This paper describes a means of combining the voltages from a three-component seismometer so as to suppress noise waves arriving randomly from al] directions and to indicate the direction of arrival of any particular wave-train, such as might be caused by an earthquake, explosion, or moving vehicle. Each of the horizontal components of motion is electronically multiplied by the vertical component, with or without phase shift, and the two resulting products are displayed as a vector pointing to the source of seismic waves. The equipment assembled to perform these operations is referred to as the Motion Product Detector. Mathematical analysis and small-scale tests of the Motion Product Detector on the Research Center grounds look promising.
Figures & Tables
Seismic Wave Propagation: Collected Works of J. E. White
This first chapter sets the stage for the later technical development of Dr. Whit’s career in applied seismics. Experiments, f’wst at the Acoustics Laboratory of the Massachusetts Institute of Technology and later at Mobil Oil and Marathon Oil, provided insight into the general problems of impedance measurements, transduction, filtering, and attenuation. These papers also serve as a bridge to show geophysicists how theft own experiments in seismology naturally interface with (indeed, arose out of) the larger world of sound measurements in air and water. These experiments demonstrate the power of geometrically constrained experiments to allow verification of approximate (and in some cases, exact) theories of sound.