TY - GEN
T1 - Estimation of source parameter of microseismic events with large magnitude collected at Basel, Switzerland in 2006
AU - Mukuhira, Yusuke
AU - Asanuma, Hiroshi
AU - Niitsuma, Hiroaki
AU - Häring, Markus
AU - Deichmann, Nicholas
PY - 2010/12/1
Y1 - 2010/12/1
N2 - Occurrence of microseismic events with large magnitude, which are felt on the surface, has been recently receiving much attention as one of the practical problems in stimulation/production of HDR/HFR/EGS geothermal reservoirs. The microseismic activities with large magnitude have been also reported from some of the hydrothermal geothermal fields. Microseismic events with moment magnitude Mw exceeded 2.0 occurred in deeper and middle part of the microseismic cloud during and just after a hydraulic stimulation at Basel, Switzerland, in 2006. Three more large events (Mw>2.0) occurred in shallower part of the seismic cloud by within two months from the bleeding-off. Because of the occurrence of the large events, the project at Basel has been terminated. The authors estimated some of the seismic source parameters (fault plane solution, seismic moment, size of ruptured area, average slip along fault, and stress drop) of the large events to understand the nature of the shear slip on fractures. Spatial distribution of the hypocenter and the fault plane solution (FPS) showed that most of the FPS of the large events had nearly N-S azimuth and those for small events had NW-SE azimuth. Most of the estimated stress drops were less than 1.0MPa, while some of the large events had larger stress drop. Events with higher stress drop (>1.0MPa) showed a linear relationship between the seismic moment and the ruptured area, suggesting that "scaling law" in natural seismology stands for this data set. Observational facts indicated that control factor of the magnitude is not simply either the size of the fault area or the stress drop.
AB - Occurrence of microseismic events with large magnitude, which are felt on the surface, has been recently receiving much attention as one of the practical problems in stimulation/production of HDR/HFR/EGS geothermal reservoirs. The microseismic activities with large magnitude have been also reported from some of the hydrothermal geothermal fields. Microseismic events with moment magnitude Mw exceeded 2.0 occurred in deeper and middle part of the microseismic cloud during and just after a hydraulic stimulation at Basel, Switzerland, in 2006. Three more large events (Mw>2.0) occurred in shallower part of the seismic cloud by within two months from the bleeding-off. Because of the occurrence of the large events, the project at Basel has been terminated. The authors estimated some of the seismic source parameters (fault plane solution, seismic moment, size of ruptured area, average slip along fault, and stress drop) of the large events to understand the nature of the shear slip on fractures. Spatial distribution of the hypocenter and the fault plane solution (FPS) showed that most of the FPS of the large events had nearly N-S azimuth and those for small events had NW-SE azimuth. Most of the estimated stress drops were less than 1.0MPa, while some of the large events had larger stress drop. Events with higher stress drop (>1.0MPa) showed a linear relationship between the seismic moment and the ruptured area, suggesting that "scaling law" in natural seismology stands for this data set. Observational facts indicated that control factor of the magnitude is not simply either the size of the fault area or the stress drop.
KW - Basel
KW - HDR
KW - HFR
KW - HWR
KW - Magnitude
KW - Microseismicity
KW - Stimulation
UR - http://www.scopus.com/inward/record.url?scp=79955087858&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79955087858&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:79955087858
SN - 9781617821844
T3 - Transactions - Geothermal Resources Council
SP - 375
EP - 380
BT - Geothermal Resources Council Annual Meeting 2010, Geothermal 2010
T2 - Geothermal Resources Council Annual Meeting 2010, Geothermal 2010
Y2 - 24 October 2010 through 27 October 2010
ER -