatus operating at lower frequencies (.0067 hz) than is normally employed for telluric investigations. Relative ellipse areas were determined for the stations and plotted as total field and residual contour maps. These maps clearly reveal the presence of the thermal anomaly. They coincide well in geometry with the anomaly shown by shallow thermal gradient data and are consistent with temperature data from five deep wells in the area.
- Research Organization:
- California Univ., Riverside (USA). Inst. of Geophysics and Planetary Physics
- OSTI ID:
- 7102385
- Report Number(s):
- PB-262828; IGPP-UCR-75-10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
150301* -- Geothermal Exploration & Exploration Technology-- Geophysical Techniques & Surveys
58 GEOSCIENCES
580203 -- Geophysics-- Geophysical Survey Methods-- (1980-1989)
CALIFORNIA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRICAL SURVEYS
EXPLORATION
GEOPHYSICAL SURVEYS
GEOTHERMAL EXPLORATION
GEOTHERMAL FIELDS
GEOTHERMAL GRADIENTS
IMPERIAL VALLEY
MAPS
NORTH AMERICA
PHYSICAL PROPERTIES
TELLURIC SURVEYS
TEMPERATURE GRADIENTS
USA
WESTERN REGION