Dual Role of a Subducted Seamount in Megathrust Rupture Initiation and Rupture Barrier
Year: 2026
Type: article
Abstract: Using high‐resolution 3D tomography and a relocated 2010–2022 earthquake catalog, we identify a seamount at 20–25 km depth beneath the Mompiche–Cojimíes region in the coastal forearc of Ecuador. This provides a rare, well‐resolved example of seamount preservation at these depths. The seamount coincides with a low interseismic‐coupling corridor and shows persistent seismicity along its flanks. Rupture of the 2016 Mw 7.8 Pedernales earthquake initiated on the southern flank of the seamount. The rupture propagated south, but northward propagation was arrested near the decoupled, aseismic crest, illustrating the dual mechanical behavior of the seamount. After the megathrust earthquake, seismicity migrated downdip, particularly along the eastern margin. These results show the influence of subducted topography on coupling, seismicity, and rupture segmentation in megathrust systems.
Source: Geophysical Research Letters
DOI: 10.1029/2025gl119106
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,190
Awards: Enabling Discoveries in Multiscale Earth System Dynamics: Seismological Facility for the Advancement of GEoscience (SAGE), Collaborative Research: 3D Imaging of Controls on Subduction Zone Megathrust Rupture and Slip Behavior, Collaborative Research: HIPER - 3D Onshore-Offshore Imaging of Controls on Subduction Zone Megathrust Rupture and Slip Behavior, NNSFGEO-NERC: Collaboration: The Role OF Asperities and Slow Slip in Subduction Zone Rupture and Aftershock Sequences: Insights from the 16 April 2016 Pedernales Ecuador Earthquake
OpenAlex ID: W7134180271