Verifying the Coherency Transfer Function Ground Motion Predictions for Multiple Underground Explosions

The coherency transfer function (CTF) is a method for summing seismograms from multiple nearly coherent sources by using a frequency domain transformation. Ground motion predictions for the nuclear explosive Rio Blanco experiment are calculated for peak vector amplitudes of acceleration, velocity, and displacement and are compared to the Rio Blanco data and the results of other prediction techniques. Predictions of amplitudes are higher than experimental results by a few percent for acceleration and displacement and by 20% for velocity. Data regression slopes are ∼12% greater than predicted values for acceleration but <5% greater for displacement and velocity. CTF predictions are found to agree with experimental results as good as or better than values predicted by other methods.