GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 mentoned bands. Of great interest is the bifurcaton of the stacked atenuaton tme histories that can be observed startng 6-8 weeks before the September 28, 2004 Parkfeld mainshock. No bifurcaton characterizes intermediate frequency bands. Figure 4. Stacked-averaged estmates of tme histories of the variaton of the atenuaton parameter in two frequency bands: 2.0-5.0 Hz (black, lef scale) and 30-50 Hz (red, right scale). In A and B the stacked-averaged values of the atenuaton parameter are ploted in a three-year tme window (01/01/2002 through 01/01/2005), whereas C and D show the stacked-averaged atenuaton tme histories between 01/01/2005 and the fall of 2023. ( δ ( Q −1 S ( t , f ) ) )