Fig. 3
Examples of the noise (blue line), observed P signal (black line), and modeled (red line) spectra for four stations LUSI, CGRP, D007, and D041of an event with ML = 3.4. In the upper panels, the normalized time series waveforms and the selected 2.56 s windows for analyses of signal and noise (dark and light gray, respectively) are displayed. t*, tt, fc, Δ, and w are the whole path attenuation, travel-time, source corner frequency, epicentral distance, and weight (representative of the quality of the signal), respectively. The comparison of the four stations shows how the slope and shape of the P signal spectrum affect the t* value and the quality weight