Accession Number : ADA257703


Title :   Multitaper Cross-Spectral Analysis and Related Studies of NTS explosions


Descriptive Note : Technical rept. 1 Apr-23 Aug 1992


Corporate Author : TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS


Personal Author(s) : Gupta, Indra N ; Davis, J P ; McElfresh, Thomas W


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a257703.pdf


Report Date : 29 Oct 1992


Pagination or Media Count : 39


Abstract : During this report period, software for determining the delay time between two waveforms was further developed and tested on real data. The main improvement was use of the multitaper method of spectral analysis which has been shown to yield better results than standard single-taper procedures. This procedure constitutes a significant improvement over all previous studies of cross-spectral analysis based on the use of a single taper. An application to closely-located Yucca Flat explosions recorded at four stations showed significant improvement over single-taper results. Inter-source coherence for Pn was found to be significantly greater when the two sources lay along the direction of wave propagation than when perpendicular to it. Mean velocities along the four source- receiver paths were found to be stable and significantly different, suggesting that propagation velocities may vary considerably from one path to another. It seems therefore that at least a part of the observed location errors are due to the assumption of a uniform path-independent velocity model in the computation of location. Analysis of data from two closely located explosions suggests that the cross-spectral method may also be used to determine very small differences (of the order of 1%) between propagation velocities of regional phases.


Descriptors :   *UNDERGROUND EXPLOSIONS , *NUCLEAR EXPLOSION TESTING , *TAPER , *NUCLEAR EXPLOSION DETECTION , VELOCITY , COMPUTER PROGRAMS , POSITION(LOCATION) , MODELS , WAVEFORMS , WAVE PROPAGATION , ERRORS , PRIMARY WAVES(SEISMIC WAVES) , TRAVEL TIME , MEAN , STANDARDS , DELAY , RECEIVERS , SPECTRA , DEPTH , COHERENCE , PATHS , EIGENVECTORS , EXPLOSIONS


Subject Categories : Nuclear Weapons


Distribution Statement : APPROVED FOR PUBLIC RELEASE