Antonio Saccone, Ungaretti

Avec cet ouvrage, Antonio Saccone, professeur à l’Université Federico II de Naples, réalise ce qu’il appelle lui-même « un’indagine » (p. 7) sur ce monstre sacré de la poésie italienne qu’est Giuseppe Ungaretti. Pour mener à bien son enquête, Antonio Saccone choisit de se pencher sur la vie et l’œuvre du poète, suivant une étude à la fois chronologique et thématique. C’est sur ce pari réussi que repose l’intérêt de cet ouvrage puisque rares sont les monographies ayant osé aborder l’auteur de ..

Antonio Saccone, Ungaretti

Avec cet ouvrage, Antonio Saccone, professeur à l’Université Federico II de Naples, réalise ce qu’il appelle lui-même « un’indagine » (p. 7) sur ce monstre sacré de la poésie italienne qu’est Giuseppe Ungaretti. Pour mener à bien son enquête, Antonio Saccone choisit de se pencher sur la vie et l’œuvre du poète, suivant une étude à la fois chronologique et thématique. C’est sur ce pari réussi que repose l’intérêt de cet ouvrage puisque rares sont les monographies ayant osé aborder l’auteur de ..

Antonio Saccone, Ungaretti

Avec cet ouvrage, Antonio Saccone, professeur à l’Université Federico II de Naples, réalise ce qu’il appelle lui-même « un’indagine » (p. 7) sur ce monstre sacré de la poésie italienne qu’est Giuseppe Ungaretti. Pour mener à bien son enquête, Antonio Saccone choisit de se pencher sur la vie et l’œuvre du poète, suivant une étude à la fois chronologique et thématique. C’est sur ce pari réussi que repose l’intérêt de cet ouvrage puisque rares sont les monographies ayant osé aborder l’auteur de ..

On a Fractional Stochastic Hodgkin-Huxley Model

International audienceThe model studied in this paper is a stochastic extension of the so-called neuron model introduced by Hodgkin and Huxley. In the sense of rough paths, the model is perturbed by a multiplicative noise driven by a fractional Brownian motion, with a vector field satisfying the viability condition of Coutin and Marie for $\mathbb R\times [0,1]^3$. An application to the modeling of the membrane potential of nerve fibers damaged by a neuropathy is provided

Seismicity and fault aseismic deformation caused by fluid injection in decametric in-situ experiments

International audienceSeismicity induced by fluid perturbations became an important societal concern since felt earthquakes (Mw up to 6) occurred after anthropogenic activities. In order to mitigate the risks associated with undesired seismicity, as well as to be able to use the micro-seismicity as a probe for in-depth investigation of fluid-driven processes, it is of crucial importance to understand the links between seismicity, fluid pressure and flow. We have developed a series of in-situ, decameter-scale experiments of fault zone reactivation by controlled fluid injection, in order to improve the near-source geophysical and hydromechanical observations. The deployed geophysical monitoring close to the injection allows one to cover the full frequency range of the fault responses from the static deformation to the very high-frequency seismic emissions (up to 4 kHz). Here, we focus on the microseismicity (Mw ∼ –4 to –3) recorded during two fluid injection experiments in low-permeable shale and highly-fractured limestone formations. In both experiments, the spatio-temporal distribution of the seismic events, the energy balance, and the seismic velocity changes of the fractured medium show that most of the deformation does not actually emit seismic signals. The induced deformation is mainly aseismic. Based on these high-resolution multiparametric observations in the near-field, we therefore proposed a new model for injection-induced seismicity: the seismicity is not directly induced by the increasing fluid pressure, but it is rather triggered by the stress perturbations transferred from the aseismic motion caused by the injection

Seismicity and fault aseismic deformation caused by fluid injection in decametric in-situ experiments

International audienceSeismicity induced by fluid perturbations became an important societal concern since felt earthquakes (Mw up to 6) occurred after anthropogenic activities. In order to mitigate the risks associated with undesired seismicity, as well as to be able to use the micro-seismicity as a probe for in-depth investigation of fluid-driven processes, it is of crucial importance to understand the links between seismicity, fluid pressure and flow. We have developed a series of in-situ, decameter-scale experiments of fault zone reactivation by controlled fluid injection, in order to improve the near-source geophysical and hydromechanical observations. The deployed geophysical monitoring close to the injection allows one to cover the full frequency range of the fault responses from the static deformation to the very high-frequency seismic emissions (up to 4 kHz). Here, we focus on the microseismicity (Mw ∼ –4 to –3) recorded during two fluid injection experiments in low-permeable shale and highly-fractured limestone formations. In both experiments, the spatio-temporal distribution of the seismic events, the energy balance, and the seismic velocity changes of the fractured medium show that most of the deformation does not actually emit seismic signals. The induced deformation is mainly aseismic. Based on these high-resolution multiparametric observations in the near-field, we therefore proposed a new model for injection-induced seismicity: the seismicity is not directly induced by the increasing fluid pressure, but it is rather triggered by the stress perturbations transferred from the aseismic motion caused by the injection

Energy of injection-induced seismicity predicted from in-situ experiments

Abstract The ability to predict the magnitude of an earthquake caused by deep fluid injections is an important factor for assessing the safety of the reservoir storage and the seismic hazard. Here, we propose a new approach to evaluate the seismic energy released during fluid injection by integrating injection parameters, induced aseismic deformation, and the distance of earthquake sources from injection. We use data from ten injection experiments performed at a decameter scale into fault zones in limestone and shale formations. We observe that the seismic energy and the hydraulic energy similarly depend on the injected fluid volume (V), as they both scale as V 3/2. They show, however, a large discrepancy, partly related to a large aseismic deformation. Therefore, to accurately predict the released seismic energy, aseismic deformation should be considered in the budget through the residual deformation measured at the injection. Alternatively, the minimal hypocentral distance from injection points and the critical fluid pressure for fault reactivation can be used for a better prediction of the seismic moment in the total compilation of earthquakes observed during these experiments. Complementary to the prediction based only on the injected fluid volume, our approach opens the possibility of using alternative monitoring parameters to improve traffic-light protocols for induced earthquakes and the regulation of operational injection activities

Energy of injection-induced seismicity predicted from in-situ experiments.

The ability to predict the magnitude of an earthquake caused by deep fluid injections is an important factor for assessing the safety of the reservoir storage and the seismic hazard. Here, we propose a new approach to evaluate the seismic energy released during fluid injection by integrating injection parameters, induced aseismic deformation, and the distance of earthquake sources from injection. We use data from ten injection experiments performed at a decameter scale into fault zones in limestone and shale formations. We observe that the seismic energy and the hydraulic energy similarly depend on the injected fluid volume (V), as they both scale as V3/2. They show, however, a large discrepancy, partly related to a large aseismic deformation. Therefore, to accurately predict the released seismic energy, aseismic deformation should be considered in the budget through the residual deformation measured at the injection. Alternatively, the minimal hypocentral distance from injection points and the critical fluid pressure for fault reactivation can be used for a better prediction of the seismic moment in the total compilation of earthquakes observed during these experiments. Complementary to the prediction based only on the injected fluid volume, our approach opens the possibility of using alternative monitoring parameters to improve traffic-light protocols for induced earthquakes and the regulation of operational injection activities