Notes on the co-seismic stress field evolution during the 1997 Umbria-Marche (Italy) aftershock sequence

Alberti, Mauro (2010) Notes on the co-seismic stress field evolution during the 1997 Umbria-Marche (Italy) aftershock sequence. Italian journal of geosciences, 129 (1). pp. 15-28. ISSN 2038-1727

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The Umbria-Marche 1997 seismic sequence occurred in a region of the Northern Apennines (Italy) that has been under extension since the Late Pliocene. This sequence activated normal faults and high-angle faults inherited from an earlier contractional tectonic phase. A one-month period starting immediately after the mainshocks is studied. During the initial ten days, the coseismic stress field shows evidence of permutations between the S1 and S2 axes, with the presence of a local strike-slip regime. Over the following 20 days, stress variations became more gradual. We suggest that permutations and rotations of the principal stress axes are due to mechanical anisotropies or rheological variations within the fault zones of inherited faults. The inverted normal and strike-slip stress regimes explain almost all the observed relationships between fault strike and fault slip direction, thus suggesting that fault slip is fundamentally controlled by the active stress field, with a secondary influence of kinematic factors such as strain compatibility due to fault slip interactions.

Item Type: Article
Additional Information: Abstract anche in italiano
Uncontrolled Keywords: Umbria-Marche 1997 seismic sequence, stress permutation, stress fields
Subjects: 500 Scienze naturali e Matematica > 550 Scienze della Terra > 551 Geologia, Idrologia, Meteorologia > 551.2 Vulcani, terremoti, acque termali e gas > 551.22 Terremoti (Classificare qui la Sismologia) (Classificare le onde di maremoto in 551.463)
Depositing User: Users 66 not found.
Date Deposited: 05 Jan 2012 17:03
Last Modified: 05 Jan 2012 17:03

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