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WITHDRAWN Use of Repeating Earthquakes to Discriminate Slow Earthquakes in the Central Pacific Subduction Zone of Costa Rica

Description: 

WITHDRAWN The complexity and dynamics of subduction zones exhibit a mix of fast (seismic) and slow (aseismic) slip, whose physical interaction strongly influences fault system behavior and can promote the nucleation of potentially catastrophic events. Therefore, understanding how seismic and aseismic processes interact is crucial to improve earthquake hazard assessment. Repeating earthquakes (RE), events with highly similar waveforms and magnitudes that rupture the same fault patch at different times, provide a unique opportunity to advance our understanding of this complex relationship. Using the local seismic network and modern template-matching techniques, we studied 20 RE families, with a total of 430 events ranging from 2010 to 2023, located in the Central Costa Rica Subduction Zone, one of the most seismically active and heterogeneous regions in the country due to the subduction of seamounts and the presence of slow slip events (SSEs) every 22 months or less. We show how the spatiotemporal distribution of RE correlates with the occurrence of large earthquakes (M > 6.0) and well-characterized SSE episodes. Additionally, the emergence of localized, uncatalogued SSEs with magnitudes below the detection threshold of GNSS—but observed at the two closest stations—is accompanied by tremors and the continued rupture of an abundant RE family including hundreds of events. The slip rate, calculated from RE assuming constant stress drop, agrees with the previously measured plate convergence rate. Our results suggest that, along with tectonic tremor, RE represents the seismic manifestation of SSEs and could be used as markers to indicate their occurrence, duration, and spatial distribution, especially in areas where GNSS networks are non-existent, lack resolution, or when their magnitude falls below the minimum required for standard identification and localization techniques.

Session: Predictability of Seismic and Aseismic Slip: From Basic Science to Operational Forecasts [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Nahomy

Student Presenter: Yes

Invited Presentation: 

Poster Number: 40

Authors