Is earthquake activity along the French Atlantic margin favoured by local rheological contrasts?
| Autor: | Bertrand Delouis, Nicole Béthoux, Yves Mazabraud |
|---|---|
| Přispěvatelé: | Université des Antilles et de la Guyane (UAG), Géoazur (GEOAZUR 7329), Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]) |
| Rok vydání: | 2013 |
| Předmět: |
Extensional deformation
Global and Planetary Change 010504 meteorology & atmospheric sciences Deformation (mechanics) [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Magnitude (mathematics) 010502 geochemistry & geophysics 01 natural sciences Stress field General Earth and Planetary Sciences Atlantic margin Shear zone Finite element code Geology Seismology 0105 earth and related environmental sciences Stress concentration |
| Zdroj: | Comptes Rendus Géoscience Comptes Rendus Géoscience, Elsevier, 2013, 345 (9-10), pp.373-382. ⟨10.1016/j.crte.2013.07.004⟩ Comptes Rendus Géoscience, Elsevier Masson, 2013, 345 (9-10), pp.373-382. ⟨10.1016/j.crte.2013.07.004⟩ |
| ISSN: | 1631-0713 |
| Popis: | The seismological study of recent seismic crises near Oleron Island confirms the coexistence of an extensional deformation and a transtensive regime in the Atlantic margin of France, which is different from the general western European stress field corresponding to a strike-slip regime. We argue that the switch of the principal stress axes σ 1 / σ 2 in a NW–SE vertical plane is linked with the existence of crustal heterogeneities. Events of magnitude larger than 5 sometimes occur along the Atlantic margin of France, such as the 7 September 1972 ( M L = 5.2) earthquake near Oleron island and the 30 September 2002 ( M L = 5.7) Hennebont event in Brittany. To test the mechanism of local strain localization, we model the deformation of the hypocentral area of the Hennebont earthquake using a 3D thermo-mechanical finite element code. We conclude that the occurrence of moderate earthquakes located in limited parts of the Hercynian shear zones (as the often reactivated swarms near Oleron) could be due to local reactivation of pre-existing faults. These sporadic seismic ruptures are favoured by stress concentration due to rheological heterogeneities. |
| Databáze: | OpenAIRE |
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