A study of the geothermal resources of Imperial Valley of Southern California was initiated by a group of researchers at the University of California, Riverside. The aims of the study program are twofold: (1) to map the areas of abnormal heat flow which may become potential geothermal-energy exploration targets, and (2) to study the fundamental geologic and geophysical factors affecting the abnormal heat-flow regime in the valley.

In the first phase of the Imperial Valley project, shallow-hole temperature gradients of up to 0.78°C per meter were measured; the mean for all readings was 0.184°C per meter. These values are more than one order of magnitude greater than the average value for the entire earth, suggesting that vast amounts of geothermal energy are to be found in the valley at a relatively shallow depth. At least some of the geothermal highs correspond to the gravity highs in the valley, indicating that convective heat flow must have caused densification of the sediments.

Deep electrical-resistivity exploration was useful in confirming the shallow-hole geothermal measurements and in identifying areas of high heat flow. Electrical resistivity proved very useful also in mapping an uncharted system of faults (named "the West San Andreas" system) running through Imperial Valley.

From the preliminary findings it is concluded that the Imperial Valley can be classed as a significant source for geothermal energy in California.

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