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51. Comments on the paper 'Two independent real-time precursors of the 7.8 M earthquake in Ecuador based on radioactive and geodetic processes – Powerful tools for an early warning system' by Toulkeridis et al. (2019)

Author

Yepes, H., Nocquet, Jean-Mathieu, Bernard, B., Palacios, P. B., Vaca, S., and Aguaiza, S.

Subjects
Early warning, bepress|Physical Sciences and Mathematics, Radiation, bepress|Physical Sciences and Mathematics|Earth Sciences|Geophysics and Seismology, GPS, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Geophysics and Seismology, bepress|Physical Sciences and Mathematics|Earth Sciences, Forecast, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, Earthquake precursor, EarthArXiv|Physical Sciences and Mathematics
Abstract

In the paper entitled "Two independent real-time precursors of the 7.8 M earthquake in Ecuador based on radioactive and geodetic processes - Powerful tools for an early warning system", Toulkeridis et al. (2019) claim that they found radiation and GPS signal anomalies before the April 16th 2016 Pedernales earthquake (Ecuador) and that their findings can be used to forecast earthquakes in the medium and short term in active continental margins. Using an extended data set that overlaps Toulkeridis et al. (2019) study period, we find: (1) the success rate of predicting earthquakes using radiation anomalies is 2.5 %; (2) radiation anomalies, including the one recorded during the hours before the M 7.8 earthquake, temporally correlate with local rainfall; (3) Toulkeridis et al. (2019) GPS results are physically unrealistic and inconsistent with previously published GPS and InSAR analysis; (4) there is no anomaly in the GPS time series before the earthquake. Therefore, Toulkeridis et al. (2019) results are not reliable evidence of precursors to the M 7.8 earthquake in 2016 in Ecuador, and their proposed method cannot be used to forecast earthquakes.

Published
2019

52. Ridge Subduction and Afterslip Control Aftershock Distribution of the 2016 Mw 7.8 Ecuador Earthquake

Author

Rolandone, Frederique, Hernandez, María, Nocquet, Jean-Mathieu, Hernandez, Stephen, Hoskins, Mariah, Soto-Cordero, Lillian, Charvis, Philippe, Alvarado, Alexandra, Michaud, François, León-Ríos, Sergio, Paulatto, Michele, Lynner, Colton, Régnier, Marc, Agurto-Detzel, Hans, Ruiz, Mario, Mercerat, Diego, Beck, Susan, Rietbrock, Andreas, Meltzer, Anne, Font, Yvonne, and Ambrois, David

Subjects
bepress|Physical Sciences and Mathematics, bepress|Physical Sciences and Mathematics|Earth Sciences|Geophysics and Seismology, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Geophysics and Seismology, bepress|Physical Sciences and Mathematics|Earth Sciences, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, EarthArXiv|Physical Sciences and Mathematics
Abstract

We characterise the aftershock sequence following the 2016 Mw=7.8 Pedernales earthquake. More than 10,000 events were detected and located, with magnitudes up to 6.9. Most of the aftershock seismicity results from interplate thrust faulting, but we also observe a few normal and strike-slip mechanisms. Seismicity extends for more than 300 km along strike, and is constrained between the trench and the maximum depth of the coseismic rupture. The most striking feature is the presence of three seismicity bands, perpendicular to the trench, which are also observed during the interseismic period. Additionally, we observe a linear dependency between the temporal evolution of afterslip and aftershocks. We also find a temporal semi-logarithmic expansion of aftershock seismicity along strike and dip directions, further indicating that their occurrence is modulated by afterslip. Lastly, we observe that the spatial distribution of seismic and aseismic slip processes is correlated to the distribution of bathymetric anomalies associated with the northern flank of the Carnegie Ridge, suggesting that slip in the area could be influenced by the relief of the subducting seafloor. To explain our observations, we propose a conceptual model in which the Ecuadorian margin is subject to a bimodal slip mode, with distributed seismic and aseismic slip mechanically controlled by the subduction of a rough oceanic relief. Our study sheds new light on the mechanics of subduction, relevant for convergent margins with a complex and heterogeneous structure such as the Ecuadorian margin.

Published
2019

53. Lower crustal heterogeneity beneath the Northern Tibetan Plateau constrained by GPS measurements following the 2001 Mw7.8 Kokoxili earthquake

Author

Liu, S. Z., Xu, X. W., Klinger, Y., Nocquet, Jean-Mathieu, Chen, G. H., Yu, G. H., and Jonsson, S.

Abstract

We use GPS measurements across the Xidatan segment of the Kunlun fault in the Tibetan Plateau to investigate the surface deformation following the 2001 Mw 7.8 Kokoxili earthquake. We find significant postseismic deformation during the period 2007-2015, characterized by an asymmetric shear across the 2001 rupture, with average velocities reaching similar to 10 mm/year about 30-45 km south of the coseismic rupture. We also find that the postseismic transients diffused away from the coseismic rupture through time, with a shift of the maximum transient rates from similar to 20-30 km south of the rupture in 2001-2002 to similar to 30-45 km in 2007-2015. Viscoelastic relaxation is the dominant physical process during the period 2007-2015. The estimated effective viscosity of the lower crust beneath the Songpan-Ganzi terrane is 2 x 10(18)-3 x 10(18) Pa s from the 2001-2002 data, and it has increased to similar to 2 x 10(19) Pa s for the period 6 to 14 years after the event. The large asymmetry in the postseismic deformation field indicates a laterally heterogeneous lower crust beneath the northern Tibetan Plateau. Viscoelastic relaxation models show that the viscosity of the lower crust beneath the Qaidam basin is similar to 2 and similar to 4 times larger than the viscosity of the lower crust beneath the Songpan-Ganzi terrane in 2001-2002 and 2007-2015, respectively. Based on these data and results from previous studies, we postulate that the Kunlun fault itself is not the unique rheological boundary and that additional domains with viscosity increasing from the Qiangtang terrane to the Qaidam basin appear to be required. Plain Language Summary Viscoelastic relaxation of earthquake-induced deviatoric stress change can last for several decades. In 2001, the Mw7.8 Kokoxili earthquake occurred along the Kunlun fault in the northern Tibetan Plateau. GPS measurements in the first two decades after the 2001 event show (1) that postseismic transients diffused away from the fault and (2) that postseismic transients are asymmetric across the coseismic rupture. We find that lower crustal viscosity heterogeneity leads to the observed asymmetric deformation. Although geodetic data constraints with better spatial and temporal coverage are needed, we find that lower crustal viscosity may exhibit northward stepwise increase across the Jinsha River suture, Kunlun fault, and the southern margin of the Qaidam basin. Our findings provide new constraints on the lithospheric structure and tectonic deformation in the northern Tibetan Plateau.

