GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 3.1 585 frequency components pertinent to the noise. It is also possible, from the wavelet spectrum, to reconstruct the trace by means of the inverse continuous wavelet transform (ICWT) (Farge, 1992; Sadowsky, 1996). If the wavelet spectrum is modified, i.e. some frequency components are zeroed, the reconstruction yields a trace characterized by the lack of the removed frequency components. This, corresponds to filter the data in the wavelet domain. Results. The presented real data are from a near surface reflection survey acquired at Luni, in Tuscany (Italy). 185 shot gathers were acquired using a 10 kg sledgehammer and a 48-channel single geophone spread as the energy source and the recording device. The sampling interval was 0.5 ms and the record length 1s. The spacing between the receivers is 2 m and 1m is the spacing adopted for the sources. More about the acquisition can be found in Tognarelli and Stucchi (2016). In Fig. 1a is illustrated an example of raw gather which is clearly contaminated by GR. Fig. 2 shows the Fig. 1 - a) Raw gather. b) Same gather after filtering in the wavelet domain. c) Difference between a) and b). Fig. 2 - Wavelet spectra of three traces extracted from the raw gather illustrated in Fig. 1a and located at offset=20 m (a), 40 m (b) and 90 m (c). In red, are highlighted the mute masks applied for the showed spectra.