EGU23-7301
https://doi.org/10.5194/egusphere-egu23-7301
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Is the Pampean flat-slab responsible for the differences in post-seismic motions between Maule and Illapel earthquakes?

Emilie Klein1, Hugo Boulze1, Christophe Vigny1, Luce Fleitout1, and Jean-Didier Garaud2
Emilie Klein et al.
  • 1Laboratoire de Géologie, CNRS - Ecole normale supérieure - PSL University, Paris, France (boulze@geologie.ens.fr)
  • 2ONERA - The French Aerospace Lab, F-92322 Châtillon, France

Ever since the Maule earthquake (Mw8.8, 2010), a quick vertical uplift is measured thanks to GNSS in the Andes, facing the rupture zone (~250 km to the trench). Models built for the Maule earthquake [Klein et al. 2016] have highlighted that a low-viscosity channel is required to explain the post-seismic uplift. This channel is located along the slab between 50 km and 130 km depth and has a viscosity of a few 1017 Pa.s - lower than in the asthenosphere, 1018 Pa.s. 

After the Illapel earthquake (Mw8.3, 2015), simple observations on GNSS time-series show that no uplift occurred in the Andes at an equivalent distance to the trench than in the case of the Maule earthquake. The subduction in the Illapel region is characterized by a flat-slab (called the Pampean flat-slab) in contrast with the normal-dipping subduction in the region of Maule.

Here, we investigate what is the impact of the Pampean flat-slab on the post-seismic deformations of the Illapel earthquake. In particular, we try to understand  whether the presence of the flat-slab inhibits the effect of the low-viscosity channel. For that purpose we compare GNSS vertical displacements with predictions in both regions of Maule and Illapel from a 3D spherical finite-element model that accounts for the slab geometry of the Chilean subduction zone.

How to cite: Klein, E., Boulze, H., Vigny, C., Fleitout, L., and Garaud, J.-D.: Is the Pampean flat-slab responsible for the differences in post-seismic motions between Maule and Illapel earthquakes?, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-7301, https://doi.org/10.5194/egusphere-egu23-7301, 2023.