Published
2019

54. Areas prone to slow slip events impede earthquake rupture propagation and promote afterslip

Author

Rolandone, Frédérique, Nocquet, Jean-Mathieu, Mothes, Patricia, Jarrin, Paul, Vallée, Martin, Cubas, Nadaya, Hernandez, Stephen, Plain, Morgan, Vaca, Sandro, Font, Yvonne, Déformations, sismotectonique, imagerie, relief (DéSIR), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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), 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, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Instituto Geofísico, Escuela Politécnica Nacional (EPN), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géosciences Marines (LGM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Escuala Politec Nacl, Institut Geofis, Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, and Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract

International audience; At subduction zones, transient aseismic slip occurs either as afterslip following a large earthquake or as episodic slow slip events during the interseismic period. Afterslip and slow slip events are usually considered as distinct processes occurring on separate fault areas governed by different frictional properties. Continuous GPS (Global Positioning System) measurements following the 2016 Mw (moment magnitude) 7.8 Ecuador earthquake reveal that large and rapid afterslip developed at discrete areas of the megathrust that had previously hosted slow slip events. Regardless of whether they were locked or not before the earthquake, these areas appear to persistently release stress by aseismic slip throughout the earthquake cycle and outline the seismic rupture, an observation potentially leading to a better anticipation of future large earthquakes

Published
2018

55. Monitoring the earthquake cycle in the Northern Andes from the Ecuadorian cGPS network

Author

Mothes, P. A., Rolandone, Frédérique, Nocquet, Jean-Mathieu, Jarrin, P. A., Alvarado, A. P., Ruiz, M. C., Cisneros, D., Paez, H. M., and Segovia, M.

Abstract

The continuous Global Positioning System (cGPS) network operating in the northern Andes (Ecuador and Colombia) for about a decade has the main objectives of quantifying interseismic coupling along the subduction interface, detecting occurrence of transient aseismic episodic slip, detailing the rupture kinematics of large earthquakes, recording long-term movements along crustal faults, as well as recording swelling or deflation on the flanks of volcanoes. An opportunity to test the network's timely registry of surface coseismic offsets was provided by the 16 April 2016 M-w 7.8 Pedernales, Ecuador, earthquake whose epicenter was along the western margin of central Ecuador, South America. This large earthquake was the biggest to occur in the northern Andes since 1979 and produced static surface offsets that were recorded by the cGPS stations operating at distances out to similar to 400 km from source. Near-field stations, operating along the Ecuadorian littoral recorded static horizontal surface displacements up to 80 cm and high-rate GPS (HRGPS) stations recorded dynamic peak-to-peak displacements reaching 2 m. These measurements, together with seismic data, revealed the southward propagation of the seismic rupture, its spatial extent, and the successive breaking of two main asperities (Nocquet et al, 2017). Here, we provide the complete data set of static coseismic displacements recorded from Ecuador to southern Colombia out to 400 km from the rupture. North of the Pedernales earthquake's foci, in the adjoining Esmeraldas-Narino segment, some patches show high interseismic coupling and rapid strain accumulation is ongoing. In the 200-km-long Esmeraldas-Narino segment, the seismic potential is particularly high. cGPS data suggest that the Esmeraldas-Narino segment is likely a zone of future rupture.

Published
2018

56. Does Long-Term GPS in the Western Alps Finally Confirm Earthquake Mechanisms?

Author

Walpersdorf, A., Pinget, L., Vernant, P., Sue, C., Deprez, A., Baize, Stéphane, Bascou, Pascale, Baudin, Sandrine, Bock, Olivier, Briole, Pierre, Cali, José, Cardagliaguet, Jean-Paul, Champollion, cédric, Charade, Olivier, Chéry, Jean, Cotte, Nathalie, Dauteuil, Olivier, Doerflinger, Eric, Duquesnoy, Thierry, Durand, Stéphane, Fages, Romain, Ferhat, Gilbert, Flouzat, Mireille, Garayt, Bruno, Gay, Michel, Gravelle, Médéric, Guichard, Mikaël, Hinderer, Jacques, Jouanne, François, Lallemand, Charly, Masson, Frédéric, Mathis, Elise-Rachel, Mazzotti, Stéphane, Menut, Jean-Luc, Moreau, Frédérique, Morel, Laurent, Nicolas, Joelle, Nocquet, Jean-Mathieu, Ott, Laurent, Perosanz, Félix, Person, Thierry, Poirier, Etienne, Rigo, Alexis, Rolland, Lucie, Santamaria-Gomez, Alvaro, Saur, Sébastien, Scotti, Oona, Socquet, Anne, Ulrich, Patrice, Van Baelen, Joël, Vergnolle, Mathilde, Vidal, Maurin, Vigny, Christophe, Villemin, Thierry, Wöppelmann, Guy, Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire Dynamique de la Lithosphère (LDL), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Montpellier 2 - Sciences et Techniques (UM2), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), LAboratoire de REcherche en Géodésie [Paris] (LAREG), Laboratoire des Sciences et Technologies de l'Information Géographique (LaSTIG), École nationale des sciences géographiques (ENSG), Institut National de l'Information Géographique et Forestière [IGN] (IGN)-Institut National de l'Information Géographique et Forestière [IGN] (IGN)-École nationale des sciences géographiques (ENSG), Institut National de l'Information Géographique et Forestière [IGN] (IGN)-Institut National de l'Information Géographique et Forestière [IGN] (IGN), École normale supérieure - Paris (ENS Paris), École supérieure des géomètres et topographes (ESGT-CNAM), Conservatoire National des Arts et Métiers [CNAM] (CNAM), Centre National d'Études Spatiales [Toulouse] (CNES), Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Institut National de l'Information Géographique et Forestière [IGN] (IGN), Ecole et Observatoire des Sciences de la Terre (EOST), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Détection et de Géophysique (CEA) (LDG), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), GIPSA-Services (GIPSA-Services), Grenoble Images Parole Signal Automatique (GIPSA-lab), Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), SIGMAPHY (GIPSA-SIGMAPHY), Département Images et Signal (GIPSA-DIS), Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Grenoble Images Parole Signal Automatique (GIPSA-lab), Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Pierre Mendès France - Grenoble 2 (UPMF)-Université Stendhal - Grenoble 3-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-GIPSA Pôle Sciences des Données (GIPSA-PSD), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 7329), 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)-Université Côte d'Azur (UCA), Géosciences Environnement Toulouse (GET), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire de Météorologie Physique - Clermont Auvergne (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Paris sciences et lettres (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Grenoble Images Parole Signal Automatique (GIPSA-lab ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), GIPSA - Signal Images Physique (GIPSA-SIGMAPHY), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Grenoble Images Parole Signal Automatique (GIPSA-lab ), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Horizon 2020 Framework ProgrammeANR-11-EQPX-0040, Agence Nationale de la RechercheANR10LABX56, LabEx OSUG@2020, ANR-11-EQPX-0040,RESIF-CORE,Réseau sismologique et géodésique français : l'équipement fondamental(2011), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Laboratoire Chrono-environnement (UMR 6249) (LCE), École normale supérieure - Paris (ENS-PSL), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Environnements, Dynamiques et Territoires de Montagne (EDYTEM)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract

