A comparison of seismicity at The Geysers and in the surrounding region indicates that the rate of seismicity at The Geysers is 45 times the regional rate and that clustering of events in space and time is more prevalent in the region area than at The Geysers. Temporally clustered seismic events that occurred at The Geysers from September 1975 through September 1976 appear linked to regional temporal clusters located at the southern end of Clear Lake. During this period, a characteristic 2- to 6-day time lapse separated temporal clusters at The Geysers from those at Clear Lake. The two areas where these correlated clusters occurred lie on either side of a presumed magma body. Correlation between clusters in the two areas disappears after September 1976. During the period of correlated seismic episodes, regional stress changes may have been transmitted between the two areas by aseismic creep.

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