| Abstract |
In recent decades, large seismic activity across different monitoring networks have been observed in the geothermal fields of Mexico, relating the seismic to exploitation operations and the hydrothermal system, leading to distinguish the activities of major impact on the generation of events. In Los Humeros from 1997 until 2008, many earthquakes were concentrated in the trace of the NE-SW faults and around the injection wells, located on the periphery of highest temperature zone in the reservoir, suggesting a close relationship between seismicity and fluid intake through injection wells. Additional to the injection and hydraulic fracturing, seismic activity has been observed related possibly to the fracturing of the rocky skeleton, a phenomenon caused by the expansion and dilation of the pores in the rock, due to variations in pressure and temperature. Los Azufres Field, analyzed during the years 2008 and 2009, the seismicity complement the structural model associating activity to the faults La Cumbre and El Chino, also showing numerous events related to the injection wells and null respect to producing wells. In Tres Virgenes Geothermal Field, the seismicity was studied from 2003 to 2010, involving much of the seismic activity to the stimulation and production testing of the last two development wells, the activity is related as well to the regional tectonic system, faults La Virgen, El Volcan, El Partido and El Cimarron, with striking accumulation in La Cuesta and El Partido, structures close to the injector and the last well drilled. Finally, related to Cerro Prieto geothermal field in Baja California, the seismicity is clustered mainly in the exploitation area and one kilometer depth of the injection and production intervals, when it comes to the geological structures, the activity it’s observed near the normal fault system (system H or Morelia) and Cerro Prieto fault. |