A5040857813- Landslides and related hazards
- Granular flow and fluidized beds
- Solar and Space Plasma Dynamics
- earthquake and tectonic studies
- Cryospheric studies and observations
- Seismic Waves and Analysis
- Seismology and Earthquake Studies
- Ionosphere and magnetosphere dynamics
- Seismic Imaging and Inversion Techniques
- Geotechnical and Geomechanical Engineering
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Geology and Paleoclimatology Research
- Geological formations and processes
- Hydrology and Sediment Transport Processes
- Computational Fluid Dynamics and Aerodynamics
- Winter Sports Injuries and Performance
- Astronomy and Astrophysical Research
- Climate change and permafrost
- Earthquake Detection and Analysis
- Image Processing and 3D Reconstruction
- Soil and Unsaturated Flow
- Rock Mechanics and Modeling
Institut de physique du globe de Paris
2016-2025
Institut Universitaire de France
2022-2025
Université Paris Cité
2015-2024
Centre National de la Recherche Scientifique
2015-2024
Institut national de recherche en informatique et en automatique
2014-2024
Sorbonne Université
2006-2024
Laboratoire Jacques-Louis Lions
2015-2024
Sorbonne Paris Cité
2012-2023
ESPCI Paris
2023
Institut Langevin
2023
[1] Noise with periods 3 to 10 s, ubiquitous in seismic records, is expected be mostly generated by pairs of ocean wave trains opposing propagation directions half the frequency. Here we present first comprehensive numerical model microseismic generation random waves, including reflections. Synthetic and observed spectra are well correlated (r > 0.85). On basis results, noise events can clustered three broad classes: wind waves a directional spectrum (class I), sea states significant...
We describe laboratory experiments of granular material flowing over an inclined plane covered by erodible bed, designed to mimic erosion processes natural flows travelling deposits built up earlier events. Two controlling parameters are the inclination and thickness layer. show that can increase flow mobility (i.e., runout) slopes with close repose angle grains θ r 40%, even for very thin beds. Erosion efficiency is shown strongly depend on slope topography. Entrainment begins affect at...
Research Article| November 19, 2013 An Automatic Kurtosis‐Based P‐ and S‐Phase Picker Designed for Local Seismic Networks Christian Baillard; Baillard aUniversité Paris Diderot–PRES Sorbonne Cité, Institut de Physique du Globe Paris, UMR CNRS 7154, 1 rue Jussieu, 75238 Francebaillard@ipgp.frcrawford@ipgp.frhibert@ipgp.frmangeney@ipgp.fr Search other works by this author on: GSW Google Scholar Wayne C. Crawford; Crawford Valérie Ballu; Ballu bUniversité La Rochelle, Littoral, Environnement et...
This review article provides an overview of dry granular flows and particle fluid mixtures, including experimental numerical modeling at the laboratory scale, large scale hydrodynamics approaches field observations. Over past ten years, theoretical have made such significant progress that they are capable providing qualitative quantitative estimates concentration velocity profiles in steady fully developed particulate flows. The next step which is currently extension these to unsteady...
Climate change is increasingly predisposing polar regions to large landslides. Tsunamigenic landslides have occurred recently in Greenland ( Kalaallit Nunaat ), but none been reported from the eastern fjords. In September 2023, we detected start of a 9-day-long, global 10.88-millihertz (92-second) monochromatic very-long-period (VLP) seismic signal, originating East Greenland. this study, demonstrate how event started with glacial thinning–induced rock-ice avalanche 25 × 10 6 cubic meters...
The transient surface flow occurring when a cylindrical pile of dry granular material is suddenly allowed to spread on horizontal plane investigated experimentally as function the released mass M, initial aspect ratio cylinder pile, properties underlying substrate (smooth or rough, rigid erodible) and bead size. Two different regimes leading three deposit morphologies are observed a, whatever For a≲3, spreads through an avalanche its flanks producing either truncated cone conical deposits....
Cliff collapse is an active geomorphological process acting at the surface of Earth and telluric planets. Recent laboratory studies have investigated initially cylindrical granular mass along a rough horizontal plane for different initial aspect ratios = H i / R , where are height radius, respectively. A numerical simulation these experiments performed using minimal depth‐integrated model based on long‐wave approximation. dimensional analysis equations shows that such exhibits scaling laws...
