Micro-Earthquake At Coso Geothermal Area (1993-1994)

GEOTHERMAL ENERGY

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Exploration Activity: Micro-Earthquake At Coso Geothermal Area (1993-1994)

Exploration Activity Details
Location	Coso Geothermal Area
Exploration Technique	Micro-Earthquake
Activity Date	1993 - 1994
Usefulness	useful
DOE-funding	Unknown

Exploration Basis

Multiplet analysis

Notes

Instances of microseismicity in seismic doublets which are co-located hypocenters that appear to have nearly identical waveforms were searched for. Using 1085 high-quality events from 1993 to 1994, they identified numerous doublets, some occurring within minutes of each other. The hypocentral data was subdivided into spatial clusters to reduce the computational burden and evaluated multiple cross-correlation pairs, assigning scores to each pair. The multiplets do not appear to be true repeating events; rather, they are clusters of small, nearly identically oriented ruptures, perhaps representing swarms of fractures activated by fluid-pressure fluctuations. Using the small volumes encompassing each multiplet, the fracture densities are estimated to measure between 0.02 and 0.4 m⁻¹ and are largest near the injection wells.

References

• Feng, Q.; Lees, J.M.   (15 April 1998) Microseismicity, stress, and fracture in the Coso geothermal field, California