Postseismic deformation and body forces shaping the Apennines and adjacent sedimentary basins in Umbria-Marche

R. E. M. Riva, A. Aoudia


The geodynamic complexity of the Apennines and adjacent sedimentary basins in Umbria-Marche (North-Central
Italy) makes the dynamics of the present day deformation and its relationships with the seismicity less well understood.
In this paper, we argue that, further to buoyancy forces, postseismic deformation of earthquakes taking place
on the Apennines contributes to the regional deformation. We investigate the interaction between the normal faulting
system responsible of the 1997 Umbria-Marche earthquake sequence (Colfiorito fault) and the low angle normal
faulting system bordering the sedimentary basins, namely the Altotiberina fault. We set-up a 2D finite element
model of the lithosphere-asthenosphere accounting for lateral heterogeneities and investigate how this heterogeneous
structure is capable of localizing strain under the Umbria-Marche sedimentary basins, providing a way for
the Colfiorito fault to influence the evolution of the Altotiberina fault. We show how the two different length and
time scale processes, namely postseismic deformation and buoyancy, are complementary in shaping the Apennines
and adjacent sedimentary basins. The high resolution deformation patterns modeled in this study can hardly be reproduced
by a model accounting only for external forces such as a rotating or subducting or retreating Adria.


Viscoelastic relaxation;Aseismic slip;Body forces;Normal faults

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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X