Role of poroelasticity during the early postseismic deformation of the
2010 Maule megathrust earthquake
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