| Titre | Slow slip and inter-transient locking on the Nicoya megathrust in the late and early stages of an earthquake cycle |
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| Auteur | Xie, S; Dixon, T H; Malservisi, R; Jiang, Y ; Protti, M |
| Source | Journal of Geophysical Research, Solid Earth 2020 p. 1-22, https://doi.org/10.1029/2020JB020503 |
| Image |  |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200459 |
| Éditeur | American Geophysical Union |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1029/2020JB020503 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Lat/Long OENS | -86.0000 -84.0000 11.0000 9.0000 |
| Sujets | tectonique de plaques; failles, effrondrement; secousses séismiques; études séismiques; énergie sismique; levés sismiques; données sismiques; Plaque de Caribbean ; Nature et environnement; Sciences et
technologie; tectonique |
| Illustrations | cartes de localisation; graphiques; graphiques; tableaux; modèles |
| Programme | Géoscience pour la sécurité publique Tremblements de terre à la limite des plaques |
| Diffusé | 2020 10 20 |
| Résumé | (disponible en anglais seulement)
We analyzed continuous GPS data collected from 2002-2020 to characterize slow slip events (SSEs) in and near the Nicoya Peninsula, Costa Rica. These data are
bisected by the 5 September 2012 Mw 7.6 earthquake. The displacement time series contain multiple signals, including plate convergence, plate interface locking, coseismic and postseismic deformation, seasonal oscillations, SSEs, and noise.
GPS-measured coseismic and postseismic displacements associated with the Mw 7.6 earthquake are modeled and removed by a step function plus multiple timescale relaxation processes with four characteristic times: 11, 94, 470, and 1,865 days. Seasonal
oscillations are eliminated using a multichannel singular spectrum analysis (M-SSA). Ten major SSEs (Mw > 6.6) are observed in the remaining time series, with a constant recurrence interval of 21.7 ± 2.6 months. SSEs occur in both shallow (~10 km)
and deep (~35 km) portions of the plate interface, but the latter last longer and have larger magnitudes. There is minimum to no slow slip in theMw 7.6 seismic rupture area and a persistent slow slip patch beneath the Nicoya Gulf entrance. Despite
strong earthquake-related stress perturbations, the inter-SSE locking status on the megathrust is very similar between the late and early stages of the earthquake cycle and includes locked patches that ruptured in the 2012 earthquake or continue to
rupture via SSEs. Some locked patches offshore south of the Nicoya Peninsula did not rupture in 2012, do not participate in SSEs, and may be indicative of supercycle behavior, that is, strain accumulation over several seismic cycles. These areas
warrant heightened monitoring. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Slow-slip events are different ways than earthquakes to release energy stored in the earth's crust, but they do not cause damage. We are
building a database of slow slide events in Northwest Costa Rica from GPS measurements with millimeter accuracy. We found that these events occurred approximately every 22 months and the repeat time remained unchanged by the September 5, 2012 Mw 7.6
earthquake in Costa Rica. Modeling work that links ground-based GPS measurements to crustal movement suggests that the largest slow sliding movement is found below the entrance to the Gulf of Nicoya. The stress accumulation patterns before and after
September 5, 2012 Mw 7.6 are similar. |
| GEOSCAN ID | 327286 |
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