HR: 1330h
AN: S52D-0167    [PDF]
TI: Enhancement of Fourier Amplitude Spectra by Composing 3-Component Records
AU: * Noh, M
EM: mhnoh@kins.re.kr
AF: Korea Institute of Nuclear Safety, Kusong-dong 19, Yusong-ku, Taejon, 305-338 Korea, Republic of
AU: Choi, K
EM: k116ckr@kins.re.kr
AF: Korea Institute of Nuclear Safety, Kusong-dong 19, Yusong-ku, Taejon, 305-338 Korea, Republic of
AU: Kim, T
EM: gawaii@hanmail.net
AF: Korea Institute of Nuclear Safety, Kusong-dong 19, Yusong-ku, Taejon, 305-338 Korea, Republic of
AB: Modern seismographs produce a large amount of high-quality digital seismic data. They can accurately record the small earthquakes of magnitude down to ? or less. In case of the small earthquake, however, the majority of the data are abandoned after just picking P- or S-wave arrival times because of low signal-to-noise ratios. We suggest a method to enhance the seismic signal out of the noise for the spectral analysis of the small earthquake data. The method is based on the composed amplitude spectrum that is calculated by taking the norm of 3-component complex vectors of the Fourier-transformed seismic records. The composed amplitude spectrum provides two advantages. First, it enhances the shape of the Fourier amplitude spectrum to provide more accurate estimates of seismic moment, corner frequency, and high-frequency decay trend than the single component amplitude spectrum. Second, it eliminates the vector-partition terms appearing in the single components to provide a more accurate estimate of seismic moments. The latter is especially useful when dealing with the seismic waves of a wide range take-off angle such as Lg waves. Unlike some previous studies (e.g., Andrews, 1986; Snoke, 1987), our method improves the shapes of the Fourier amplitude spectra themselves. Therefore, our method can accommodate all the techniques proposed by the previous studies.
DE: 7212 Earthquake ground motions and engineering
DE: 7215 Earthquake parameters
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2003 Fall Meeting