Kinematic Afterslip Patterns

TL;DR

This paper proposes a new model for afterslip that occurs on fault sections with positive residual geometric moment, explaining spatial slip patterns after large earthquakes like the 2011 Tohoku-oki event.

Contribution

It introduces an alternative explanation for afterslip based on residual geometric moment, differing from the traditional velocity-strengthening friction model.

Findings

Model exhibits exponential decay of afterslip over time.

Allows variable sensitivity to earthquake magnitude and residual geometric moment.

Partially explains spatial distribution of co- and post-seismic slip.

Abstract

Non-inertial afterslip has been inferred to occur following large earthquakes. An explanation for this slow slip phenomenon is that coseismically generated stresses induce sliding on parts of a fault surface with velocity-strengthening frictional properties. Here we develop an alternative explanation for afterslip based on the idea that afterslip may occur on any portion of a fault that exhibits positive residual geometric moment following an earthquake, including sections that ruptured coseismically. Following a large earthquake, this model exhibits exponential time decay of afterslip and allows for variable sensitivity to coseismic event magnitude and residual geometric moment. This model provides a partial explanation for the spatial relationship of co- and post-seismic slip associated with the 2011 $\mathrm{M_W}{=}9$ Tohoku-oki earthquake.