Do slow slip events trigger large and great megathrust earthquakes?

Area of Science:

• Geophysics
• Seismology
• Earthquake Science

Background:

• Slow slip events (SSEs) are hypothesized to trigger subduction zone earthquakes.
• Previous SSE examples were poorly documented, often occurring offshore with limited data.

Purpose of the Study:

• To analyze a well-recorded SSE preceding a major earthquake.
• To investigate the relationship between SSEs and subsequent megathrust rupture.
• To assess the implications for earthquake nucleation models and hazard forecasting.

Main Methods:

• Analysis of geodetic data from a slow slip event.
• Correlation of SSE characteristics with the 2012 Costa Rica earthquake.
• Calculation of Mohr-Coulomb stress changes at the hypocenter.

Main Results:

• A slow slip event migrated towards the megathrust rupture zone.
• Peak slip rates reached 5 mm/day, sustained until the mainshock.
• Observed Mohr-Coulomb stress changes at the hypocenter were minimal (0.1 bar).

Conclusions:

• The findings challenge earthquake nucleation models based on power-law acceleration and foreshocks.
• Slow slip events offer potential for short-term earthquake forecasting.
• Detailed analysis of well-recorded SSEs is crucial for understanding earthquake processes.