Shallow versus deep slow slip events on the Nicoya megathrust observed with GPS
Abstract
Slow slip events (SSEs) represent a distinct aseismic strain release process that occurs in many subduction zones. Observation and modeling of this process can be used to characterize and potentially forecast future damaging earthquakes or tsunamis in these regions. Quantifying the amount of slip by SSEs, over an entire earthquake cycle, will help estimate the potential amount of slip stored and which will be release to close a earthquake cycle. Continuous Global Positioning System (GPS) data collected from 2002-2020 by a regional network were used to study SSEs in and near the Nicoya Peninsula of Costa Rica. SSEs occur in both shallow (~10 km) and deep (~35 km) portions of the plate interface, but are characterized by different behaviors: 1) Deep SSEs last longer and have larger magnitudes; 2) Shallow SSEs appear to be more frequent; 3) Deep SSEs are more predictable, including recurrence time, location and magnitude. Based on available data, deep SSEs occurred every 21.6±2.5 months, with moment magnitude equal to Mw 6.8-6.9, and both the recurrence interval and magnitude were unchanged by the 5 September 2012 Mw 7.6 earthquake. Due to limited data coverage, some shallow SSEs cannot be resolved by existing measurements, thus demanding better instrumental constraints.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMT003.0018X
- Keywords:
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- 7215 Earthquake source observations;
- SEISMOLOGY;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS;
- 8164 Stresses: crust and lithosphere;
- TECTONOPHYSICS