Accession Number : ADA149574


Title :   Seismic Observation of Infrasonic Signals


Descriptive Note : Final rept. 15 Jul 1983-14 Jul 1984


Corporate Author : TELEDYNE GEOTECH GARLAND TX


Personal Author(s) : Swanson, J G ; Woerpel, J C


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a149574.pdf


Report Date : 01 Nov 1984


Pagination or Media Count : 96


Abstract : A sliding pure-state filter attenuated wind-induced noise recorded by individual elements of a four-element microbarograph array an average of 22 dB. Summation of the processed microbarograms yielded an additional 5 dB attenuation, whereas summation of the unprocessed microbarograms attenuated the noise 6 dB relative to the individual microbarograms. A sliding pure-state filter yielding separate estimates of linearly and elliptically polarized arrivals, applied to the outputs of three-component, long-period inertial seismographs at a site near McKinney, Texas, and at Seismic Research Observatories ANMO, BOCO, and GRFO detected infrasonic signals from five eruptive sequences of E1 Chichon volcano. Application of the pure-state filter improved the signal-to-noise ratio of the seismically detected infrasonic signals an average of 14 dB. A combination of adaptive beam forming and pure- state filtering applied to the outputs of the seven elements of the NORSAR three-component, long-period array marginally detected an infrasonic signal from the largest E1 Chichon eruption.


Descriptors :   *INFRASONIC RADIATION , *MICROBAROMETRIC WAVES , *SEISMIC WAVES , NOISE(SOUND) , OBSERVATION , SEISMIC ARRAYS , SIGNAL PROCESSING , SIGNAL TO NOISE RATIO , VOLCANOES , WIND


Subject Categories : Seismology
      Acoustics


Distribution Statement : APPROVED FOR PUBLIC RELEASE