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Introduction of absolute gravimetric techniques into a high-precision gracity and vertical control system in Northern Iceland / Wolfgang Torge (1992)

Public Titre : Introduction of absolute gravimetric techniques into a high-precision gracity and vertical control system in Northern Iceland Type de document : Monographie Auteurs : Wolfgang Torge, Auteur ; T. Grote, Auteur ; R.H. Roder, Auteur ; M. Schnull, Auteur ; H.G. Wenzel, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 1992 Collection : DGK - B Sous-collection : Angewandte Geodäsie num. 297 Importance : 52 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-8581-7 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] déformation verticale de la croute terrestre [Termes IGN] gravimètre absolu [Termes IGN] Islande [Termes IGN] réseau altimétrique local [Termes IGN] réseau gravimétrique [Termes IGN] système de référence géodésique [Termes IGN] volcan Index. décimale : 30.43 Travaux de géodésie physique Résumé : (Auteur) Since 1938 gravity measurements were carried out in northern Iceland to investigate the tectonic process connected with the diverging of the Eurasian and the North American Plate. This paper describes the measurements performed by Institut für Erdmessung, Universität Hannover in 1985 and 1987/88. In the last epoch 1987/88, the absolute gravimeter JILAG-3 was first employed in order to contribute to the gravimetric datum and to overcome the calibration problem being inherent to the relative gravimetric technique. The detail survey in 1985 and 1987 was carried out using four to six LaCoste&Romberg gravimeters. By establishing four absolute stations in the control area in northern Iceland, and one in Reykjavik, the absolute gravity datum and the linear calibration could be verified on the 0.05 to 0.1 µms-2 and the 1-10-4 level, respectively. The mean relative network accuracy in 1985 (with respect to a constrained base station) and the mean absolute accuracy in 1987/88 is estimated to be ±0.06 /µms-2. As in former surveys, gravimetry was supplemented by geometric leveling. The tectonic activity in the Krafia fissure zone of northern Iceland has remarkably decreased in the beginning of the 1980's. The results of the 1985 and 1987/88 surveys indicate that the minor tectonic event which occurred in 1984 together with lava outflow, caused small variations with a range of about 20 km around the Krafia central volcano, reaching maximum changes of 0.4 µms-2 in gravity and 0.2 m in height compared to the 1980/81 surveys. The general tendency, gravity increase and subsidence in the activity center (Namafjall/Krafla area), and correlated gravity decrease and uplift at the flanks, is still visible. Numéro de notice : 30656 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=56853

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
30656-01	30.43	Livre	Centre de documentation	Géodésie	Disponible