DTIC ADA235579: Analysis of High Frequency Seismic pdf

DTIC ADA235579: Analysis of High Frequency Seismic

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The aim of this research was to characterize the high frequency content of noise and signals, and to develop methods of discriminating between mine blasts and other sources using high frequency seismic data. Data for these studies came from the NORESS small aperture array in Norway and its high frequency (up to 125 Hz) central element. Major research results include: (1) Upper frequency limits of teleseismic P-wave spectra for events recorded at the NORESS high frequency element were between 5 and 20 hz; (2) Path spectra for explosions from Balapan follow the attenuation models proposed by other authors (apparent t bar =0.14) up to 15 Hz, but from 15 to 20 Hz, the attenuation of the Balapan-NORESS path spectra is greater than that extrapolated from previous models; (3) Scatter in delay times between successive blasts of a ripple-fired explosion have a deteriorating effect on spectral modulation; (4) For the few blasts that are ideal, i.e., have no or negligible errors in time delays, the delay time between shots as well as the number of shots in the explosion can be estimated; (5) The shape of wavefronts from Balapan explosions as recorded at NORESS were nearly identical for

33 events studied; and (6) Wavefronts from events in the N.E. section of the Balapan test site were characterized by a consistent tilt with respect to the wavefronts measured from events in the S.W. section of the test site

• Creator/s: Defense Technical Information Center
• Date: 1/31/1991
• Year: 1991
• Book Topics/Themes: DTIC Archive, Israelsson, Hans, SCIENCE APPLICATIONS INTERNATIONAL CORP (SAIC) ARLINGTON VA CENTER FOR SEISMIC STUDIES, *TARGET DISCRIMINATION, *EXPLOSION EFFECTS, *SEISMIC DATA, MODELS, SHAPE, WAVEFORMS, PATHS, EXPLOSIONS, SEISMIC DETECTION, TIME, SPECTRA, LONG RANGE(DISTANCE), DELAY, ATTENUATION, EARTHQUAKES, NORWAY, MODULATION, ANTENNA ARRAYS, TEST FACILITIES, WAVEFRONTS, ANTENNA APERTURES, SEISMIC ARRAYS, MINES(ORDNANCE), FREQUENCY STANDARDS, HIGH FREQUENCY, NORTHERN EUROPE, NUCLEAR EXPLOSIONS, TIME INTERVALS

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