Seismic Evidence for Cocos Slab Tearing and Nazca Slab Emplacement in the Southern Costa Rican Subduction Zone

A flat interface at 40–60 km depth beneath the Talamanca Range, identified through seismic receiver function analysis, reveals the stagnation of the Nazca plate since approximately 8 million years ago. This geological feature likely blocked melt upwelling, explaining the cessation of arc volcanism in the region while coinciding with the later uplift of the Talamanca Range due to subduction of the Cocos Ridge. The study employed a refined Dip Direction Searching method on teleseismic waveforms from 17 broadband stations, imaging a northeast-dipping Moho interface of the Cocos slab that may have undergone tearing, providing critical insights into the dynamic processes governing subduction zone volcanism and tectonics.

Feng, M., Wei, S., Chen, L., Wang, X., Protti, M., & Feng, L. (2025). Seismic Evidence for Cocos Slab Tearing and Nazca Slab Emplacement in the Southern Costa Rican Subduction Zone. Geophysical Research Letters, 52(20). Portico. https://doi.org/10.1029/2025gl116194