9706091 Wagner This research is to investigate the use of observations made at small-aperture three-component seismic arrays as a means of measuring spatial and temporal variations in subsurface properties in active fault zones. The motivation for this study is based on the premise that the increase in stress which is presumed to precede large to moderate sized earthquakes may lead to changes is seismic parameters. The parameters of particular interest for this study are shear wave splitting, seismic coda excitation and shear wave polarization. The data will be processed using a statistical array processing algorithm that provides high-resolution estimates of the frequency, wavenumber and polarization characteristics of the coherent arrivals observed at the array. This research is a component of the National Earthquake Hazard Reduction Program. ***
