Mon Aug 24, F. Flechtner
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Parla, Rajesh, Panet, Isabelle, Gharti, Hom Nath, Martin, Roland, Remy, Dominique, and Plazolles, Bastien, 2026. 3D numerical modelling of gravity perturbations due to short–term slab deformations at the Japan subduction zone. Geophysical Journal International, .
• from the NASA Astrophysics Data System • by the DOI System •
@ARTICLE{2026GeoJI.tmp..568P,
author = {{Parla}, Rajesh and {Panet}, Isabelle and {Gharti}, Hom Nath and {Martin}, Roland and {Remy}, Dominique and {Plazolles}, Bastien},
title = "{3D numerical modelling of gravity perturbations due to short-term slab deformations at the Japan subduction zone}",
journal = {Geophysical Journal International},
year = 2026,
month = jul,
abstract = "{Anomalous medium-scale gravity gradient changes reported prior to the
2011 9.0 Tohoku and the 2010 8.8 Maule earthquakes have been
attributed to transient extensional deformations of the
subducting slabs at depths of
\raisebox{-0.5ex}\textasciitilde150-300 km. With a regional-
scale extent and weak associated surface displacements, these
signals and their deformation sources are not well understood.
Our aim here is to improve their modelling by taking into
account the 3D elastic structure of the subduction zone, and by
assessing how the surface observables respond to variations in
the spatial distribution and the depth of the deformation
source. Taking the case of the pre-Tohoku signals, and
representing slab extension with ensembles of dislocations, we
investigate the corresponding gravitational and surface
displacement signals using fully three-dimensional spectral-
infinite-element simulations implemented in the numerical code
SPECFEM-X, incorporating a realistic subduction-zone geometry.
For the considered deep deformations, our results show a limited
impact of the lateral elastic structure on the surface
displacement and geoid signals, which differ by less than
\raisebox{-0.5ex}\textasciitilde2\% and
\raisebox{-0.5ex}\textasciitilde3\% respectively from the purely
radially layered case. The degree of the spatial distribution of
the deformation and the depth more strongly impact the relative
amplitudes and the smoothness of the gravity and surface
displacement signals. Broadly distributed slab deformation leads
to a reduction in the extremum amplitude of the vertical surface
displacements by up to \raisebox{-0.5ex}\textasciitilde40\%
compared to the results obtained for highly localized slab
deformation of similar magnitude, whereas the amplitude of the
medium-scale gravity gradient signals decreases by
{\ensuremath{\leq}}20\% only. These surface displacement and
gravity gradient signals are attenuated by
\raisebox{-0.5ex}\textasciitilde90\% and
\raisebox{-0.5ex}\textasciitilde60\%, respectively, when moving
the source depth from 100 to 500 km. In all cases, broader-scale
gravity gradient signals are obtained. Thus, while distributed
deformations contribute to smoothing the gravity signals and
reducing the amplitude of the corresponding surface
displacements, they still do not account for the required sub-
centimetric level of ground motions. Our results finally provide
a quantitative framework for interpreting intermediate-scale
GRACE pre-seismic anomalies at subduction zones.}",
doi = {10.1093/gji/ggag293},
adsurl = {https://ui.adsabs.harvard.edu/abs/2026GeoJI.tmp..568P},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
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