The source scaling and seismic productivity of slow slip transients.

Luigi Passarelli,Eleonora Rivalta,Sigurjón Jónsson,Paul Antony Selvadurai

doi:10.1126/sciadv.abg9718

Abstract

Slow slip events (SSEs) represent a slow faulting process leading to aseismic strain release often accompanied by seismic tremor or earthquake swarms. The larger SSEs last longer and are often associated with intense and energetic tremor activity, suggesting that aseismic slip controls tremor genesis. A similar pattern has been observed for SSEs that trigger earthquake swarms, although no comparative studies exist on the source parameters of SSEs and tremor or earthquake swarms. We analyze the source scaling of SSEs and associated tremor- or swarm-like seismicity through our newly compiled dataset. We find a correlation between the aseismic and seismic moment release indicating that the shallower SSEs produce larger seismic moment release than deeper SSEs. The scaling may arise from the heterogeneous frictional and rheological properties of faults prone to SSEs and is mainly controlled by temperature. Our results indicate that similar physical phenomena govern tremor and earthquake swarms during SSEs.

Highlights

Slow slip events (SSEs) are fault ruptures [1,2,3] that are too slow to excite detectable seismic waves [4]
Ordinary earthquakes and/or tremors associated with SSEs are interpreted as localized brittle failure on small-scale asperities triggered by the ongoing aseismic slip front [7, 8]
The swarmgenic SSEs (SG-SSEs) and tremorgenic SSEs (TG-SSEs) were selected by considering the seismic activity during the ongoing aseismic slip phase

Summary

INTRODUCTION

Slow slip events (SSEs) are fault ruptures [1,2,3] that are too slow to excite detectable seismic waves [4]. Fault zones experiencing SSEs exhibit other forms of strain release as earthquake swarms [swarmgenic SSEs (SG-SSEs)] [5,6,7] and/or clusters of low- and very-low-frequency earthquakes [8], embedded in episodic or continuous nonvolcanic tremor [tremorgenic SSEs (TG-SSEs)] [5, 9] These seismic phenomena correlate spatially and temporally with the underlying SSE [10], and there is growing evidence to indicate that they can be modulated with the strain rate imposed by the SSE [7, 11,12,13]. We examine patterns in duration, hypocenter migration, and rupture velocity and discuss their scaling within the context of previously published scaling behavior for ordinary and slow earthquakes

RESULTS

Methods and fig

DISCUSSION

MATERIALS AND METHODS