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A gravimetric assessment of the Gotthard Base Tunnel geological model: insights from a novel gravity terrain-adaptation correction and rock physics data
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SYSNO ASEP 0564309 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název A gravimetric assessment of the Gotthard Base Tunnel geological model: insights from a novel gravity terrain-adaptation correction and rock physics data Tvůrce(i) Scarponi, Matteo (GFU-E) ORCID
Hetényi, G. (CH)
Baron, L. (CH)
Marti, U. (CH)Číslo článku 22 Zdroj.dok. Swiss Journal of Geosciences - ISSN 1661-8726
Roč. 115, č. 1 (2022)Poč.str. 21 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. CH - Švýcarsko Klíč. slova Gotthard Base Tunnel ; gravity modelling ; geological model ; Central Alps ; relative gravity measurements ; density-dependent terrain-adaptation correction Obor OECD Volcanology Způsob publikování Open access Institucionální podpora GFU-E - RVO:67985530 UT WOS 000881998000001 EID SCOPUS 85141848505 DOI 10.1186/s00015-022-00422-z Anotace The Gotthard Base Tunnel (GBT) is a 57 km long railway tunnel, constructed in the Central Alps in Switzerland and extending mainly North-South across numerous geological units. We acquired 80 new gravity data points at the surface along the GBT profile and used 77 gravity measurements in the tunnel to test and constrain the shallow crustal, km-scale geological model established during the tunnel construction. To this end, we developed a novel processing scheme, which computes a fully 3D, density-dependent gravity terrain-adaptation correction (TAC), to consistently compare the gravity observations with the 2D geological model structure, the latter converted into a density model. This approach allowed to explore and quantify candidate rock density distributions along the GBT modelled profile in a computationally-efficient manner, and to test whether a reasonable fit can be found without structural modification of the geological model. The tested density data for the various lithologies were compiled from the SAPHYR rock physical property database. The tested models were evaluated both in terms of misfit between observed and synthetic gravity data, and also in terms of correlation between misfit trend and topography of the target profile. The results indicate that the locally sampled densities provide a better fit to the data for the considered lithologies, rather than density data averaged over a wider set of Alpine rock samples for the same lithology. Furthermore, using one homogeneous and constant density value for all the topographic corrections does not provide an optimal fit to the data, which instead confirms density variations along the profile. Structurally, a satisfactory fit could be found without modifying the 2D geological model, which thus can be considered gravimetry-proof. From a more general perspective, the gravity data processing routines and the density-dependent corrections developed in this case study represent a remarkable potential for further high-resolution gravity investigations of geological structures. Pracoviště Geofyzikální ústav Kontakt Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Rok sběru 2023 Elektronická adresa https://link.springer.com/article/10.1186/s00015-022-00422-z
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