Multifractal scaling of thermally activated rupture processes

We propose a multifractal stress activation model combining thermally activated rupture and long memory stress relaxation, which predicts that seismic decay rates after mainshocks follow the Omori law similar to1/t(p) with exponents p linearly increasing with the magnitude M-L of the mainshock. We carefully test this prediction on earthquake sequences in the Southern California earthquake catalog: we find power law relaxations of seismic sequences triggered by mainshocks with exponents p increasing with the mainshock magnitude by approximately 0.1-0.15 for each magnitude unit increase, from p(M-L=3)approximate to0.6 to p(M-L=7)approximate to1.1, in good agreement with the prediction of the multifractal model.