Abstract
In the present work, a multiscale post-seismic relaxation mechanism, based on the existence of a distribution in relaxation time, is presented. Assuming an Arrhenius dependence of the relaxation time with uniform distributed activation energy in a mesoscopic scale, a generic logarithmic-type relaxation in a macroscopic scale results. The model was applied in the case of the strong 2015 Lefkas Mw6.5 (W. Greece) earthquake, where continuous GNSS (cGNSS) time series were recorded in a station located in the near vicinity of the epicentral area. The application of the present approach to the Lefkas event fits the observed displacements implied by a distribution of relaxation times in the range τmin ≈ 3.5 days to τmax ≈ 350 days.
Highlights
Earthquake rupture creates static stress changes within the lithosphere that are large enough to produce transient deformation that can be observed on the Earth’s surface
Since different crack sizes have different activation energy, the associated relaxation processes operate at different timescales [22], indicating an intrinsic organization [23] with a distribution of relaxation times, instead of the use of a single one. The latter implies that post-seismic relaxation could be viewed as the superposition of several different relaxation times, each one activated in different mesoscopic domains of the macroscopic relaxed seismic volume
In the present work the post-seismic relaxation is viewed as a superposition of several different relaxation times, each one activated in different mesoscopic domains of the macroscopic relaxed seismic volume
Summary
Earthquake rupture creates static stress changes within the lithosphere that are large enough to produce transient deformation that can be observed on the Earth’s surface. The after-slip mechanisms are localized and follow logarithmic decay [4,7], while the viscoelastic one is supported by a bulk deformation process and exhibits exponential decay [8,9,10]. Logarithmic deformation could be explained by an exhaustion process, which is based on the assumption that the number of sources of strain-producing events evolve according to a thermally activated process, in which the activation energy is stress dependent [12]
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