| Abstract |
Seismic activity in the Cerro prieto area (Baja California, Mexico) is supposed to be high, due to the proximity of the Cerro Prieto and Imperial active faults. Records of seismicity are usually reported in USGS-Caltech and RESNOM catalogues and local arrays are continuously monitoring seismicity since august 1994. Reinjection of geothermal fluid began in 1989. Comparison between the USGS-Caltech catalogue and records of the variation of injection flow rate from 1988 to 1996 suggests that a midrange (Le. several months) correlation could exist between changes in global flow rate during winter and events of magnitude larger than MI>3 occurring the following summer. From August 1994 to December 1995, seismic monitoring with a local array (5 analogical recorders) allowed better hypocenter determinations. One case of short-range spatial and temporal correlation was found between a sharp increase of flow rate in well 303 and an event located close by, but at more than 4 km depth. Since February 1996, monitoring is carried out by a digital array (5 stations), operated by the Comision Federal de Electricidad, which allows better hypocentral determinations. |