Séisme de Barcelonnette. 7 avril 2014. La Condamine-Châtelard. Cheminées tombées.

Fallen and secured chimneys in the centre of the village of La Condamine-Châtelard. The damage mainly concerns the stone houses in the historic centre of the municipality along the Ubaye river, where there are vulnerable buildings, as well as in the part below at Champ Fellez. About fifteen chimneys have been affected in the centre of the village (end of the Parpaillon). The Condamine-Châtelard is located 6 km from the epicentre of the April 7 earthquake and the intensity of the tremors felt is VI on the European intensity scale EMS-98. This photo was taken during the Macroseismic Response Group mission to the site after the earthquake. Composed of six experts, the group arrived in Barcelona on April 14, 2014 for a three-day mission. With a magnitude of 5.2 (MW), its epicentre was located approximately 6 km west southwest of the commune of Saint-Paul-sur-Ubaye and 11 km north of Barcelonnette, near the border of the departments of Alpes-de-Haute-Provence and Hautes-Alpes.Cheminées tombées et sécurisées dans le centre du village de La Condamine-Châtelard. Les dégâts portent essentiellement sur les maisons de pierre au centre historique de la commune le long de l’Ubaye, où l’on trouve des bâtiments vulnérables, ainsi que dans la partie en contrebas au Champ Fellez. Une quinzaine de cheminées ont été affectées dans le centre du village (fin du Parpaillon). La Condamine-Châtelard se situe à 6 km de l’épicentre du séisme du 7 avril et l’intensité des secousses ressenties est de VI sur l’échelle d’intensité européenne EMS-98. Cette photo a été prise lors de la mission du Groupe d'intervention macrosismique qui s'est rendu sur place après le séisme. Composé de six experts, le groupe est arrivé à Barcelonnette le 14 avril 2014 pour une mission de trois jours. D'une magnitude 5.2 (MW), son épicentre se situait à environ 6 km à l’Ouest Sud-Ouest de la commune de Saint-Paul-sur-Ubaye et 11km au Nord de Barcelonnette, à proximité de la limite des départements des Alpes-de-Haute-Provence et des Hautes-Alpes

Séisme de Barcelonnette. 7 avril 2014. La Condamine-Châtelard. Glissement de Parpaillon

Landslide of Parpaillon on the commune of La Condamine-Châtelard: the earthquake created an 80 cm gap compared to the initial state. The Condamine-Châtelard is located 6 km from the epicentre of the April 7 earthquake and the intensity of the tremors felt is VI on the European intensity scale EMS-98. This photo was taken during the Macroseismic Response Group mission to the site after the earthquake. Composed of six experts, the group arrived in Barcelona on April 14, 2014 for a three-day mission. With a magnitude of 5.2 (MW), its epicentre was located approximately 6 km west southwest of the commune of Saint-Paul-sur-Ubaye and 11 km north of Barcelonnette, near the border of the departments of Alpes-de-Haute-Provence and Hautes-Alpes.Glissement de terrain de Parpaillon sur la commune de La Condamine-Châtelard : le séisme a créé un décalage de 80 cm par rapport à l'état initial. La Condamine-Châtelard se situe à 6 km de l’épicentre du séisme du 7 avril et l’intensité des secousses ressenties est de VI sur l’échelle d’intensité européenne EMS-98. Cette photo a été prise lors de la mission du Groupe d'intervention macrosismique qui s'est rendu sur place après le séisme. Composé de six experts, le groupe est arrivé à Barcelonnette le 14 avril 2014 pour une mission de trois jours. D'une magnitude 5.2 (MW), son épicentre se situait à environ 6 km à l’Ouest Sud-Ouest de la commune de Saint-Paul-sur-Ubaye et 11km au Nord de Barcelonnette, à proximité de la limite des départements des Alpes-de-Haute-Provence et des Hautes-Alpes

Fluxgate vector magnetometers: A multisensor device for ground, UAV, and airborne magnetic surveys

International audienceFluxgate magnetometers are quite uncommon in geophysics. Recent advances in calibration of the devices and their magnetic compensation ability led Institut de Physique du Globe de Stras-bourg to develop instruments for magnetic measurements at different scales for a wide range of applications — from submetric measurements on the ground to aircraft-conducted acquisition by unmanned aerial vehicles (UAVs). A case study on the aerial military base BA112 shows the usefulness of the instruments for the detection of underground pipes, unexploded ordnance, and archaeological remains

Dans la catégorie des méthodes de caractérisation des V S 30 et classes de sol, le gagnant est… : Principaux résultats du benchmark « InterPacific »

