GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Figure 5. Variance of the stacked atenuaton tme histories of Figure 5 calculated on adjacent subsets of 40 data points. Note that, at the end of the previous seismic cycle, the San Simeon earthquake completely shuts of the variance of the atenuaton tme histories on both sides of the fault. Before being shut-of, variance shows an increasing trend on the Pacifc side of the fault. During the current cycle, in the decade 2010-2020, a similar increasing trend is observed on the variance on the Pacifc side of the SAF. SS, PA and NA indicate, respectvely, the occurrences of the San Simeon, Parkfeld, and Napa earthquakes. Comparing this Figure with Figure 2 we see a correspondence between the variance drop and a signifcant reducton of tremor actvity in 2020, suggestng that the seismic atenuaton (and possibly the main seismic actvity) is modulated by the NVT rate.