Open AccessFractal clustering of induced seismicity in The Geysers geothermal area, California
Author(s) -
Henderson J. R.,
Barton D. J.,
Foulger G. R.
Publication year - 1999
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1046/j.1365-246x.1999.00939.x
Subject(s) - induced seismicity , geothermal gradient , geology , seismology , fractal dimension , fractal , geophysics , mathematical analysis , mathematics
We analyse earthquakes recorded at The Geysers geothermal field in California, an area where industrial activity induces seismicity. The seismicity is characterized by the seismic b ‐value and D , the fractal dimension of earthquake hypocentres measured from sliding windows containing 200 events. We study a group of events strongly clustered around an injection well. Over most of the time period examined we find a positive correlation between b and D . However, during the initiation of injection into a new well we find instead a negative correlation. The differences in correlation are statistically significant at the 1 σ level but only marginally so at the 2 σ level. These results provide evidence for a transient change in the seismic mechanisms operating, and may be explained by a change from conditions of slow stress loading to rapid loading as a result of the build‐up of the rate of water injection into the reservoir.