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dc.contributor.author
Hellmann, Sebastian
dc.contributor.author
Grab, Melchior
dc.contributor.author
Patzer, Cedric
dc.contributor.author
Bauder, Andreas
dc.contributor.author
Maurer, Hansruedi
dc.date.accessioned
2023-04-06T11:32:40Z
dc.date.available
2023-01-19T12:49:35Z
dc.date.available
2023-03-27T13:02:15Z
dc.date.available
2023-04-06T11:32:40Z
dc.date.issued
2022-10-17
dc.identifier.other
10.5194/egusphere-2022-1069
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/593602
dc.identifier.doi
10.3929/ethz-b-000593602
dc.description.abstract
Cross-borehole seismic tomography is a powerful tool to investigate the subsurface with a very high spatial resolution. In a set of boreholes, comprehensive three-dimensional investigations at different depths can be obtained to analyse velocity anisotropy effects due to local changes within the medium. Especially in glaciological applications, the drilling of boreholes with hot water is cost-efficient and provides rapid access to the internal structure of the ice. In turn, movements of the subsurface such as the continuous flow of ice masses cause deformations of the boreholes and exacerbate a precise determination of the source and receiver positions along the borehole trajectories. Here, we present a three-dimensional inversion scheme that considers the deviations of the boreholes as additional model parameters next to the common velocity inversion parameters. Instead of introducing individual parameters for each source and receiver position, we describe the borehole trajectory with two orthogonal polynomials and only invert for the polynomial coefficients. This significantly reduces the number of additional model parameters and leads to much more stable inversion results. In addition, we also discuss whether the inversion of the borehole parameters can be separated from the velocity inversion, which would enhance the flexibility of our inversion scheme. In that case, updates of the borehole trajectories are only performed if this further reduces the overall error in the data sets. We apply this sequential inversion scheme on a synthetic data set and a field data set from a temperate Alpine glacier. With the sequential inversion, the number of artefacts in the velocity model decreases compared to a velocity inversion without borehole adjustments and heterogeneities in the velocity model can be imaged similar to an inversion with correct borehole coordinates. Furthermore, we discuss the advantages and limitations of our approach in the context of an inherent seismic anisotropy of the medium and extend our algorithm to consider an elliptic velocity anisotropy. With this extended version of the algorithm, we analyse the interference between a seismic anisotropy in the medium and the borehole coordinate adjustment. Our analysis indicates that the borehole inversion interferes with seismic velocity anisotropy. The inversion can compensate such a velocity anisotropy. Therefore, for such a borehole trajectory inversion, polynomials of degree three are a good compromise between a good representation of the true borehole trajectories and avoiding compensation for velocity anisotropy.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Copernicus
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/4.0/
dc.title
A borehole trajectory inversion scheme to adjust the measurement geometry for 3D travel time tomography on glaciers
en_US
dc.type
Working Paper
dc.rights.license
Creative Commons Attribution 4.0 International
ethz.journal.title
EGUsphere
ethz.size
29 p.
en_US
ethz.grant
Comprehensive 3D characterization of temperate alpine glaciers using geophysical techniques
en_US
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02330 - Dep. Erdwissenschaften / Dep. of Earth Sciences::02506 - Institut für Geophysik / Institute of Geophysics::03953 - Robertsson, Johan / Robertsson, Johan
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02330 - Dep. Erdwissenschaften / Dep. of Earth Sciences::02506 - Institut für Geophysik / Institute of Geophysics::03953 - Robertsson, Johan / Robertsson, Johan
en_US
ethz.grant.agreementno
169329
ethz.grant.agreementno
169329
ethz.grant.agreementno
169329
ethz.grant.fundername
SNF
ethz.grant.fundername
SNF
ethz.grant.fundername
SNF
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.program
Projekte MINT
ethz.grant.program
Projekte MINT
ethz.grant.program
Projekte MINT
ethz.relation.isSupplementedBy
10.3929/ethz-b-000541812
ethz.relation.isPreviousVersionOf
10.3929/ethz-b-000625346
ethz.date.deposited
2023-01-19T12:49:36Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2023-03-27T13:02:17Z
ethz.rosetta.lastUpdated
2024-02-02T21:32:20Z
ethz.rosetta.versionExported
true
ethz.COinS
ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.atitle=A%20borehole%20trajectory%20inversion%20scheme%20to%20adjust%20the%20measurement%20geometry%20for%203D%20travel%20time%20tomography%20on%20glaciers&rft.jtitle=EGUsphere&rft.date=2022-10-17&rft.au=Hellmann,%20Sebastian&Grab,%20Melchior&Patzer,%20Cedric&Bauder,%20Andreas&Maurer,%20Hansruedi&rft.genre=preprint&rft_id=info:doi/10.5194/egusphere-2022-1069&
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