André Mangeney

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Numerical simulation can provide a useful tool for investigating the dynamics of phenomena like rock avalanches, within realistic geological contexts and in the framework of a better risk assessment and decision making. Difficulties in numerical modelling of a heterogeneous moving mass are mainly linked to the simulation of the complex behaviour assumed by(More)
This paper reports a two-dimensional hybrid simulation study which utilizes an expanding box model to represent the slow compression of the plasma as it flows through the magnetosheath. In the code we model the compression as an external force: The physical sizes of the simulation box decrease with time. We present results of a simulation which starts in a(More)
We study the evolution of the expanding solar wind using a one-dimensional and a two-dimensional expanding box model [Grap-pin et al., 1993] implemented here within a hybrid code [Liewer et al., 2001]. We first consider a plasma with protons and 5 % of alpha particles, without drift between the protons and alphas, considering successively the low-beta and(More)
[1] The seismic signals of hundreds of rockfalls within Dolomieu crater, Piton de la Fournaise volcano, Réunion Island, have been analyzed to investigate a possible link between physical rockfall-generating processes and associated seismic signal features. Moreover, indirect observation of rockfalls via the seismic signals they generate can provide useful(More)
We present a numerical scheme for the integration of the Vlasov–Maxwell system of equations for a non-relativistic plasma, in the hybrid approximation, where the Vlasov equation is solved for the ion distribution function and the electrons are treated as a fluid. In the Ohm equation for the electric field, effects of electron inertia have been retained, in(More)
Key Points: • New seismology-based method for the identification of rockfalls • New method for the picking of the rockfall seismic signals emergent onsets • New seismology-based method for the location of rockfalls Abstract Since the collapse of the Dolomieu crater floor at Piton de la Fournaise Volcano (la Réunion) in 2007, hundreds of seismic signals(More)
Ground failures, caving processes and collapses of large natural or man-made underground cavities can produce significant socioeconomic damages and represent a serious risk envisaged by the mine managements and municipalities. In order to improve our understanding of the mechanisms governing such a geohazard and to test the potential of geophysical methods(More)
A new tool, Hybrid Expanding Box (HEB) model is presented and applied to study wave-particle interactions in collisionless plasmas in two cases. First, the HEB code is used to investigate the effect of a slow compression on protons in the magnetosheath. The simulation results verify the hypothesis of the magnetosheath marginal stability path with respect to(More)
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