1IPGP - Institut de Physique du Globe de Paris (IPGP, 1 rue Jussieu, 75238 Paris cedex 05 ; Université Paris Diderot, Bât. Lamarck A case postale 7011, 75205 Paris CEDEX 13 - France)
2GR - Géosciences Rennes (Bâtiment 15 - Université de Rennes 1 - Campus de Beaulieu -263 Av du général Leclerc- CS 74205 - 35042 Rennes Cedex - France - France)
Abstract : This paper examines how the resolution of small-scale geological density models is improved through the fusion of information provided by gravity measurements and density muon radiographies. Muon radiography aims at determining the density of geological bodies by measuring their screening effect on the natural flux of cosmic muons. Muon radiography essentially works like a medical X-ray scan and integrates density information along elongated narrow conical volumes. Gravity measurements are linked to density by a 3-D integration encompassing the whole studied domain. We establish the mathematical expressions of these integration formulas - called acquisition kernels - and derive the resolving kernels that are spatial filters relating the true unknown density structure to the density distribution actually recovered from the available data. The resolving kernel approach allows one to quantitatively describe the improvement of the resolution of the density models achieved by merging gravity data and muon radiographies. The method developed in this paper may be used to optimally design the geometry of the field measurements to be performed in order to obtain a given spatial resolution pattern of the density model to be constructed. The resolving kernels derived in the joined muon-gravimetry case indicate that gravity data are almost useless for constraining the density structure in regions sampled by more than two muon tomography acquisitions. Interestingly, the resolution in deeper regions not sampled by muon tomography is significantly improved by joining the two techniques. The method is illustrated with examples for the La Soufrière volcano of Guadeloupe.
https://hal-insu.archives-ouvertes.fr/insu-03579527 Contributor : Isabelle DubigeonConnect in order to contact the contributor Submitted on : Friday, February 18, 2022 - 11:13:58 AM Last modification on : Thursday, June 2, 2022 - 2:48:15 PM Long-term archiving on: : Thursday, May 19, 2022 - 6:39:27 PM
Kevin Jourde, Dominique Gibert, Jacques Marteau. Improvement of density models of geological structures by fusion of gravity data and cosmic muon radiographies. Geoscientific Instrumentation, Methods and Data Systems, European Geosciences Union 2015, 4, pp.177-188. ⟨10.5194/gi-4-177-2015⟩. ⟨insu-03579527⟩