International audience; The availability of GPS survey data spanning 22 years, along with several independent velocity solutions including up to 16 years of permanent GPS data, presents a unique opportunity to search for persistent (and thus reliable) deformation patterns in the Western Alps, which in turn allow a reinterpretation of the active tectonics of this region. While GPS velocities are still too uncertain to be interpreted on an individual basis, the analysis of range-perpendicular GPS velocity profiles clearly highlights zones of extension in the center of the belt (15.3 to 3.1 nanostrain/year from north to south), with shortening in the forelands. The contrasting geodetic deformation pattern is coherent with earthquake focal mechanisms and related strain/stress patterns over the entire Western Alps. The GPS results finally provide a reliable and robust quantification of the regional strain rates. The observed vertical motions of 2.0 to 0.5 mm/year of uplift from north to south in the core of the Western Alps is interpreted to result from buoyancy forces related to postglacial rebound, erosional unloading, and/or viscosity anomalies in the crustal and lithospheric root. Spatial decorrelation between vertical and horizontal (seismicity related) deformation calls for a combination of processes to explain the complex present-day dynamics of the Western Alps.

Published
2018

57. Stochastic static fault slip inversion from geodetic data with non-negativity and bound constraints

Author

Nocquet, Jean-Mathieu

Subjects
Earthquake source observation, Inverse theory, Satellite Geodesy
Abstract

Despite surface displacements observed by geodesy are linear combinations of slip at faults in an elastic medium, determining the spatial distribution of fault slip remains a ill-posed inverse problem. A widely used approach to circumvent the illness of the inversion is to add regularization constraints in terms of smoothing and/or damping so that the linear system becomes invertible. However, the choice of regularization parameters is often arbitrary, and sometimes leads to significantly different results. Furthermore, the resolution analysis is usually empirical and cannot be made independently of the regularization. The stochastic approach of inverse problems provides a rigorous framework where the a priori information about the searched parameters is combined with the observations in order to derive posterior probabilities of the unkown parameters. Here, I investigate an approach where the prior probability density function (pdf) is a multivariate Gaussian function, with single truncation to impose positivity of slip or double truncation to impose positivity and upper bounds on slip for interseismic modelling. I show that the joint posterior pdf is similar to the linear untruncated Gaussian case and can be expressed as a truncated multivariate normal (TMVN) distribution. The TMVN form can then be used to obtain semi-analytical formulae for the single, 2-D or n-D marginal pdf. The semi-analytical formula involves the product of a Gaussian by an integral term that can be evaluated using recent developments in TMVN probabilities calculations. Posterior mean and covariance can also be efficiently derived. I show that the maximum posterior (MAP) can be obtained using a non-negative least-squares algorithm for the single truncated case or using the bounded-variable least-squares algorithm for the double truncated case. I show that the case of independent uniform priors can be approximated using TMVN. The numerical equivalence to Bayesian inversions using Monte Carlo Markov chain (MCMC) sampling is shown for a synthetic example and a real case for interseismic modelling in Central Peru. The TMVN method overcomes several limitations of the Bayesian approach using MCMC sampling. First, the need of computer power is largely reduced. Second, unlike Bayesian MCMC-based approach, marginal pdf, mean, variance or covariance are obtained independently one from each other. Third, the probability and cumulative density functions can be obtained with any density of points. Finally, determining the MAP is extremely fast.

Published
2018

61. Variable Slip Modes in Postseismic Deformation North of the April 16, 2016 Mw 7.8 Pedernales, Ecuador Megathrust Earthquake

Author

Hoskins, Mariah Chambers, primary, Meltzer, Anne, additional, Soto-Cordero, Lillian, additional, Stachnik, Josh, additional, Beck, Susan L., additional, Lynner, Colton, additional, Ruiz, Mario Calizto, additional, Alvarado, Alexandra Patricia, additional, Hernandez, Stephen, additional, Charvis, Philippe, additional, Font, Yvonne, additional, Nocquet, Jean-Mathieu, additional, Rolandone, Frederique, additional, Regnier, Marc M, additional, Agurto-Detzel, Hans, additional, Rios, Sergio Leon, additional, and Rietbrock, Andreas, additional

Published
2019
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62. Repeating Earthquakes at the Edge of the Afterslip of the 2016 Ecuadorian MW 7.8 Pedernales Earthquake.

Author

Chalumeau, Caroline, Agurto‐Detzel, Hans, De Barros, Louis, Charvis, Philippe, Galve, Audrey, Rietbrock, Andreas, Alvarado, Alexandra, Hernandez, Stephen, Beck, Susan, Font, Yvonne, Hoskins, Mariah C., León‐Ríos, Sergio, Meltzer, Anne, Lynner, Colton, Rolandone, Frederique, Nocquet, Jean‐Mathieu, Régnier, Marc, Ruiz, Mario, Soto‐Cordero, Lillian, and Vaca, Sandro

Subjects
EARTHQUAKE aftershocks, AFTERSLIP, SUBDUCTION, GLOBAL Positioning System, PLATE tectonics
Abstract

Repeating earthquakes repeatedly rupture the same seismic asperity and are strongly linked to aseismic slip. Here, we study the repeating aftershocks of the April 16, 2016 MW 7.8 Pedernales earthquake in Ecuador, which generated a large amount of afterslip. Using temporary and permanent stations, we correlate waveforms from a one‐year catalog of aftershocks. We sort events with a minimum correlation coefficient of 0.95 into preliminary families, which are then expanded using template‐matching to include events from April 2015 to June 2017. In total, 376 repeaters are classified into 62 families of 4–15 events. They are relocated, first using manual picks, and then using a double difference method. We find repeating earthquakes during the whole period, occurring primarily within large aftershock clusters on the edges of the areas of largest afterslip release. Their recurrence times, shortened by the mainshock, subsequently increase following an Omori‐type law, providing a timeframe for the afterslip's deceleration. Although they are linked temporally to the afterslip, repeater‐derived estimates of slip differ significantly from GPS‐based models. Combined with the fact that repeaters appear more spatially correlated with the afterslip gradient than with the afterslip maxima, we suggest that stress accumulation at the edge of the afterslip may guide repeater behavior. Plain Language Summary: Ecuador, where the oceanic Nazca plate sinks under South America, is home to many earthquakes, like the 16th of April 2016 event that occurred near the city of Pedernales. This event generated smaller earthquakes (aftershocks), and slow, nondestructive slip (afterslip). Some aftershocks were repeating earthquakes, which are earthquakes that happen in the same spot multiple times. This type of event is usually caused by slow slip happening around it. Within a large slowly slipping area, stress will accumulate at locked, unmoving spots called asperities, that then break intermittently, causing repeating earthquakes. This means that by studying repeating earthquakes, we can measure the slow slip happening around them. In our study, we look for repeaters during the year before and after the Pedernales earthquake. We find repeaters primarily in large earthquake groups at the edge of the areas where afterslip happened. However, the measures of slow slip we calculated using repeaters and the estimates we calculated with GPS do not match. This, and the location of the repeaters around the slow slip areas rather than inside them, means that the repeaters might not be directly related to the slip amount, but to the stress accumulation at the edge of the slow‐slip area. Key Points: Repeating earthquakes are found in Ecuador in the aftermath of the MW 7.8 2016 Pedernales earthquakeRepeaters occur primarily in large clusters at the edges of the afterslip patches, where afterslip gradient is highRepeaters may respond to stress accumulation at the edge of the afterslip [ABSTRACT FROM AUTHOR]

