DTIC ADA219370: Measurements of High Frequency Seismic pdf

DTIC ADA219370: Measurements of High Frequency Seismic

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Except for its very onset, the P wave of earthquakes and chemical explosions observed at two narrow-aperture arrays on hard rock sites in the Adirondack Mountains have a nearly random polarization. The amount of energy on the vertical, radial and transverse components is about equal over the frequency range 5-30 Hz, for the entire seismogram. The spatial coherence of the seismograms is approximately exp(-cf delta x), where c is in the range 0.4 to 0. 7 km 1/km 1/Hz, f is frequency and delta X is the distance between array elements. The spatial coherence is approximately independent of component, epicentral azimuth and range, and whether P or S wave coda is being considered, at least for propagation distances between 5 and 170 km. These results imply a strongly and three-dimensionally heterogeneous crust, with near-receiver scattering in the uppermost crust controlling the coherence properties of the waves

• Creator/s: Defense Technical Information Center
• Date: 12/4/1989
• Year: 1989
• Book Topics/Themes: DTIC Archive, Menke, William H, LAMONT-DOHERTY GEOLOGICAL OBSERVATORY PALISADES NY, *SEISMIC WAVES, *ACOUSTIC MEASUREMENT, HIGH FREQUENCY, MILITARY FACILITIES, SURFACE WAVES, COHERENCE, EXPLOSIONS, ARRAYS, ROCK, SEISMIC DATA, WAVE PROPAGATION, CHEMICAL REACTIONS, HARDNESS, RADIATION HARDENING, TRANSVERSE, SPATIAL DISTRIBUTION, POLARIZATION

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