Influence of Scattering on Seismic Waves
Scientific rept. no. 1, 1 Feb-31 Jul 1986
MASSACHUSETTS INST OF TECH CAMBRIDGE EARTH RESOURCES LAB
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Tests have been carried out to find sources of noise and velocity bias in a new array analysis method, the wavenumber spectrum, which has been used at NORESS to detect diffuse components of teleseismic coda. Noise problems have been analysed by using subarrays and identified as being due to loss of coherence between signals at sensors of given spacing as frequency increases. Velocity bias has been investigated using synthetic signals and concluded that the full array should be used in the frequency range 1-2.5 Hz, the array less the outer ring for 2.5-5 Hz and the array less the two outer rings for 5-10 Hz, In addition, a preliminary report is given on the use of ultrasonic modeling to investigate coda. Keywords Seismic arrays Norway Seismic spectra Seismic noise Frequency-wavenumber spectrum Coherency.