Published
2021
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63. Contributors

Author

Aðalgeirsdóttir, Guðfinna, Albino, Fabien, Aoki, Yosuke, Awange, Joseph, Bürgmann, Roland, Chanard, Kristel, Chew, Clara, Crowell, Brendan W., Drouin, Vincent, Fu, Yuning, Geirsson, Halldór, Geng, Jianghui, Haas, Rüdiger, Heki, Kosuke, Hooper, Andy, Hreinsdóttir, Sigrún, Jiang, Weiping, Kraaijpoel, Dirk, Kreemer, Corné, Kutterer, Hansjörg, Li, Siqi, Liu, Lin, Maclennan, John, Magnússon, Eyjólfur, Mayer, Michael, Nocquet, Jean-Mathieu, Ófeigsson, Benedikt G., Pálsson, Finnur, Parks, Michelle, Rollins, Chris, Ruf, Chris, Sæmundsson, Þorsteinn, Schmidt, Peter, Schuh, Harald, Sigmundsson, Freysteinn, Sturkell, Erik, Trasatti, Elisa, Vallée, Martin, van Dam, Tonie, Wallace, Laura M., Whitehouse, Pippa, Yuan, Peng, Zaliapin, Ilya, and Zhang, Mingyuan

Published
2024
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64. Subducted oceanic relief locks the shallow megathrust in central Ecuador

Author

Collot, Jean-Yves, Sanclemente, Eddy, Nocquet, Jean-Mathieu, Leprêtre, Angélique, Ribodetti, Alessandra, Jarrin, Paul, Chlieh, Mohamed, Graindorge, David, Charvis, Philippe, Escuela Superior Politécnica del Litoral. Guayaquil, Escuela Superior Politécnica del Litoral [Guayaquil] (ESPOL), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Instituto Geofísico, Escuela Politécnica Nacional (EPN), 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), and Centre National de la Recherche Scientifique (CNRS)-Institut d'écologie et environnement-Observatoire des Sciences de l'Univers-Université de Brest (UBO)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
megathrust earthquake, seismic imaging, interseismic coupling, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, seamount subduction, slow slip event
Abstract

Whether subducted oceanic reliefs such as seamounts promote seismic rupture or aseismic slip remains controversial. Here we use swath bathymetry, prestack depth-migrated multichannel seismic reflection lines, and wide-angle seismic data collected across the central Ecuador subduction segment to reveal a broad similar to 55kmx50km, similar to 1.5-2.0km high, low height-to-width ratio, multipeaked, sediment-bare, shallow subducted oceanic relief. Owing to La Plata Island and the coastline being located, respectively, similar to 35km and similar to 50-60km from the trench, GPS measurements allow us to demonstrate that the subducted oceanic relief spatially correlates to a shallow, similar to 80kmx55km locked interplate asperity within a dominantly creeping subduction segment. The oceanic relief geometrical anomaly together with its highly jagged topography, the absence of a subduction channel, and a stiff erosive oceanic margin are found to be long-term geological characteristics associated with the shallow locking of the megathrust. Although the size and level of locking observed at the subducted relief scale could produce an M-w >7+ event, no large earthquakes are known to have happened for several centuries. On the contrary, frequent slow slip events have been recorded since 2010 within the locked patch, and regular seismic swarms have occurred in this area during the last 40years. These transient processes, together with the rough subducted oceanic topography, suggest that interplate friction might actually be heterogeneous within the locked patch. Additionally, we find that the subducted relief undergoes internal shearing and produces a permanent flexural bulge of the margin, which uplifted La Plata Island. Plain Language Summary Subducted seamounts play an important but still uncertain role in earthquake rupture processes, as seamounts are considered to subduct either aseismically or seismically. We use marine geophysical data across the central Ecuador convergent margin to reveal a broad similar to 55kmx50km, similar to 1.5-2.0km high, shallow subducted oceanic relief of the Carnegie Ridge. New GPS measurements collected on La Plata Island and along the Ecuador coast allow us to demonstrate that the subducted oceanic relief spatially correlates to a shallow, similar to 80kmx55km locked interplate asperity within a dominantly creeping subduction segment. The oceanic relief geometrical anomaly together with its rough topography and the stiff oceanic Ecuador margin are found to be long-term geological characteristics associated with the shallow locking of the plate interface. Although the size and level of locking observed at the subducted relief scale could produce an M-w >7+ event, no large earthquake but frequent slow slip events and associated seismic swarms occurred within the locked patch. These transient processes together with the rough subducted oceanic topography support the view of a heterogeneous interplate frictional pattern within the locked patch. On a regional scale, the subduction of the oceanic relief has deformed the Ecuador margin and uplifted La Plata Island.

Published
2017

65. Elastic block and strain modeling of GPS data around the Haiyuan-Liupanshan fault, northeastern Tibetan Plateau

Author

Li, Y. C., Shan, X. J., Qu, C. Y., Zhang, Y. F., Song, X. G., Jiang, Y., Zhang, G. H., Nocquet, Jean-Mathieu, Gong, W. Y., Gan, W. J., and Wang, C. S.

Subjects
Haiyuan-Liupanshan fault, GPS, Fault interseismic coupling, Strain
Abstract

Based on the dense GPS velocity field in the northeastern margin of the Tibetan Plateau from 1999 to 2016, we have produced the deformation and strain characteristics of the Haiyuan fault and the Liupanshan fault. Estimated long-term slip rate along the Haiyuan-Liupanshan fault zones show a gradual decrease from 6.4 +/- 1.6 mm/yr at the Tuolaishan fault to 2.9 +/- 1.2 mm/yr at the Southern Liupanshan fault. Left-lateral thrusting movement was inverted for the Xiangshan-Tianjingshan fault (XS-TJS), which has an average slip rate of 2.1 +/- 3.4 mm/yr during the study period. We also calculated the heterogeneous distribution of interseismic coupling along the fault zones. Our result also shows the locking depth of the Tianzhu seismic gap is 22 km. The slip rate deficit, the seismic moment accumulation rate, and the Coulomb stress accumulation rate are high on the fault planes, whereas the second invariant of the strain rate is low at the surface. The Liupanshan fault is locked to a depth of 23 km, and the corresponding seismic moment accumulation rate on the fault plane is high, while the strain rate at the surface is low. The accumulated strain along the Tianzhu seismic gap and the Liupanshan fault could be balanced by earthquakes with magnitudes of Mw7.9 and Mw7.4, considering the absence of large earthquakes over the last 1000 years and 1400 years respectively. The Haiyuan segments had ruptured during 1920 Haiyuan earthquake, and the estimated locking depth for period 1999-2016 is 5-10 km. Its seismic moment accumulation rate at depth is low and the strain rate at the surface is high. Our result indicates that 70% of the strike-slip along the Haiyuan segments transforms into thrusting along the Liupanshan fault, while the remaining 30% is related to the orogeny of the Liupanshan. For slip between the Haiyuan fault and the XS-TJS, about 27-34% of the slip is partitioned on the XS-TJS.