International audienceABSTRACT. The use of reliable characterization methods for site characterization (determination of soil classes, VS30, velocity profiles ...) is a major issue in many cases: application of EC8, site characterization... The methods conventionally used in geotechnics (cross-hole, down-hole) are expensive and need the drilling of boreholes. Other methods, based on the analysis of the dispersion of surface waves are non-invasive, but their processing requires a certain level of expertise and their use has long been criticized. To compare and analyze the differences between these different approaches, three sites benefited from several "invasive" and "non-invasive" measurements, processed by various teams within an international benchmark in a blind context ("InterPacific" project). The variability between results obtained with invasive methods is larger than what we expected initially. Conversely, even if they cannot reach the same vertical resolution, non-invasive methods have produced results much less scattered than what we expected. In terms of V S 30 determination, the resulting standard deviations are equivalent between invasive and non-invasive methods, or even lower for non-invasive methods.L'utilisation de méthodes de caractérisation fiables pour la caractérisation des sites (détermination des classes de sols, des V S 30, de profils de vitesse…) est un enjeu majeur dans de nombreux cas : application des EC8, caractérisation de sites… Les méthodes classiquement utilisées en géotechnique (cross-hole, down-hole) sont onéreuses et impliquent la réalisation de forage(s). D'autres méthodes, basées sur l'analyse de la dispersion des ondes de surfaces sont non-invasives, mais leur traitement demande un niveau certain d'expertise et leur emploi a longtemps été critiqué. Afin de comparer et d'analyser les écarts entre ces différentes approches, trois sites ont bénéficié de plusieurs mesures « invasives » et « non-invasives » traitées par plusieurs équipes internationales dans un contexte de benchmark en aveugle (projet « InterPacific »). La variabilité obtenue entre les résultats des méthodes invasives est plus grande que celle à laquelle nous nous attendions initialement. Inversement, et même si elles ne peuvent rivaliser en termes de résolution verticale, les méthodes non-invasives ont produit des résultats beaucoup moins dispersés que ce à quoi nous nous attentions. En termes de détermination du V S 30, les écarts-types obtenus sont équivalents entre méthodes invasives et non-invasives, voire inférieurs pour les méthodes non-invasives

Building a three dimensional model of the active Plio-Quaternary basin of Argostoli (Cephalonia Island, Greece): an integrated geophysical and geological approach

International audienceThis work is a multidisciplinary approach from geological and geophysical surveys to build a 3D geological model of Argostoli Basin (Cephalonia Island, Greece) aiming to be used for computational 3D simulation of seismic motion. Cephalonia Island is located at the north-western end of the Aegean subduction frontal thrust that is linked to the dextral Cephalonia Transform Fault (west of Cephalonia) where the seismic hazard is high in terms of earthquake frequency and magnitude. The Plio-Quaternary Koutavos-Argostoli basin site was selected within the French Research Agency PIA SINAPS@ project (www.institut-seism.fr/projets/sinaps/ - last accessed on July 14th 2019) to host a vertical accelerometer array. The long-term goal is to validate three-dimensional nonlinear numerical simulation codes to assess the site-specific amplification and nonlinearity. Herein the geological and geophysical surveys carried out from 2011 to 2017 are presented and in particular the complementary investigations that led to the identification of the main stratigraphic units and their structures. In addition, coral debris sampled from the vertical array deep borehole cores were used for 230Th/234U measurements, which confirmed the Pleistocene age of the Koutavos basin. The characterization of the three-dimensional structure of the stratigraphic units was achieved by coupling geological cross-sections (i.e., depth geometry) and geophysical surveys based of surface wave analysis

Building a Three Dimensional Model of Plio-Quaternary Basin of Argostoli (Cephalonia Island, Greece) From an Integrated Geophysical and Geological Approach to Perform Numerical Simulations of Seismic Motion

International audienceThe Cephalonia Island (Greece) area is located in the north-western end of the Aegean subduction frontal thrust that is linked to the dextral Cephalonia Transform Fault (west of Cephalonia). As the mean slip rate and the length of the Cephalonia Transform Fault are large, the seismic hazard is high in terms of earthquake frequency and magnitude. The Plio-Quaternary Koutavos-Argostoli basin site was selected within the French Research Agency PIA SINAPS@ project (www.institut-seism.fr/projets/sinaps/) to host a vertical accelerometer array. The long-term goal is to validate three-dimensional nonlinear numerical simulation codes to assess the site¬specific amplification and nonlinearity in the framework of seismic hazard assessment. Geological and geophysical surveys were carried out from 2011 to 2017. The aim of this work is to present i) the geological and structural context, ii) the complementary geological, geotechnical, and iii) the geophysical investigations that led to the identification of the main geotechnical bodies and their structures. The characterization of the three-dimensional structure of the stratigraphic units was achieved by coupling geological cross-sections (i.e., depth geometry) and HVSR/AVA geophysical surveys that were designed to identify the sedimentary body thickness. The data gathered allowed to build a three-dimensional geological model of the Argostoli basin. Starting from this point, a 3D numerical model on the same area was constructed using spectral element code known as SEM3D. Several simulations of seismic scenarios were performed, for the purpose of highlighting the importance of the use a representative model of the complexity of the wave path on the hazard assessment

