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6 results on '"Stutzmann É"'

1. Modelling iceberg capsize in the open ocean

Author

Bonnet, P., Yastrebov, V. A., Queutey, P., Leroyer, A., Mangeney, A., Castelnau, O., Sergeant, A., Stutzmann, E., and Montagner, J. -P.

Subjects
Physics - Fluid Dynamics, Physics - Geophysics
Abstract

At near-grounded glacier termini, calving can lead to the capsize of kilometer-scale unstable icebergs. The transient contact force applied by the capsizing iceberg on the glacier front generates seismic waves that propagate over teleseismic distances. The inversion of this seismic signal is of great interest to get insight into actual and past capsize dynamics. However, the iceberg size, which is of interest for geophysical and climatic studies, cannot be recovered from the seismic amplitude alone. This is because the capsize is a complex process involving interactions between the iceberg, the glacier and the surrounding water. This paper presents a first step towards the construction of a complete model, and is focused on the capsize in the open ocean without glacier front nor ice-m\'elange. The capsize dynamics of an iceberg in the open ocean is captured by computational fluid dynamics (CFD) simulations, which allows assessing the complexity of the fluid motion around a capsizing iceberg and how far the ocean is affected by iceberg rotation. Expressing the results in terms of appropriate dimensionless variables, we show that laboratory scale and field scale capsizes can be directly compared. The capsize dynamics is found to be highly sensitive to the iceberg aspect ratio and to the water and ice densities. However, dealing at the same time with the fluid dynamics and the contact between the iceberg and the deformable glacier front requires highly complex coupling that often goes beyond actual capabilities of fluid-structure interaction softwares. Therefore, we developed a semi-analytical simplified fluid-structure model (SAFIM) that can be implemented in solid mechanics computations dealing with contact dynamics of deformable solids. This model accounts for hydrodynamic forces through calibrated drag and added-mass effects, and is calibrated against the reference CFD simulations..., Comment: 31 pages, 16 figures

Published
2020

2. MSS/1: Single-Station and Single-Event Marsquake Inversion

Author

Drilleau, M, Drilleau, M, Beucler, É, Lognonné, P, Panning, MP, Knapmeyer-Endrun, B, Banerdt, WB, Beghein, C, Ceylan, S, van Driel, M, Joshi, R, Kawamura, T, Khan, A, Menina, S, Rivoldini, A, Samuel, H, Stähler, S, Xu, H, Bonnin, M, Clinton, J, Giardini, D, Kenda, B, Lekic, V, Mocquet, A, Murdoch, N, Schimmel, M, Smrekar, SE, Stutzmann, É, Tauzin, B, Tharimena, S, Drilleau, M, Drilleau, M, Beucler, É, Lognonné, P, Panning, MP, Knapmeyer-Endrun, B, Banerdt, WB, Beghein, C, Ceylan, S, van Driel, M, Joshi, R, Kawamura, T, Khan, A, Menina, S, Rivoldini, A, Samuel, H, Stähler, S, Xu, H, Bonnin, M, Clinton, J, Giardini, D, Kenda, B, Lekic, V, Mocquet, A, Murdoch, N, Schimmel, M, Smrekar, SE, Stutzmann, É, Tauzin, B, and Tharimena, S

Abstract

SEIS, the seismometer of the InSight mission, which landed on Mars on 26 November 2018, is monitoring the seismic activity of the planet. The goal of the Mars Structure Service (MSS) is to provide, as a mission product, the first average 1-D velocity model of Mars from the recorded InSight data. Prior to the mission, methodologies have been developed and tested to allow the location of the seismic events and estimation of the radial structure, using surface waves and body waves arrival times, and receiver functions. The paper describes these validation tests and compares the performance of the different algorithms to constrain the velocity model below the InSight station and estimate the 1-D average model over the great circle path between source and receiver. These tests were performed in the frame of a blind test, during which synthetic data were inverted. In order to propagate the data uncertainties on the output model distribution, Bayesian inversion techniques are mainly used. The limitations and strengths of the methods are assessed. The results show the potential of the MSS approach to retrieve the structure of the crust and underlying mantle. However, at this time, large quakes with clear surface waves have not yet been recorded by SEIS, which makes the estimation of the 1-D average seismic velocity model challenging. Additional locatable events, especially at large epicentral distances, and development of new techniques to fully investigate the data, will ultimately provide more constraints on the crust and mantle of Mars.

Published
2020

5. Seismic detection of the martian core.

Author

Stähler SC, Khan A, Banerdt WB, Lognonné P, Giardini D, Ceylan S, Drilleau M, Duran AC, Garcia RF, Huang Q, Kim D, Lekic V, Samuel H, Schimmel M, Schmerr N, Sollberger D, Stutzmann É, Xu Z, Antonangeli D, Charalambous C, Davis PM, Irving JCE, Kawamura T, Knapmeyer M, Maguire R, Marusiak AG, Panning MP, Perrin C, Plesa AC, Rivoldini A, Schmelzbach C, Zenhäusern G, Beucler É, Clinton J, Dahmen N, van Driel M, Gudkova T, Horleston A, Pike WT, Plasman M, and Smrekar SE

Abstract

Clues to a planet's geologic history are contained in its interior structure, particularly its core. We detected reflections of seismic waves from the core-mantle boundary of Mars using InSight seismic data and inverted these together with geodetic data to constrain the radius of the liquid metal core to 1830 ± 40 kilometers. The large core implies a martian mantle mineralogically similar to the terrestrial upper mantle and transition zone but differing from Earth by not having a bridgmanite-dominated lower mantle. We inferred a mean core density of 5.7 to 6.3 grams per cubic centimeter, which requires a substantial complement of light elements dissolved in the iron-nickel core. The seismic core shadow as seen from InSight's location covers half the surface of Mars, including the majority of potentially active regions-e.g., Tharsis-possibly limiting the number of detectable marsquakes., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Published
2021
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6. Thickness and structure of the martian crust from InSight seismic data.

Author

Knapmeyer-Endrun B, Panning MP, Bissig F, Joshi R, Khan A, Kim D, Lekić V, Tauzin B, Tharimena S, Plasman M, Compaire N, Garcia RF, Margerin L, Schimmel M, Stutzmann É, Schmerr N, Bozdağ E, Plesa AC, Wieczorek MA, Broquet A, Antonangeli D, McLennan SM, Samuel H, Michaut C, Pan L, Smrekar SE, Johnson CL, Brinkman N, Mittelholz A, Rivoldini A, Davis PM, Lognonné P, Pinot B, Scholz JR, Stähler S, Knapmeyer M, van Driel M, Giardini D, and Banerdt WB

Abstract

A planet's crust bears witness to the history of planetary formation and evolution, but for Mars, no absolute measurement of crustal thickness has been available. Here, we determine the structure of the crust beneath the InSight landing site on Mars using both marsquake recordings and the ambient wavefield. By analyzing seismic phases that are reflected and converted at subsurface interfaces, we find that the observations are consistent with models with at least two and possibly three interfaces. If the second interface is the boundary of the crust, the thickness is 20 ± 5 kilometers, whereas if the third interface is the boundary, the thickness is 39 ± 8 kilometers. Global maps of gravity and topography allow extrapolation of this point measurement to the whole planet, showing that the average thickness of the martian crust lies between 24 and 72 kilometers. Independent bulk composition and geodynamic constraints show that the thicker model is consistent with the abundances of crustal heat-producing elements observed for the shallow surface, whereas the thinner model requires greater concentration at depth., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Published
2021
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