Hoskins M. C. auteur aut IRD Meltzer A. auteur aut IRD Font Yvonne auteur aut IRD Agurto-Detzel H. auteur aut IRD Vaca S. auteur aut IRD Rolandone F. auteur aut IRD Nocquet Jean-Mathieu auteur aut IRD Soto-Cordero L. auteur aut IRD Stachnik J. C. auteur aut IRD Beck S. auteur aut IRD Lynner C. auteur aut IRD Ruiz M. auteur aut IRD Alvarado A. auteur aut IRD Hernandez S. auteur aut IRD Charvis Philippe auteur aut IRD Régnier Marc auteur aut IRD Leon-Rios S. auteur aut IRD Rietbrock A. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Megathrust ruptures and the ensuing postseismic deformation cause stress changes that may induce seismicity on upper plate crustal faults far from the coseismic rupture area. In this study, we analyze seismic swarms that occurred in the north Ecuador area of Esmeraldas, beginning two months after the 2016 M-w 7.8 Pedernales, Ecuador megathrust earthquake. The Esmeraldas region is 70 km from the Pedernales rupture area in a separate segment of the subduction zone. We characterize the Esmeraldas sequence, relocating the events using manual arrival time picks and a local a-priori 3D velocity model. The earthquake locations from the Esmeraldas sequence outline an upper plate fault or shear zone. The sequence contains one major swarm and several smaller swarms. Moment tensor solutions of several events include normal and strike-slip motion and non-double-couple components. During the main swarm, earthquake hypocenters increase in distance from the first event over time, at a rate of a few hundred meters per day, consistent with fluid diffusion. Events with similar waveforms occur within the sequence, and a transient is seen in time series of nearby GPS stations concurrent with the seismicity. The events with similar waveforms and the transient in GPS time series suggest that slow aseismic slip took place along a crustal normal fault during the sequence. Coulomb stress calculations show a positive Coulomb stress change in the Esmeraldas region, consistent with seismicity being triggered by the Pedernales mainshock and large aftershocks. The characteristics of the seismicity indicate that postseismic deformation involving fluid flow and slow slip activated upper plate faults in the Esmeraldas area. These findings suggest the need for further investigation into the seismic hazard potential of shallow upper plate faults and the potential for megathrust earthquakes to trigger slow-slip and shallow seismicity across separate segments of subduction zones. specialized triggered seismicity upper plate deformation postseismic deformation megathrust rupture earthquake swarm aftershocks EQUATEUR 066 553 116620 [13 p.] 2021 0012-821X https://www.documentation.ird.fr/hor/fdi:010080457 10.1016/j.epsl.2020.116620 0012-821X [F B010080457] https://www.documentation.ird.fr/hor/fdi:010080457 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers21-01/010080457.pdf IRD - Base Horizon / Pleins textes 2021-02-08 2025-02-24 fdi:010080457 fre