Orientation determination

The procedure was simply to demean and lowpass filter the data at less than 1 Hz and then rotate the data from the sensors
to match the data from the surface. Error was calculated by the difference between the seismograms. The covariance
matrix was also calculated. Comparisons were also made of the particle motion from earthquakes of known location
to verify that particle motion seemed correct. Both sets of surface sensors were used for comparison. The results
within 2 degrees of each other (103 and 101 degrees, 349 and 348 degrees).

matlab script

Plot of error versus azimuth. The accuracy of the 45 m sensor (blue) is probably better than that of the 90 m sensor.