Published
2017

68. A Global Database of Strong‐Motion Displacement GNSS Recordings and an Example Application to PGD Scaling

Author

Ruhl, Christine J., primary, Melgar, Diego, additional, Geng, Jianghui, additional, Goldberg, Dara E., additional, Crowell, Brendan W., additional, Allen, Richard M., additional, Bock, Yehuda, additional, Barrientos, Sergio, additional, Riquelme, Sebastian, additional, Baez, Juan Carlos, additional, Cabral‐Cano, Enrique, additional, Pérez‐Campos, Xyoli, additional, Hill, Emma M., additional, Protti, Marino, additional, Ganas, Athanassios, additional, Ruiz, Mario, additional, Mothes, Patricia, additional, Jarrín, Paul, additional, Nocquet, Jean‐Mathieu, additional, Avouac, Jean‐Phillipe, additional, and D'Anastasio, Elisabetta, additional

Published
2018
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72. Subducted oceanic relief locks the shallow megathrust in central Ecuador

Author

Collot, Jean-julien, Sanclemente, Eddy, Nocquet, Jean-mathieu, Lepretre, Angelique, Ribodetti, Alessandra, Jarrin, Paul, Chlieh, Mohamed, Graindorge, David, Charvis, Philippe, Collot, Jean-julien, Sanclemente, Eddy, Nocquet, Jean-mathieu, Lepretre, Angelique, Ribodetti, Alessandra, Jarrin, Paul, Chlieh, Mohamed, Graindorge, David, and Charvis, Philippe

Abstract

Whether subducted oceanic reliefs such as seamounts promote seismic rupture or aseismic slip remains controversial. Here we use swath bathymetry, prestack depth-migrated multichannel seismic reflection lines, and wide-angle seismic data collected across the central Ecuador subduction segment to reveal a broad similar to 55kmx50km, similar to 1.5-2.0km high, low height-to-width ratio, multipeaked, sediment-bare, shallow subducted oceanic relief. Owing to La Plata Island and the coastline being located, respectively, similar to 35km and similar to 50-60km from the trench, GPS measurements allow us to demonstrate that the subducted oceanic relief spatially correlates to a shallow, similar to 80kmx55km locked interplate asperity within a dominantly creeping subduction segment. The oceanic relief geometrical anomaly together with its highly jagged topography, the absence of a subduction channel, and a stiff erosive oceanic margin are found to be long-term geological characteristics associated with the shallow locking of the megathrust. Although the size and level of locking observed at the subducted relief scale could produce an M-w >7+ event, no large earthquakes are known to have happened for several centuries. On the contrary, frequent slow slip events have been recorded since 2010 within the locked patch, and regular seismic swarms have occurred in this area during the last 40years. These transient processes, together with the rough subducted oceanic topography, suggest that interplate friction might actually be heterogeneous within the locked patch. Additionally, we find that the subducted relief undergoes internal shearing and produces a permanent flexural bulge of the margin, which uplifted La Plata Island. Plain Language Summary Subducted seamounts play an important but still uncertain role in earthquake rupture processes, as seamounts are considered to subduct either aseismically or seismically. We use marine geophysical data across the central Ecuador convergen

Published
2017
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73. Partitioning of oblique convergence in the Norther Andes subduction zone: Migration history and the present-day boundary of the North Andean Sliver in Ecuador

Author

Alvarado, A., Audin, Laurence, Nocquet, Jean-Mathieu, Jaillard, Etienne, Mothes, P., Jarrin, P., Segovia, M., Rolandone, F., Cisneros, D., instituto Geofísico, Escuela Politécnica Nacional, Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Géoazur (GEOAZUR 7329), 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)-Université Côte d'Azur (UCA), Institut des Sciences de la Terre de Paris (iSTeP), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Escuela Politécnica Nacional (EPN), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), 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, and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)

Subjects
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract

International audience; Along the Ecuadorian margin, oblique subduction induces deformation of the overriding continental plate. For the last 15 Ma, both exhumation and tectonic history of Ecuador suggest that the northeastward motion of the North Andean Sliver (NAS) was accompanied by an eastward migration of its eastern boundary and successive progressively narrowing restraining bends. Here we present geologic data, earthquake epicenters, focal mechanisms, GPS results, and a revised active fault map consistent with this new kinematic model. All data sets concur to demonstrate that active continental deformation is presently localized along a single major fault system, connecting fault segments from the Gulf of Guayaquil to the eastern Andean Cordillera. Although secondary faults are recognized within the Cordillera, they accommodate a negligible fraction of relative motion compared to the main fault system. The eastern limit is then concentrated rather than distributed as first proposed, marking a sharp boundary between the NAS, the Inca sliver, and the Subandean domain overthrusting the South American craton. The NAS limit follows a northeast striking right-lateral transpressional strike-slip system from the Gulf of Guayaquil (Isla Puná) to the Andean Cordillera and with the north-south striking transpressive faults along the eastern Andes. Eastward migration of the restraining belt since the Pliocene, abandonment of the sutures and reactivation of north-south striking ancient fault zones lead to the final development of a major tectonic boundary south and east of the NAS, favoring its extrusion as a continental sliver, accommodating the oblique convergence of the Nazca oceanic plate toward South America.

Published
2016

74. A mixed seismic-aseismic stress release episode in the Andean subduction zone

Author

Villegas-Lanza, J. C., Nocquet, Jean-Mathieu, Rolandone, F., Vallée, Martin, Tavera, H., Bondoux, Francis, Tran, T., Martin, Xavier, and Chlieh, Mohamed

Abstract

In subduction zones, stress is released by earthquakes and transient aseismic slip. The latter falls into two categories: slow slip and afterslip. Slow-slip events emerge spontaneously during the interseismic phase, and show a progressive acceleration of slip with a negligible contribution of synchronous tremors or microseismicity to the energy, or moment release(1-12). In contrast, afterslip occurs immediately after large and moderate earthquakes, decelerates over time, and releases between 20 and 400% of the moment released by the preceding earthquake(13-18). Here we use seismic and GPS data to identify transient aseismic slip that does not fit into either of these categories. We document a seismic-aseismic slip sequence which occurred at shallow depths along a weakly coupled part of the Andean subduction zone(19) in northern Peru and lasted seven months. The sequence generated several moderate earthquakes that together account for about 25% of the total moment released during the full sequence, equivalent to magnitude 6.7. Transient slip immediately followed two of the earthquakes, with slip slowing at a logarithmic rate. Considered separately, the moment released by transient slip following the second earthquake was more than 1,000% of the moment released during the earthquake itself, a value incompatible with classical models of afterslip. Synchronous seismic swarms and aseismic slipmay therefore definea stress-release process that is distinct from slow-slip events and afterslip.

