An approach to seismic correction which includes wavelet de-noising

This paper begins with a brief introduction to some methods used to correct seismic data [1,2,3]. It describes standard methods of de-convolving instrument and structural responses from seismic accelerograms. These are the convolution of ground motion with the transfer function of the recording instrument and structure on which the instrument is mounted. The instrument response can be deconvolved in the time or frequency domain to recover an estimate of the ground motion of the seismic event. This is usually followed by a band-pass filtering of the data, however this removes any ground motion outside the band and hence the accelerograms may not adequately represent an estimate of true ground motion. It is proposed therefore to use wavelet [12] de-noising [11] as an alternative to band-pass filtering. The denoising removes low and high frequency corrupting signals but retains relevant data giving a better estimate of true ground motion. Some sample seismic signals are threshold de-noised using the stationary wavelet transform (SWT) and compared with the more standard band-pass filtering techniques. The paper compares power spectral plots and the total acceleration response spectra of earthquakes using the band-pass filtering and wavelet de-noising methods.