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Role of poroelasticity during the early postseismic deformation of the 2010 Maule megathrust earthquake
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  • Carlos Peña,
  • Sabrina Metzger,
  • Oliver Heidbach,
  • Jonathan R Bedford,
  • Bodo Bookhagen,
  • Marcos Moreno,
  • Oncken Onno,
  • Fabrice Cotton
Carlos Peña
Helmholtz Centre Potsdam German Research Centre for Geosciences

Corresponding Author:[email protected]

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Sabrina Metzger
Helmholtz-Zentrum, Deutsches GeoForschungsZentrum Potsdam
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Oliver Heidbach
Helmholtz Centre Potsdam German Research Centre for Geosciences
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Jonathan R Bedford
Deutsches GeoForschungsZentrum
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Bodo Bookhagen
University of Potsdam
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Marcos Moreno
Universidad de Concepción
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Oncken Onno
GeoForschungsZentrum Potsdam
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Fabrice Cotton
GFZ
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Abstract

Megathrust earthquakes impose changes of differential stress and pore pressure in the lithosphere-asthenosphere system that are transiently relaxed during the postseismic period primarily due to afterslip, viscoelastic and poroelastic processes. Especially during the early postseismic phase, however, the relative contribution of these processes to the observed surface deformation is unclear. To investigate this, we use geodetic data collected in the first 48 days following the 2010 Maule earthquake and a poro-viscoelastic forward model combined with an afterslip inversion. This model approach fits the geodetic data 14% better than a pure elastic model. Particularly near the region of maximum coseismic slip, the predicted surface poroelastic uplift pattern explains well the observations. If poroelasticity is neglected, the spatial afterslip distribution is locally altered by up to ±40%. Moreover, we find that shallow crustal aftershocks mostly occur in regions of increased postseismic pore-pressure changes, indicating that both processes might be mechanically coupled