Temperature controls the episodic dynamics of deep slow slip

Area of Science:

• Geophysics
• Tectonics
• Seismology

Background:

• Tectonic plate boundaries exhibit deformation that transitions from shallow frictional sliding to deep viscous flow with increasing depth.
• Understanding this transition zone is crucial for comprehending earthquake mechanics and plate motion.

Purpose of the Study:

• To investigate the temporal characteristics of slow slip events in the transition zone between frictional and viscous regimes at four distinct plate boundaries.
• To determine how recurrence intervals and durations of slow slip vary with depth and correlate with seismic activity.

Main Methods:

• Utilized recurring swarms of low-frequency earthquakes as natural clocks to measure slow slip event timing.
• Analyzed recurrence intervals and durations of slow slip across different depths at four major plate boundaries.

Main Results:

• Observed a systematic decrease in slow slip recurrence intervals and durations with increasing depth.
• Calculated an average slow slip rate of 7 ± 2 mm/d, independent of depth, across all studied plate boundaries.
• Found that slow slip dynamics occur within a narrow, common temperature range across different plate boundaries.

Conclusions:

• Deep slow slip events are likely caused by the episodic unjamming of faults due to frictional heterogeneities.
• The relaxation of these frictional patches is modulated by the surrounding temperature-dependent viscous material.
• This mechanism provides a unified explanation for deep slow slip dynamics across various tectonic settings.