Structural Control on Megathrust Rupture and Slip Behavior: Insights From the 2016 Mw 7.8 Pedernales Ecuador Earthquake

Lillian Soto-Cordero, Anne Meltzer, Eric Bergman, Mariah Hoskins, Joshua C. Stachnik, Hans Agurto-Detzel, Alexandra Alvarado, Susan Beck, Philippe Charvis, Yvonne Font, Gavin P. Hayes, Stephen Hernandez, Colton Lynner, Sergio Leon-Rios, Jean Mathieu Nocquet, Marc Regnier, Andreas Rietbrock, Frederique Rolandone, Mario Ruiz

Research output: Contribution to journalArticle

Abstract

The heterogeneous seafloor topography of the Nazca Plate as it enters the Ecuador subduction zone provides an opportunity to document the influence of seafloor roughness on slip behavior and megathrust rupture. The 2016 Mw 7.8 Pedernales Ecuador earthquake was followed by a rich and active postseismic sequence. An internationally coordinated rapid response effort installed a temporary seismic network to densify coastal stations of the permanent Ecuadorian national seismic network. A combination of 82 onshore short and intermediate period and broadband seismic stations and six ocean bottom seismometers recorded the postseismic Pedernales sequence for over a year after the mainshock. A robust earthquake catalog combined with calibrated relocations for a subset of magnitude ≥4 earthquakes shows pronounced spatial and temporal clustering. A range of slip behavior accommodates postseismic deformation including earthquakes, slow slip events, and earthquake swarms. Models of plate coupling and the consistency of earthquake clustering and slip behavior through multiple seismic cycles reveal a segmented subduction zone primarily controlled by subducted seafloor topography, accreted terranes, and inherited structure. The 2016 Pedernales mainshock triggered moderate to strong earthquakes (5 ≤ M ≤ 7) and earthquake swarms north of the mainshock rupture close to the epicenter of the 1906 Mw 8.8 earthquake and in the segment of the subduction zone that ruptured in 1958 in a Mw 7.7 earthquake.

Original languageEnglish (US)
Article numbere2019JB018001
JournalJournal of Geophysical Research: Solid Earth
Volume125
Issue number2
DOIs
StatePublished - Feb 1 2020

Keywords

  • aftershock sequence
  • megathrust rupture
  • subduction zone earthquakes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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    Soto-Cordero, L., Meltzer, A., Bergman, E., Hoskins, M., Stachnik, J. C., Agurto-Detzel, H., Alvarado, A., Beck, S., Charvis, P., Font, Y., Hayes, G. P., Hernandez, S., Lynner, C., Leon-Rios, S., Nocquet, J. M., Regnier, M., Rietbrock, A., Rolandone, F., & Ruiz, M. (2020). Structural Control on Megathrust Rupture and Slip Behavior: Insights From the 2016 Mw 7.8 Pedernales Ecuador Earthquake. Journal of Geophysical Research: Solid Earth, 125(2), [e2019JB018001]. https://doi.org/10.1029/2019JB018001