Crustal permeability changes inferred from seismic attenuation: Impacts on multi-mainshock sequences

We use amplitude ratios from narrowband-filtered earthquake seismograms to measure variations of seismic attenuation over time, providing unique insights into the dynamic state stress in Earth’s crust at depth. Our dataset earthquakes 2016–2017 Central Apennines sequence allows us obtain high-resolution time histories (frequency band: 0.5–30 Hz) characterized by strong dilatation-induced fluctuations seismogenic depths, caused cumulative elastic drop after sequence, as well damage-induced ones shallow depths energetic surface waves. Cumulative causes negative dilatation, reduced permeability, and attenuation, whereas strong-motion waves produce an increase crack density, so permeability attenuation. In aftermath main shocks we show that M ? 3.5 occurrence vs. distance is consistent with fluid diffusion: diffusion signatures are associated changes during first days Amatrice, Visso-Norcia, Capitignano sub-sequences. hypothesize coseismic create pathways least partly responsible for triggering multi-mainshock sequences. Here anelastic fluctuates coherently our hypothesis.