Diffusional earthquakes and their slip-distance scaling

TL;DR

This paper presents a unified scaling relation for diffusional earthquakes, linking their seismic energy, slip distance, and active area evolution, revealing a distinct class of earthquakes with predictable energy limits.

Contribution

It introduces a novel diffusional constant-slip model that explains the scaling behavior of diffusional earthquakes and their energy constraints.

Findings

Seismic moment and active area trajectories align across different earthquake types.

Diffusional earthquakes follow a universal scaling law explained by a constant-slip model.

Final seismic energy is determined by slip distance in this new class of earthquakes.

Abstract

The final size of an earthquake typically cannot be predicted from its ongoing seismic radiation. Expanding observations reveal distinct exceptions, such as slow earthquakes, injection-induced seismicity, and earthquake swarms, in which fault slip has an upper bound. A common thread among these anomalies is the diffusive migration of their active areas. Here, we report a unified scaling relation for these diffusional earthquakes. By tracking prolonged earthquake swarms in Northeast Japan, we constrained the time evolution of their active seismicity areas and cumulative seismic moments. Their moment-duration trajectories coincide with the final states documented for global swarms and induced seismicity across various scales. When plotted as seismic moment versus seismicity area, their trajectories collapse onto those of slow earthquakes, uniformly explained by a diffusional constant-slip model. This constant-slip scaling carves out a unique class of diffusional earthquakes, where the final available seismic energy is predetermined by slip distance.