Published
2016

75. Reassessing the complexity of the rupture of the 2010 Jia-Shian earthquake (Mw 6.2) in Southwestern Taiwan by inverting jointly teleseismic, strong-motion and CGPS data

Author

Lin, K. C., Delouis, B., Flu, J. C., Nocquet, Jean-Mathieu, and Mozziconacci, L.

Subjects
GPS, Jia-Shian earthquake, Taiwan, Earthquake source, Slip inversion
Abstract

A new interpretation is proposed for the 2010 Jia-Shian earthquake (Mw 62) which occurred on March 4, 2010 in southwestern Taiwan. Among the few tens of CGPS stations which recorded the mainshock at a distance less than 50 km we identified a few stations displaying, horizontal displacements in disagreement with the dominant pattern of horizontal coseismic motion. Based on this observation, we find that a secondary rupture plane explains these peculiar motions and helps improving the modeling of the overall set of CGPS stations. We also model the teleseismic and strong-motion records to refine the rupture model. Finally, we obtain the slip distribution on a two-fault model by the joint inversion of all three datasets (CGPS, teleseismic, and strong-motion). The main fault plane is consistent with previous studies. It corresponds to a N311 degrees E fault dipping 33 degrees to the NE, with left-lateral-reverse oblique slip, likely related to the Chishan transfer fault zone (CTFZ). We find that the earthquake started with a sharp slip patch localized at the hypocenter. The secondary rupture plane is a N20 degrees E thrust fault related to the Lungchuan anticline. Faulting on the main NW-SE plane during the Jia-Shian earthquake and"stress inversions from previous studies both suggest a direction of maximum horizontal compression oriented NE-SW in the area of the earthquake, very different from the dominant NW-SE compression direction in Taiwan. We propose that such a variation can be related to a stress deviation in the immediate vicinity of the CTFZ, in a similar way as observed along the San Andreas Fault in California. On the other hand, rupture on the secondary fault plane associated with the Lungchuan anticline appears to be compatible with the dominant compression in Taiwan.

Published
2016

76. Shallow earthquake inhibits unrest near Chiles-Cerro Negro volcanoes, Ecuador-Colombian border

Author

Ebmeier, S. K., Elliott, J. R., Nocquet, Jean-Mathieu, Biggs, J., Mothes, P., Jarrin, P., Yepez, M., Aguaiza, S., Lundgren, P., and Samsonov, S. V.

Subjects
volcanic hazard, InSAR, earthquake, GPS
Abstract

Magma movement or reservoir pressurisation can drive swarms of low-magnitude volcano-tectonic earthquakes, as well as occasional larger earthquakes (>M5) on local tectonic faults. Earthquakes >M5 near volcanoes are challenging to interpret in terms of evolving volcanic hazard, but are often associated with eruptions, and in some cases enhance the ascent of magma. We present geodetic observations from the first episode of unrest known to have occurred near Chiles and Cerro Negro de Mayasquer volcanoes on the Ecuador-Colombian border. A swarm of volcano-tectonic seismicity in October 2014 culminated in a M-w 5.6 earthquake south of the volcanoes. Satellite radar data spanning this earthquake detect displacements that are consistent with dextral oblique slip on a reverse fault at depths of 1.4-3.4 km within a SSW-NNE trending fault zone that last ruptured in 1886. GPS station measurements capture 20 days of uplift before the earthquake, probably originating from a pressure source similar to 10-15 km south of Volcan Chiles, at depths exceeding 13 km. After the Mw 5.6 earthquake, uplift ceased and the rate of seismicity began to decrease. Potential mechanisms for this decline in activity include a decrease in the rate of movement of magma into the shallow crust, possibly caused by the restriction of fluid pathways. Our observations demonstrate that an earthquake triggered during volcanic unrest can inhibit magmatic processes, and have implications for the hazard interpretation of the interactions between earthquakes and volcanoes.

Published
2016

80. A detailed source model for the M_w9.0 Tohoku-Oki earthquake reconciling geodesy, seismology, and tsunami records

Author

Bletery, Quentin, Sladen, Anthony, Delouis, Bertrand, Vallée, Martin, Nocquet, Jean-Mathieu, Rolland, Lucie, and Jiang, Junle

Abstract

The 11 March 2011 M_w9.0 Tohoku-Oki earthquake was recorded by an exceptionally large amount of diverse data offering a unique opportunity to investigate the details of this major megathrust rupture. Many studies have taken advantage of the very dense Japanese onland strong motion, broadband, and continuous GPS networks in this sense. But resolution tests and the variability in the proposed solutions have highlighted the difficulty to uniquely resolve the slip distribution from these networks, relatively distant from the source region, and with limited azimuthal coverage. In this context, we present a finite fault slip joint inversion including an extended amount of complementary data (teleseismic, strong motion, high-rate GPS, static GPS, seafloor geodesy, and tsunami records) in an attempt to reconcile them into a single better resolved model. The inversion reveals a patchy slip distribution with large slip (up to 64 m) mostly located updip of the hypocenter and near the trench. We observe that most slip is imaged in a region where almost no earthquake was recorded before the main shock and around which intense interplate seismicity is observed afterward. At a smaller scale, the largest slip pattern is imaged just updip of an important normal fault coseismically activated. This normal fault has been shown to be the mark of very low dynamic friction allowing extremely large slip to propagate up to the free surface. The spatial relationship between this normal fault and our slip distribution strengthens its key role in the rupture process of the Tohoku-Oki earthquake.

Published
2014

81. Active tectonics in Quito, Ecuador,assessed by geomorphological studies,GPS data,and crustal seismicity

Author

Alvarado, A., Audin, Laurence, Nocquet, Jean-Mathieu, Lagreulet, S., Segovia, M., Font, Yvonne, Lamarque, G., Yepes, H., Mothes, P., Rolandone, F., Jarrin, P., and Quidelleur, X.

Subjects
Active tectonics, Seismicity, Geodesy, Continental deformation
Abstract

The Quito Fault System (QFS) extends over 60km along the Interandean Depression in northern Ecuador. Multidisciplinary studies support an interpretation in which two major contemporaneous fault systems affect Quaternary volcanoclastic deposits. Hanging paleovalleys and disruption of drainage networks attest to ongoing crustal deformation and uplift in this region, further confirmed by 15 years of GPS measurements and seismicity. The resulting new kinematic model emphasizes the role of the N-S segmented, en echelon eastward migrating Quito Fault System (QFS). Northeast of this major tectonic feature, the strike-slip Guayllabamba Fault System (GFS) aids the eastward transfer of the regional strain toward Colombia. These two tectonic fault systems are active, and the local focal mechanisms are consistent with the direction of relative GPS velocities and the regional stress tensor. Among active features, inherited N-S direction sutures appear to play a role in confining the active deformation in the Interandean Depression. The most frontal of the Quito faults formed at the tip of a blind thrust, dipping 40 degrees W, is most probably connected at depth to inactive suture to the west. A new GPS data set indicates active shortening rates for Quito blind thrust of up to 4mm/yr, which decreases northward along the fold system as it connects to the strike-slip Guayllabamba Fault System. The proximity of these structures to the densely populated Quito region highlights the need for additional tectonic studies in these regions of Ecuador to generate further hazard assessments.

