MULTICOMPONENT STRAIN SEISMOGRAPH

Earthquake data and phase and amplitude responses measured at both the fixed and free ends of the horizontal strain seismometer show no discrepancies that would explain the apparent loss of motion between the ends during calibration. The capability of the long-period horizontal strain and inertial seismographs to operate as a matched pair has been demonstrated. The ability of the long-period strain directional array to discriminate between surface wave arriving simultaneously from different epicenters was also successfully demonstrated. A comparison of data from vertical strain seismometers interchanged in the steel-cased and plastic-cased boreholes indicates the problem of low coherence of strain signals between the two boreholes is caused by one of the strain instruments rather than differences in the boreholes. A seismic model for Wichita Mountains Seismological Observatory WMSO was hypothesized for the longitudinal wave velocity and for the shear wave velocity from the surface to below the Mohorovicic discontinuity. An evaluation is given of the variable-capacitance transducer as a calibration monitor r and as a transducer for recording seismic data.