Mapping Seismic Activity in Geothermal Regions

Abstract

Techniques to three dimensionally located sources of seismic ground noise have been developed and successfully applied to data recorded in several geothermal regions. It is believed that these techniques represent a major improvement over conventional ground noise surveys and can significantly enhance one's ability to both explore for and delineate features of geothermal systems. This approach is based on the assumption that the dominant sources of ground noise in these regions are likely to originate from the dynamics of hot fluids, vapors, and active faults associated with the geothermal system. In the analysis of data recorded at Long Valley, ground noise sources coinciding with know faults and hot springs were detected. Both the field an signal analysis techniques were developed specifically of this application and substantially reduce problems encountered in conventional ground noise surveys, such as ground amplification and interference of cultural noise sources. The signal analysis involves use of nonlinear array processing techniques as well as techniques allowing for inconsistencies in the regional geology.