Distinct yet Comparable Scaling Relations for Slow Slips and Fluid-Induced Seismic Swarms

Slip transients cover a wide range of scales in length, duration, moment, slip among others. They also exhibit a rich spectrum of behaviors like slow aseismic slip in subduction zones or transform faults, or faster and potentially devastating ruptures in the case of earthquakes. Earthquake swarms, either occurring in natural tectonic context or due to anthropogenic fluid injections at depth, have been found to exhibit another peculiar behavior: they show a global migration, sometimes accompanied by faster bursts, and could result from the interplay between fluid processes, aseismic slip and seismicity.

 

In this study, we synthesize findings from the literature on slow slip events and earthquakes, integrating insights from our research on earthquake swarms. We examine how swarms conform to or deviate from established scaling relations for seismic phenomena. Specifically, we compare earthquake swarms, slow slip events, and earthquakes in terms of moment and duration, and analyze the migration or rupture velocities of swarms and slow slip events relative to moment.

 

We highlight two different but parallel behaviors among these sequences: one linked to slow-slips, with elevated migration velocities and moments, and the other related to fluid-induced processes, featuring lower velocities and moments. These results provide metrics for distinguishing between the drivers of earthquake swarms —both natural and injection-induced— and their connections to fast seismic transients and foreshocks. This work also highlights promising directions for instrumentation and the study of slow and aseismic slip transients.