GNGTS 2013 - Atti del 32° Convegno Nazionale

in Figs. 3 a, b, c illustrate the outcomes of the spatial filters application on the more interesting part of the Patigno landslide stacked section. A basic processing sequence consisting of band- pass filter (10-20-140-160 Hz), statics corrections, velocity analysis, NMO correction (30% stretch mute), AGC (25 ms), surface consistent residual statics and stack was applied to the data to obtain the section in a). An attenuation of the surface waves noise is achieved when the step of equally weighted array forming is introduced in the processing sequence, (compare frame a) with frame b)), and a further attenuation is evident when the Chebyshev weighted array is used instead (frame c). The noise attenuation in the equally weighted array stack comes with a little decrease in resolution of the upper events, an effect that do not appear in the Chebyshev weighted array stack. Frames a 1 ,b 1 ,c 1 display the same close-ups after the application of the weighted spatial filters on the receiver side (5 receivers equally weighted in b 1 ) and Chebyshev weighted in c 1 and a mute of the shortest offset traces (a 1 ,b 1 ,c 1 ). The beneficial effects of the Fig. 3 – Close-ups of the stack sections obtained after a basic processing sequence. Frames a), b) and c) compare the unfiltered data, the data after the application of the equally weighted source array, the filtered data with the weighted Chebyshev source array, respectively. Frames a 1 ), b 1 ) and c 1 ) illustrate the same close-ups where the traces at short offset are muted and where the receiver spatial array filters with equal weights (b 1 ) and optimal Chebyshev weights (c 1 ) are applied. 69 GNGTS 2013 S essione 3.1