GNGTS 2018 - 37° Convegno Nazionale

776 GNGTS 2018 S essione 3.3 If the waveform has impulsive part, then both Morlet and Ricker wavelets are created and fitted the proper position on the waveform. The wavelet with the lowest residual is considered as the representative wavelet of the impulsive part. Residual value is calculated by subtracting the waveform energy from the created wavelet’s energy. Furthermore, we investigated the velocity spectral response of the waveform and the created wavelet (Fig. 2). Results show that created wavelets can mimic the impulsive part of the waveform. We reached this conclusion by checking the spectral amplitudes on higher periods where impulsive signals generally located. Fig. 2 - Pseudo spectral velocity graphs of (a) 1992 Landers Earthquake, Yermo Fire Station signal (red) and obtained Ricker wavelet signal (black), (b) 1999 Chi-Chi Taiwan Earthquake, TCU039 Station signal (red) and obtained Ricker wavelet signal (black), (c) 1980 Irpinia Earthquake (M w = 6.9), STN Station (epicentral distance = 30.35 km) signal (red) and obtained Ricker wavelet signal (black) and (d) 2016 Amatrice Earthquake (M w = 6.5), CLO Station (Epicentral distance = 11.5 km) signal (red) and obtained Ricker wavelet signal (black). In all figures, the blue line represents the period of the pulse. Pulse at PGV Pulse at other place Ricker Wavelet 290 26 3 rd order Morlet Wavelet 4 0 4 th order Morlet Wavelet 0 0 Strike Slip Fault 111 10 Normal Fault 62 7 Reverse Fault 121 9 Tab. 1 - Results of the earthquake signals in our database. First 3 rows show number of pulse-shaped signals that are mimicked better with the given wavelet types. Rest of the rows are indicating the fault mechanism that created the earthquake signal. Column indicate the part of the signal that impulsive behavior occurred.