Centre de documentation
scientifique

Global Earth structure recovery from state-of-the-art models of the Earth’s gravity field and additional geophysical Information / K. Hamayun (2014)  

Public Titre : Global Earth structure recovery from state-of-the-art models of the Earth’s gravity field and additional geophysical Information Type de document : Thèse/HDR Auteurs : K. Hamayun, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2014 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 85 Importance : 165 p. ISBN/ISSN/EAN : 978-94-6186-325-6 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] champ de pesanteur terrestre [Termes IGN] données CHAMP [Termes IGN] données géophysiques [Termes IGN] données GOCE [Termes IGN] données GRACE [Termes IGN] levé gravimétrique Résumé : (auteur) Currently, a tremendous improvement is observed in the accuracy and spatial resolution of global Earth’s gravity field models. This improvement is achieved due to using various new data, including those from satellite gravimetry missions (CHAMP, GRACE, and GOCE); terrestrial and airborne gravity data, as well as altimetry data. The new gravity field models can be applied, in particular, to improve our knowledge of the Earth’s interior structure. The aim of this study is to compile a global map of the Moho interface using a global gravity model and additional available information about the crust density structure. In our study, we use the gravity field model EIGEN-6C2 and the global crustal model CRUST1.0 derived from seismic data. In addition, we utilize seismic-based models of Moho as prior information: CRUST1.0 model, as well as the Crust07 model, which was derived by a fully non-linear inversion of fundamental mode surface waves. The observed gravity field contains nuisance signals from the topography and density heterogeneities related to bathymetry, ice, sediments, and other crustal components. Therefore, we model and sequentially subtract these signals by applying so-called stripping corrections. This results in crust-stripped gravity field quantities (gravity anomalies and gravity disturbances). In the course of research, we review different analytical, semi-analytical, and numerical forward modeling techniques to compute the gravitational attraction of a body. We also derive an analytical formula for the computation of gravitational potential generated by a polyhedral body having linearly varying density. We compute the correction to observed gravity field using the analytical methods in the vicinity of the body and using semi-analytical methods in the far zone. We demonstrate that the sequential correction of gravity disturbances and gravity anomalies for nuisance signals increases the correlation with the Moho depths. We use the corrected gravity field to find the global (mean) value for the crust-mantle density contrast using the Pearson’s correlation method. We use an empirical technique in which the absolute correlation between the Moho depth from CRUST 1.0 model and the updated crust stripped gravity disturbances/anomalies is minimized. The updated stripped gravity disturbances/anomalies are obtained by adding a contribution (attraction) related to the density contrast between the reference crust and the upper most mantle to stripped gravity disturbances/anomalies. [...] Numéro de notice : 14852 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.4233/uuid:f8f6d8cd-9a6e-4ad1-8152-8d164c1055c9 En ligne : https://doi.org/10.4233/uuid:f8f6d8cd-9a6e-4ad1-8152-8d164c1055c9 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75698