New Evidence of the Causative Relationship between Well Injection and Microseismicity in the Geysers Geothermal Field

Basic Information
Author: Greensfelder, R.W.
Description:A new analysis demonstrates a rough correlation between microseismicity with focal depths greater than or equal to 2 km and injection in one well located in the southeastern portion of the Geysers geothermal field (in and near Unit 13), confirming what Stark (1990) has shown for the area to the northwest. The abrupt onset of microseismicity near well McKinley-5 early in 1980 follows the initiation of injection there by about three months. Until 1986, injection and numbers of earthquakes within 3000 feet of this well appear to be roughly correlated, with injection increases or decreases leading the rise or fall of microearthquake numbers. For the years after 1986, there seems to be no correlation between earthquake frequency and injection; this may be due to the overall decline of injection volumes in the well. A similar analysis was conducted for well Thorne-7, but no correlation is evident. However, after the start-up of injection in 1984, microseismicity near this well did become more continuous from month to month.
Publication Date:
Author Contact Information
Distributor Contact Information
Organization Name: Arizona Geological Survey
Street: 416 W. Congress St., Suite 100
City: Tucson
State: AZ
Zip: 85701
Phone: 520-770-3500
Geographic Extent
North Bounding Latitude: 38.9670267701
South Bounding Latitude: 38.4526576501
East Bounding Longitude: -122.594035022
West Bounding Longitude: -123.396036975