9725238 Beroza This research involves the development of an automated technique for obtaining very precise relative earthquake locations. Observational errors will be reduced by measuring relative P and S wave arrival times using waveform cross correlation. The improved measurements will be used as input to a joint hypocentral determination. The key challenge will be to automate this process so that it can be widely applied. The method will be used to study fault mechanics and the structure of active fault systems as expressed by microearthquake seismicity. This research is a component of the National Earthquake Hazard Reduction Program. ***
