Publication Date:
2021-01-05
Description:
We investigate fault interaction through elastic stress transfer among a sequence of
moderate-magnitude main shocks (5 〈 Mw 〈 6) which ruptured distinct normal fault
segments during a seismic sequence in the Umbria-Marche region (central Apennines).
We also model the spatial pattern of aftershocks and their faulting mechanisms through
Coulomb stress changes. We compute stress perturbations caused by earthquake
dislocations in a homogeneous half-space. Our modeling results show that seven out of
eight main shocks of the sequence occur in areas of enhanced Coulomb stress, implying
that elastic stress transfer may have promoted the occurrence of these moderate-
magnitude events. Our modeling results show that stress changes caused by normal
faulting events reactivated and inverted the slip of a secondary N-S trending strike-slip
fault inherited from compressional tectonics in its shallowest part (1–3 km). Of the
1517 available aftershocks, 82% are located in areas of positive stress changes for
optimally oriented planes (OOPs) for Coulomb failure. However, only 45% of the 322
available fault plane solutions computed from polarity data is consistent with
corresponding focal mechanisms associated with the OOPs. The comparison does not
improve if we compute the optimally oriented planes for Coulomb failure by fixing the
strike orientation of OOPs using information derived from structural geology. Our
interpretation of these modeling results is that elastic stress transfer alone cannot jointly
explain the aftershock spatial distribution and their focal mechanisms.
Description:
Published
Description:
B05S20
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
reserved
Keywords:
Coulomb Stress Changes
;
Normal Faulting
;
04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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