Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone
International audience Comparison of the eroded off-rift zone left inactive by plate motion with the inner active seismic rift zone allows us to constrain the fracturing mechanisms. In eastern off-rift zone, we measured 423 fault slips (including normal and strike-slip faults). Inversion of fault sl...
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ftunigrenoble:oai:HAL:hal-00815426v1 2024-05-12T08:06:03+00:00 Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone Plateaux, R. Bergerat, Françoise Béthoux, N. Villemin, Thierry Gerbault, M. Géoazur (GEOAZUR 6526) Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur Université Côte d'Azur (UniCA)-Université Côte d'Azur (UniCA)-Centre National de la Recherche Scientifique (CNRS) Institut des Sciences de la Terre de Paris (iSTeP) Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS) Environnements, Dynamiques et Territoires de Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) 2012-12-18 https://hal.science/hal-00815426 https://doi.org/10.1016/j.tecto.2012.01.013 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.tecto.2012.01.013 hal-00815426 https://hal.science/hal-00815426 doi:10.1016/j.tecto.2012.01.013 ISSN: 0040-1951 EISSN: 1879-3266 Tectonophysics https://hal.science/hal-00815426 Tectonophysics, 2012, 581, pp.19-34. ⟨10.1016/j.tecto.2012.01.013⟩ [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2012 ftunigrenoble https://doi.org/10.1016/j.tecto.2012.01.013 2024-04-18T02:16:37Z International audience Comparison of the eroded off-rift zone left inactive by plate motion with the inner active seismic rift zone allows us to constrain the fracturing mechanisms. In eastern off-rift zone, we measured 423 fault slips (including normal and strike-slip faults). Inversion of fault slip data reveals the parallelism of the minimum stress (σ3) computed for the normal and for the strike-slip faulting, and consistency with the direction of plate divergence. North of the Vatnajökull, in the active rift zone, we analysed 14,250 earthquakes recorded by the Icelandic Meteorological Office (IMO) between 2004 and 2009, especially northeast of the Askja volcano. Two main average focal depths were determined at 5 km (Herðubreið table mountain) and 15 km (Upptyppingar hyaloclastite ridge). The double couple focal mechanisms determined by IMO revealed that more than half of the mechanisms are strike-slip. Faulting type both in active and off-rift zone reveals an unusual importance of strike-slip regime in such an extensional tectonic context. This can be explained by stress permutations (σ1/σ2). Similarities in terms of stress orientations and type of faulting are observed both in the old and present-day rift zones. We assume that the seismic events may be generated by rapid deep magma intrusion, also associated with shallower hydrothermal activities. We thus propose that the presence of fluids, shear failure (double couple focal mechanism) and stress permutations in both active and off-rift zones are closely linked. Assuming a Drucker-Prager failure criterion, we evaluated analytically that a state near of lithostatic pore pressure is a necessary condition for shear failure at shallow (5 km) and deep (15 km) depth, in a simple context of crustal extension that allows for stress permutations. However, processes favouring stress permutations cannot be further constrained from our observations since the dynamics of fluid, materiel heterogeneity and post-glacial rebound can also play a significant role Article in Journal/Newspaper Iceland Vatnajökull Université Grenoble Alpes: HAL Askja ENVELOPE(-16.802,-16.802,65.042,65.042) Table Mountain ENVELOPE(69.031,69.031,-48.668,-48.668) Upptyppingar ENVELOPE(-16.245,-16.245,65.038,65.038) Vatnajökull ENVELOPE(-16.823,-16.823,64.420,64.420) Tectonophysics 581 19 34 |
institution |
Open Polar |
collection |
Université Grenoble Alpes: HAL |
op_collection_id |
ftunigrenoble |
language |
English |
topic |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences Plateaux, R. Bergerat, Françoise Béthoux, N. Villemin, Thierry Gerbault, M. Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone |
topic_facet |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience Comparison of the eroded off-rift zone left inactive by plate motion with the inner active seismic rift zone allows us to constrain the fracturing mechanisms. In eastern off-rift zone, we measured 423 fault slips (including normal and strike-slip faults). Inversion of fault slip data reveals the parallelism of the minimum stress (σ3) computed for the normal and for the strike-slip faulting, and consistency with the direction of plate divergence. North of the Vatnajökull, in the active rift zone, we analysed 14,250 earthquakes recorded by the Icelandic Meteorological Office (IMO) between 2004 and 2009, especially northeast of the Askja volcano. Two main average focal depths were determined at 5 km (Herðubreið table mountain) and 15 km (Upptyppingar hyaloclastite ridge). The double couple focal mechanisms determined by IMO revealed that more than half of the mechanisms are strike-slip. Faulting type both in active and off-rift zone reveals an unusual importance of strike-slip regime in such an extensional tectonic context. This can be explained by stress permutations (σ1/σ2). Similarities in terms of stress orientations and type of faulting are observed both in the old and present-day rift zones. We assume that the seismic events may be generated by rapid deep magma intrusion, also associated with shallower hydrothermal activities. We thus propose that the presence of fluids, shear failure (double couple focal mechanism) and stress permutations in both active and off-rift zones are closely linked. Assuming a Drucker-Prager failure criterion, we evaluated analytically that a state near of lithostatic pore pressure is a necessary condition for shear failure at shallow (5 km) and deep (15 km) depth, in a simple context of crustal extension that allows for stress permutations. However, processes favouring stress permutations cannot be further constrained from our observations since the dynamics of fluid, materiel heterogeneity and post-glacial rebound can also play a significant role |
author2 |
Géoazur (GEOAZUR 6526) Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur Université Côte d'Azur (UniCA)-Université Côte d'Azur (UniCA)-Centre National de la Recherche Scientifique (CNRS) Institut des Sciences de la Terre de Paris (iSTeP) Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS) Environnements, Dynamiques et Territoires de Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Plateaux, R. Bergerat, Françoise Béthoux, N. Villemin, Thierry Gerbault, M. |
author_facet |
Plateaux, R. Bergerat, Françoise Béthoux, N. Villemin, Thierry Gerbault, M. |
author_sort |
Plateaux, R. |
title |
Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone |
title_short |
Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone |
title_full |
Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone |
title_fullStr |
Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone |
title_full_unstemmed |
Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone |
title_sort |
implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east iceland rift zone |
publisher |
HAL CCSD |
publishDate |
2012 |
url |
https://hal.science/hal-00815426 https://doi.org/10.1016/j.tecto.2012.01.013 |
long_lat |
ENVELOPE(-16.802,-16.802,65.042,65.042) ENVELOPE(69.031,69.031,-48.668,-48.668) ENVELOPE(-16.245,-16.245,65.038,65.038) ENVELOPE(-16.823,-16.823,64.420,64.420) |
geographic |
Askja Table Mountain Upptyppingar Vatnajökull |
geographic_facet |
Askja Table Mountain Upptyppingar Vatnajökull |
genre |
Iceland Vatnajökull |
genre_facet |
Iceland Vatnajökull |
op_source |
ISSN: 0040-1951 EISSN: 1879-3266 Tectonophysics https://hal.science/hal-00815426 Tectonophysics, 2012, 581, pp.19-34. ⟨10.1016/j.tecto.2012.01.013⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.tecto.2012.01.013 hal-00815426 https://hal.science/hal-00815426 doi:10.1016/j.tecto.2012.01.013 |
op_doi |
https://doi.org/10.1016/j.tecto.2012.01.013 |
container_title |
Tectonophysics |
container_volume |
581 |
container_start_page |
19 |
op_container_end_page |
34 |
_version_ |
1798848476750020608 |