Abstract
Temporal changes in afterslip displacement rate associated with interplate earthquakes are investigated using a constitutive law for the viscoelastic behavior of rocks. The law is based on irreversible thermodynamics with internal state variables and is derived as the relaxation modulus following a temporal power law that emerges as the collective dynamics of internal states with respective relaxation times at various time-scales. The constitutive law can represent the transient behavior in response to sudden changes in stress and strain rate, as well as the steady-state behavior of rocks. Analysis of afterslip (cumulative displacement) time series estimated from the seismic moments of small repeating earthquakes in the northeastern Japan subduction zone shows that the temporal change in afterslip follows a temporal power law. This finding suggests that afterslip comprises many transient responses associated with seismic events of various sizes.