Published
2014

82. A detailed source model for the M(w)9.0 Tohoku-Oki earthquake reconciling geodesy, seismology, and tsunami records

Author

Bletery, Q., Sladen, A., Delouis, B., Vallée, Martin, Nocquet, Jean-Mathieu, Rolland, L., and Jiang, J. L.

Subjects
source, earthquake, joint inversion, Tohoku, slip model
Abstract

The 11 March 2011 M(w)9.0 Tohoku-Oki earthquake was recorded by an exceptionally large amount of diverse data offering a unique opportunity to investigate the details of this major megathrust rupture. Many studies have taken advantage of the very dense Japanese onland strong motion, broadband, and continuous GPS networks in this sense. But resolution tests and the variability in the proposed solutions have highlighted the difficulty to uniquely resolve the slip distribution from these networks, relatively distant from the source region, and with limited azimuthal coverage. In this context, we present a finite fault slip joint inversion including an extended amount of complementary data (teleseismic, strong motion, high-rate GPS, static GPS, seafloor geodesy, and tsunami records) in an attempt to reconcile them into a single better resolved model. The inversion reveals a patchy slip distribution with large slip (up to 64 m) mostly located updip of the hypocenter and near the trench. We observe that most slip is imaged in a region where almost no earthquake was recorded before the main shock and around which intense interplate seismicity is observed afterward. At a smaller scale, the largest slip pattern is imaged just updip of an important normal fault coseismically activated. This normal fault has been shown to be the mark of very low dynamic friction allowing extremely large slip to propagate up to the free surface. The spatial relationship between this normal fault and our slip distribution strengthens its key role in the rupture process of the Tohoku-Oki earthquake.

Published
2014

83. Intense interface seismicity triggered by a shallow slow slip event in the Central Ecuador subduction zone

Author

Vallée, Martin, Nocquet, Jean-Mathieu, Battaglia, J., Font, Yvonne, Segovia, M., Régnier, Marc, Mothes, P., Jarrin, P., Cisneros, D., Vaca, S., Yepes, H., Martin, Xavier, Bethoux, N., Chlieh, Mohamed, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto Geofísico, Escuela Politécnica Nacional (EPN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), IGM-EC, instituto Geofísico, 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]), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Escuala Politec Nacl, Institut Geofis, and Escuela Politécnica Nacional

Subjects
seismic swarm, seismic cycle, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, subduction interface, microseismicity, slow slip event
Abstract

International audience; We document a 1 week long slow slip event (SSE) with an equivalent moment magnitude of 6.0-6.3 which occurred in August 2010 below La Plata Island (Ecuador), south of the rupture area of the 1906 Mw = 8.8 megathrust earthquake. GPS data reveal that the SSE occurred at a depth of about 10 km, within the downdip part of a shallow (

Published
2013

84. Seismotectonics of the 2008 and 2009 Qaidam earthquakes and its implication for regional tectonics

Author

Chen, G. H., Xu, X. W., Zhu, A. L., Zhang, X. Q., Yuan, R. M., Klinger, Y., and Nocquet, Jean-Mathieu

Subjects
fault, Xitieshan fault, structure style, Zongwulongshan, seismotectonics, Qaidam earthquakes
Abstract

Three magnitude >6 earthquakes struck Qaidam, Qinghai province, China, in November 10th 2008, August 28th and 31st 2009 respectively. The Zongwulongshan fault has often been designated as the active seismogenic structure, although it is at odd with the data. Our continuous GPS station (CGPS), the Xiao Qaidam station, located in the north of the Qaidam basin, is less than 30 km to the southwest of the 2008 earthquake. This CGPS station recorded the near field co-seismic deformation. Here we analyzed the co-seismic dislocation based on the GPS time series and the rupture processes from focal mechanism for the three earthquakes. The aftershocks were relocated to constrain the spatial characteristics of the 2008 and 2009 Qaidam earthquakes. Field geological and geomorphological investigation and interpretation of satellite images show that the Xitieshan fault and Zongwulongshan fault were activated as left lateral thrust during the late Quaternary. Evidence of folding can also be identified. Integrated analyses based on our data and the regional tectonic environment show that the Xitieshan fault is the fault responsible for the 2008 Qaidam earthquake, which is a low dip angle thrust with left lateral strike slip. The Zongwulongshan fault is the seismogenic fault of the 2009 earthquakes, which is a south dipping back thrust of the northern marginal thrust system of the Qaidam basin. Folding takes a significant part of the deformation in the northern marginal thrust system of the Qaidam basin, dominating the contemporary structure style of the northern margin of the Qaidam basin and Qilianshan tectonic system. In this region, this fault and fold system dominates the earthquake activities with frequent small magnitude earthquakes.

Published
2013

86. Quantification of strain rate in the Western Alps using geodesy: comparisons with seismotectonics

Author

Delacou, Bastien, Sue, Christian, Nocquet, Jean-Mathieu, Champagnac, Jean-Daniel, Allanic, Cécile, Burkhard, Martin, Delacou, Bastien, Sue, Christian, Nocquet, Jean-Mathieu, Champagnac, Jean-Daniel, Allanic, Cécile, and Burkhard, Martin

Abstract

The contrasted seismotectonic regime of the Western Alps is characterized by radial extension in the high chain, combined with local compressive areas at the foothill of the belt, and everywhere occurrence of transcurrent tectonics. Here, we compare this seismotectonic regime to a large-scale compilation of GPS measurements in the Western Alpine realm. Our analysis is based on the raw GPS database, which give the measured velocity field with respect to the so called “stable Europe”, and an interpolated velocity field, in order to smooth the database on a more regular mesh. Both strain rate and rotational components of the deformation are investigated. The strain rate field shows patch-like structure, with extensional areas located in the core and to the North of the belt and compressional areas located in its periphery. Although the GPS deformation fields (both raw and interpolated) are more spatially variable than the seismotectonic field, a good qualitative correlation is established with the seismotectonic regionalization of the deformation. The rotation rate fields (both raw and interpolated) present counterclockwise rotations in the innermost part of the belt and a surprising continuous zone of clockwise rotations following the arc-shape geometry of the Western Alps along their external border. We interpret this new result in term of a counterclockwise rotation of the Apulia plate with respect to the stable Europe. This tectonic scheme may induce clockwise rotations of crustal block along the large strike-slip fault system, which runs in the outer part of the belt, from the Rhône-Simplon fault to the Belledonne fault and Southeastward, to the High-Durance and Argentera fault.