Numerical modeling of debris avalanche is presented here. The model uses the long‐wave approximation based on small aspect ratio avalanches as in classical Saint Venant shallow water. Depth‐averaged equations using this are derived a reference frame linked to topography. Debris treated here single‐phase, dry granular flow with Coulomb‐type behavior. numerical finite volume method kinetic scheme description microscopic behavior system define fluxes at interfaces element mesh. main advantage...
When not laterally confined in valleys, pyroclastic flows create their own channel along the slope by selecting a given flowing width. Furthermore, lobe‐shaped deposits display very specific morphology with high parallel lateral levees. A numerical model based on Saint Venant equations and empirical variable friction coefficient proposed Pouliquen Forterre (2002) is used to simulate unconfined granular flow over an inclined plane constant supply. Numerical simulations successfully reproduce...
The seismic signals of hundreds 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 signal features.Moreover, indirect observation via the they generate can provide useful data for studying volcanoes temporal variations their structure.An increase in number rockfall events volumes might be an indicator structural weakness deformation volcano with...
The description of the turbulent spectrum magnetic fluctuations in solar wind kinetic range scales is not yet completely established. Here, we perform a statistical study 100 spectra measured by STAFF instrument on Cluster mission, which allows us to resolve from ion down fraction electron scales, i.e., ∼102 km ∼300 m. We show that for k⊥ρe ∈ [0.03, 3] (which corresponds approximately frequency spacecraft frame f [3, 300] Hz), all observed can be described general law E(k⊥)∝k−8/3⊥exp (−...
The rock‐ice avalanche that occurred in 2005 on Mount Steller, Alaska and the resulting long period seismic waves have been simulated for different scenarios (i.e., flow histories), with without erosion processes taken into account. This 40–60 Mm 3 traveled about 10 km down slope, mainly top of a glacier, eroding significant amount ice. It was recorded by 7 broadband stations. simulations were compared signal inverted history. results show that, when are account, reproduce observed at all...
Recent gullies on Mars are suspected to be the result of liquid‐water‐bearing flows. A formation from wet flows has been challenged by studies invoking granular (dry) Our study focuses sinuous shapes observed for some recent Martian gullies. Sinuous found in locations and slopes (of 10°–15°) similar straight gullies, they therefore related same processes. Numerical simulations performed here introducing topographic variations such as obstacles, roughness, or slope changes that could possibly...
The Thurwieser landslide that occurred in Italy 2004 and the seismic waves it generated have been simulated compared to signal recorded a few tens of kilometers from source (i.e., landquake). main features low frequency are reproduced by simulation. Topography effects on flowing mass major impact whereas they weakly affect low‐frequency wave propagation. Simulation makes possible discriminate between alternative scenarios for flow dynamics provide first estimates rheological parameters...
Entrainment of underlying debris by geophysical flows can significantly increase the flow deposit extent. To study this phenomenon, analog laboratory experiments have been conducted on granular column collapse over an inclined channel with and without erodible bed made similar material. Results show that for slope angles below a critical value θc, between 10° 16°, run out distance rf depends only initial height h0 is unaffected presence bed. On steeper slopes, dynamics change fundamentally,...
Since the collapse of Dolomieu crater floor at Piton de la Fournaise Volcano (la Réunion) in 2007, hundreds seismic signals generated by rockfalls have been recorded daily Observatoire Volcanologique du (OVPF). To study rockfall activity over a long period time, automated methods are required to process available continuous records. We present set designed identify, locate, and estimate volume from their signals. The method used automatically discriminate other common events OVPF is based on...
The strongest seismic noise, called secondary microseisms, is generated by ocean wave interactions and we model this noise using the theory of Longuet-Higgins generalized to random gravity waves. Noise sources are computed with an that takes into account coastal reflections. Variations source locations consistent seasonal variations spectra. spectra modelled over many years for stations representative various environments such as continent, island polar area constrain, each environment,...
Abstract. The time domain sampler (TDS) experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near Lagrange point L1. In range of frequencies above proton plasma frequency fpi smaller than or order electron fpe, TDS observed three kinds electrostatic (e.s.) waves: coherent packets Langmuir waves f ~ ion acoustic < more less isolated non-sinusoidal spikes lasting 1 ms....
Kinetic 1D simulations reveal that a weak density depression in current-carrying plasma can lead to the formation of strong potential ramp (double layer). The and turbulence it creates share many features with recent particle field measurements auroral ionosphere. An electron beam accelerated by produces series propagating phase-space holes via spatial two-stream instability. Electron heating associated merging these is found influence subsequent evolution ramp.