Priddis low-frequency seismometer test, part 2
Kevin W. Hall, Malcolm B. Bertram, Gary F. Margrave, David W. S. Eaton
CREWES acquired a low-frequency sensor comparison test dataset in 2009. The dataset was acquired using a weight drop trailer and an IVI Minivibe (2-10 Hz and 2-100 Hz linear sweeps with different sweep lengths and peak force levels) at two source points, offset by 50 meters from the ends of the north-south receiver lines. Sensors on the ground included accelerometers (DSU3 and VectorSeis), geophones (SM-24) and broadband seismometers (Trillium 240). Near-offset (50 m) traces for a single 2-100 Hz linear sweep are visually compared as 1) uncorrected, uncorrelated data, 2) converted to common units and corrected for geophone and seismometer instrument response in the velocity and acceleration of ground motion domains. Least-squares-subtraction-scalar results are also presented. System electrical noise appears to dominate signal below about 7 Hz for all systems, likely due to the long taper used for the low frequencies (< 10 Hz) and the low power used for the sweep in order to not damage the Minivibe. We appear to have a close match (other than a multiplicative term) down to at least 5 Hz for all recording systems and sensors.