Published
2009

91. Deformation in the Jura Mountains (France): First results from semi-permanent GPS measurements

Author

Tregoning, Paul, Walpersdorf, Andrea, Baize, Stephane, Calais, Eric, Nocquet, Jean-Mathieu, Tregoning, Paul, Walpersdorf, Andrea, Baize, Stephane, Calais, Eric, and Nocquet, Jean-Mathieu

Abstract

New GPS estimates of relative motion across the Jura Mountain Belt with respect to the Eurasian Plate indicate less than 1 mm/yr of convergence, considerably less than previous estimates. Velocity uncertainties have been evaluated by several methods and

Published
2006

95. A kinematic model for the East African Rift

Author

Stamps, D. Sarah, primary, Calais, Eric, additional, Saria, Elifuraha, additional, Hartnady, Chris, additional, Nocquet, Jean-Mathieu, additional, Ebinger, Cynthia J., additional, and Fernandes, Rui M., additional

Published
2008
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97. REGAL; reseau GPS permanent dans les Alpes occidentales; configuration et premiers resultats

Author

Calais, Eric, primary, Bayer, Roger, additional, Chery, Jean, additional, Cotton, Fabrice, additional, Doerflinger, Erik, additional, Flouzat, Mireille, additional, Jouanne, Francois, additional, Kasser, Michel, additional, Laplanche, Maurice, additional, Maillard, Didier, additional, Martinod, Joseph, additional, Mathieu, Franck, additional, Nicolon, Philippe, additional, Nocquet, Jean-Mathieu, additional, Scotti, Oona, additional, Serrurier, Laurent, additional, Tardy, Marc, additional, and Vigny, Christophe, additional

Published
2001
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99. Quantification of strain rate in the Western Alps using geodesy: comparisons with seismotectonics

Author

Delacou, Bastien, Sue, Christian, Nocquet, Jean-Mathieu, Champagnac, Jean-Daniel, Allanic, Cécile, Burkhard, Martin, Delacou, Bastien, Sue, Christian, Nocquet, Jean-Mathieu, Champagnac, Jean-Daniel, Allanic, Cécile, and Burkhard, Martin

Abstract

The contrasted seismotectonic regime of the Western Alps is characterized by radial extension in the high chain, combined with local compressive areas at the foothill of the belt, and everywhere occurrence of transcurrent tectonics. Here, we compare this seismotectonic regime to a large-scale compilation of GPS measurements in the Western Alpine realm. Our analysis is based on the raw GPS database, which give the measured velocity field with respect to the so called “stable Europe”, and an interpolated velocity field, in order to smooth the database on a more regular mesh. Both strain rate and rotational components of the deformation are investigated. The strain rate field shows patch-like structure, with extensional areas located in the core and to the North of the belt and compressional areas located in its periphery. Although the GPS deformation fields (both raw and interpolated) are more spatially variable than the seismotectonic field, a good qualitative correlation is established with the seismotectonic regionalization of the deformation. The rotation rate fields (both raw and interpolated) present counterclockwise rotations in the innermost part of the belt and a surprising continuous zone of clockwise rotations following the arc-shape geometry of the Western Alps along their external border. We interpret this new result in term of a counterclockwise rotation of the Apulia plate with respect to the stable Europe. This tectonic scheme may induce clockwise rotations of crustal block along the large strike-slip fault system, which runs in the outer part of the belt, from the Rhône-Simplon fault to the Belledonne fault and Southeastward, to the High-Durance and Argentera fault.

100. Present-day uplift of the European Alps: Evaluating mechanisms and models of their relative contributions

Author

Pierre G. Valla, Laurent Jolivet, Carole Petit, Sean D. Willett, Sébastien Castelltort, Pietro Sternai, Andrea Walpersdorf, Jean-Mathieu Nocquet, Thorsten W. Becker, Laurent Husson, Giorgio Spada, Christian Sue, Andrea Di Giulio, Enrico Serpelloni, Claudio Faccenna, Sternai, Pietro, Sue, Christian, Husson, Laurent, Serpelloni, Enrico, Becker, Thorsten W., Willett, Sean D., Faccenna, Claudio, Di Giulio, Andrea, Spada, Giorgio, Jolivet, Laurent, Valla, Pierre, Petit, Carole, Nocquet, Jean-Mathieu, Walpersdorf, Andrea, Castelltort, Sébastien, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Laboratory of Experimental Tectonics, Università degli Studi Roma Tre, Dipartimento di Scienze della Terra e dell'Ambiente [Pavia], Università degli Studi di Pavia, Dipartimento di Scienze di Base e Fondamenti, Università degli Studi di Urbino 'Carlo Bo', Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), 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, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), University of Geneva, Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Department of Earth Sciences [ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Università di Pavia, Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Sternai, P, Sue, C, Husson, L, Serpelloni, E, Becker, T, Willett, S, Faccenna, C, Di Giulio, A, Spada, G, Jolivet, L, Valla, P, Petit, C, Nocquet, J, Walpersdorf, A, and Castelltort, S

Subjects
European Alps Vertical displacement rate Deglaciation Erosion Lithospheric structural changes Mantle flow, Vertical displacement rate, 010504 meteorology & atmospheric sciences, European Alp, Present day, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Lithospheric structural changes, Mantle convection, Lithosphere, Deglaciation, ddc:550, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Mantle flow, 15. Life on land, Lithospheric structural change, Tectonics, 13. Climate action, Erosion, Slab, General Earth and Planetary Sciences, Upwelling, European Alps, Earth and Planetary Sciences (all), Surface mass, Geology
Abstract

Recent measurements of surface vertical displacements of the European Alps show a correlation between vertical velocities and topographic features, with widespread uplift at rates of up to ~2–2.5 mm/a in the North-Western and Central Alps, and ~1 mm/a across a continuous region from the Eastern to the South-Western Alps. Such a rock uplift rate pattern is at odds with the horizontal velocity field, characterized by shortening and crustal thickening in the Eastern Alps and very limited deformation in the Central and Western Alps. Proposed mechanisms of rock uplift rate include isostatic response to the last deglaciation, long-term erosion, detachment of the Western Alpine slab, as well as lithospheric and surface deflection due to mantle convection. Here, we assess previous work and present new estimates of the contributions from these mechanisms. Given the large range of model estimates, the isostatic adjustment to deglaciation and erosion are sufficient to explain the full observed rate of uplift in the Eastern Alps, which, if correct, would preclude a contribution from horizontal shortening and crustal thickening. Alternatively, uplift is a partitioned response to a range of mechanisms. In the Central and Western Alps, the lithospheric adjustment to deglaciation and erosion likely accounts for roughly half of the rock uplift rate, which points to a noticeable contribution by mantle-related processes such as detachment of the European slab and/or asthenospheric upwelling. While it is difficult to independently constrain the patterns and magnitude of mantle contributions to ongoing Alpine vertical displacements at present, future data should provide additional insights. Regardless, interacting tectonic and surface mass redistribution processes, rather than an individual forcing, best explain ongoing Alpine elevation changes.

Published
2019

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