Ground deformation monitoring of the eruption offshore Mayotte

In May 2018, the Mayotte island, located in the Indian Ocean, was affected by an unprecedented seismic crisis, followed by anomalous on-land surface displacements in July 2018. Cumulatively from July 1, 2018 to December 31, 2021, the horizontal displacements were approximately 21 to 25 cm eastward, and subsidence was approximately 10 to 19 cm. The study of data recorded by the on-land GNSS network, and their modeling coupled with data from ocean bottom pressure gauges, allowed us to propose a magmatic origin of the seismic crisis with the deflation of a deep source east of Mayotte, that was confirmed in May 2019 by the discovery of a submarine eruption, 50 km offshore of Mayotte ([Feuillet et al., 2021]). Despite a non-optimal network geometry and receivers located far from the source, the GNSS data allowed following the deep dynamics of magma transfer, via the volume flow monitoring, throughout the eruption

Les plateformes instrumentales sismologiques

Le parc national d'instruments Sismologiques Mobiles terrestres (SisMob), est hébergé et géré à l'Osug/ISTerre (Grenoble) au sein du Service Instrumentations Géophysiques (Sig). Le parc compte 120 stations de type large-bande (LB) ou moyenne-bande (MB), composées de capteurs et numériseurs dissociés pouvant être connectés pour transmettre les données en temps réel

Les plateformes instrumentales sismologiques

Le parc national d'instruments Sismologiques Mobiles terrestres (SisMob), est hébergé et géré à l'Osug/ISTerre (Grenoble) au sein du Service Instrumentations Géophysiques (Sig). Le parc compte 120 stations de type large-bande (LB) ou moyenne-bande (MB), composées de capteurs et numériseurs dissociés pouvant être connectés pour transmettre les données en temps réel

Les plateformes instrumentales sismologiques

Le parc national d'instruments Sismologiques Mobiles terrestres (SisMob), est hébergé et géré à l'Osug/ISTerre (Grenoble) au sein du Service Instrumentations Géophysiques (Sig). Le parc compte 120 stations de type large-bande (LB) ou moyenne-bande (MB), composées de capteurs et numériseurs dissociés pouvant être connectés pour transmettre les données en temps réel

Les plateformes instrumentales sismologiques

Le parc national d'instruments Sismologiques Mobiles terrestres (SisMob), est hébergé et géré à l'Osug/ISTerre (Grenoble) au sein du Service Instrumentations Géophysiques (Sig). Le parc compte 120 stations de type large-bande (LB) ou moyenne-bande (MB), composées de capteurs et numériseurs dissociés pouvant être connectés pour transmettre les données en temps réel

PISE: A test and calibration facility dedicated to seismological instrumentation. Feedback on a batch of 110 stations

International audienceSeismological projects are increasingly based on a subsequent instrumentation. The trend is clearly toward a network densification and the growth of seismometers parks. This occurs at the international, national and local levels, and concerns both temporary research experiments and permanent observatories. Despite technical constraints specific to each project, they all require detailed monitoring of the status and characteristics of the instrumentation, and an efficient maintenance. We set up a technical platform at the EOST (Ecole et Observatoire des Sciences de la Terre (Univ. Strasbourg)): the Seismological Instrumental Platform of EOST (PISE). Using dedicated seismological pillars, we test, validate, calibrate, maintain and monitor over time seismometers and dataloggers characteristics.We use several calibration methods, both relative and absolute. In order to increase the signal to noise ratio, we remotely perform them, while instruments are in quiet conditions on its pillar. For this purpose, we present here our operating mode and some specially developped network devices able to control instrument calibration. As PISE has been chosen as the instrumentation facility of the broad-band French network RESIF, currently under contruction, we already tested and calibrated 110 stations acquired in early 2017. We present here a feed-back on those instruments performances, and their expected dispersions on the whole batch, before field deployment, but also on our calibration procedures, roughly tried out with several operators and a not negligible number of units

PISE: la Plateforme Instrumentale Sismologique de l'EOST

International audienc

Seismotectonics in Northeastern France and neighboring regions

International audienceThe region of northeastern France is affected by low-magnitude background seismicity, with the rare occurrence of moderate earthquakes, which gives this region a non-negligible seismic risk. We provide an overview of the seismicity and seismotectonics of this intraplate domain and of its subregions: the Upper-Rhine Graben (URG), the external range and foreland of Jura, the Vosges, northern France and southern Belgium. Previously published catalogues over historical and instrumental times are used, and the epicentral distribution of earthquakes is compared to known tectonic structures, and the recently computed deformation field. Although no large earthquakes with M w > 6.0 occurred since the 1356 Basel seismic event (Io IX, MKS), the recent identification of active faults suggests periods of high seismic strain rates in the past. The origin of the seismic activity in each of these sub-regions, characterized by low to very-low strain rates, is attributed to pre-existing faults reactivated under specific natural or anthropogenic conditions