Building a Three Dimensional Model of Plio-Quaternary Basin of Argostoli (Cephalonia Island, Greece) From an Integrated Geophysical and Geological Approach to Perform Numerical Simulations of Seismic Motion

International audienceThe Cephalonia Island (Greece) area is located in the north-western end of the Aegean subduction frontal thrust that is linked to the dextral Cephalonia Transform Fault (west of Cephalonia). As the mean slip rate and the length of the Cephalonia Transform Fault are large, the seismic hazard is high in terms of earthquake frequency and magnitude. The Plio-Quaternary Koutavos-Argostoli basin site was selected within the French Research Agency PIA SINAPS@ project (www.institut-seism.fr/projets/sinaps/) to host a vertical accelerometer array. The long-term goal is to validate three-dimensional nonlinear numerical simulation codes to assess the site¬specific amplification and nonlinearity in the framework of seismic hazard assessment. Geological and geophysical surveys were carried out from 2011 to 2017. The aim of this work is to present i) the geological and structural context, ii) the complementary geological, geotechnical, and iii) the geophysical investigations that led to the identification of the main geotechnical bodies and their structures. The characterization of the three-dimensional structure of the stratigraphic units was achieved by coupling geological cross-sections (i.e., depth geometry) and HVSR/AVA geophysical surveys that were designed to identify the sedimentary body thickness. The data gathered allowed to build a three-dimensional geological model of the Argostoli basin. Starting from this point, a 3D numerical model on the same area was constructed using spectral element code known as SEM3D. Several simulations of seismic scenarios were performed, for the purpose of highlighting the importance of the use a representative model of the complexity of the wave path on the hazard assessment

Building a Three Dimensional Model of Plio-Quaternary Basin of Argostoli (Cephalonia Island, Greece) From an Integrated Geophysical and Geological Approach to Perform Numerical Simulations of Seismic Motion

International audienceThe Cephalonia Island (Greece) area is located in the north-western end of the Aegean subduction frontal thrust that is linked to the dextral Cephalonia Transform Fault (west of Cephalonia). As the mean slip rate and the length of the Cephalonia Transform Fault are large, the seismic hazard is high in terms of earthquake frequency and magnitude. The Plio-Quaternary Koutavos-Argostoli basin site was selected within the French Research Agency PIA SINAPS@ project (www.institut-seism.fr/projets/sinaps/) to host a vertical accelerometer array. The long-term goal is to validate three-dimensional nonlinear numerical simulation codes to assess the site¬specific amplification and nonlinearity in the framework of seismic hazard assessment. Geological and geophysical surveys were carried out from 2011 to 2017. The aim of this work is to present i) the geological and structural context, ii) the complementary geological, geotechnical, and iii) the geophysical investigations that led to the identification of the main geotechnical bodies and their structures. The characterization of the three-dimensional structure of the stratigraphic units was achieved by coupling geological cross-sections (i.e., depth geometry) and HVSR/AVA geophysical surveys that were designed to identify the sedimentary body thickness. The data gathered allowed to build a three-dimensional geological model of the Argostoli basin. Starting from this point, a 3D numerical model on the same area was constructed using spectral element code known as SEM3D. Several simulations of seismic scenarios were performed, for the purpose of highlighting the importance of the use a representative model of the complexity of the wave path on the hazard assessment

Building a Three Dimensional Model of Plio-Quaternary Basin of Argostoli (Cephalonia Island, Greece) From an Integrated Geophysical and Geological Approach to Perform Numerical Simulations of Seismic Motion

International audienceThe Cephalonia Island (Greece) area is located in the north-western end of the Aegean subduction frontal thrust that is linked to the dextral Cephalonia Transform Fault (west of Cephalonia). As the mean slip rate and the length of the Cephalonia Transform Fault are large, the seismic hazard is high in terms of earthquake frequency and magnitude. The Plio-Quaternary Koutavos-Argostoli basin site was selected within the French Research Agency PIA SINAPS@ project (www.institut-seism.fr/projets/sinaps/) to host a vertical accelerometer array. The long-term goal is to validate three-dimensional nonlinear numerical simulation codes to assess the site¬specific amplification and nonlinearity in the framework of seismic hazard assessment. Geological and geophysical surveys were carried out from 2011 to 2017. The aim of this work is to present i) the geological and structural context, ii) the complementary geological, geotechnical, and iii) the geophysical investigations that led to the identification of the main geotechnical bodies and their structures. The characterization of the three-dimensional structure of the stratigraphic units was achieved by coupling geological cross-sections (i.e., depth geometry) and HVSR/AVA geophysical surveys that were designed to identify the sedimentary body thickness. The data gathered allowed to build a three-dimensional geological model of the Argostoli basin. Starting from this point, a 3D numerical model on the same area was constructed using spectral element code known as SEM3D. Several simulations of seismic scenarios were performed, for the purpose of highlighting the importance of the use a representative model of the complexity of the wave path on the hazard assessment