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dc.contributor.advisorHanssen, Alfred
dc.contributor.authorRomeyn, Rowan
dc.date.accessioned2022-03-09T11:13:59Z
dc.date.available2022-03-09T11:13:59Z
dc.date.issued2022-03-22
dc.description.abstractThe cryosphere encompasses the seasonally and perennially frozen parts of the earth and its extent is both sensitive to and impacts upon the global climate through surface energy and moisture fluxes and feedbacks. The dynamics of ice and frozen ground also impact directly on, e.g., construction and maintenance of roads in cold regions or transportation across floating ice sheets. The aim of this thesis was to investigate the extent to which seismic methods can be used to study dynamic processes and longer-term changes in the cryosphere. The thesis is structured around three case studies linking active- and passive-source seismic experiments with numerical models of thermal stress, seismic wave dispersion and propagation. In Paper 1, temporary arrays of geophones with fine spatial sampling demonstrated that high ground-ice content in the near-surface during winter/spring produces a seasonally varying multimodal surface wave dispersion pattern. In Paper 2, the role of thermal stress in triggering frost quakes was further explored using borehole temperature measurements and multi-decadal continuous seismic recordings from the small-aperture Spitsbergen seismic array (SPITS). Thermal contraction cracking within the frozen active layer was shown to be a plausible mechanism contributing to frost quake seismicity. In Paper 3, a multi-annual catalogue of explosive source seismic experiments conducted on first-year sea-ice in Van Mijenfjorden, Svalbard, was used to demonstrate the usefulness of air-coupled flexural waves for estimating the thickness of a floating ice sheet. Viewed as a whole, the case studies developed in this thesis illustrate the ability of seismic methods to record and monitor dynamic processes in the cryosphere over a range of temporal scales. Continuous passive seismic recordings with high-temporal resolution provide a useful complement to other geophysical and remote sensing techniques used for monitoring the dynamics of the cryosphere.en_US
dc.description.doctoraltypeph.d.en_US
dc.description.popularabstractThe cryosphere groups the parts of the earth that are frozen either year-round or seasonally and contributes to global climate by, e.g., reflecting sunlight from snow and ice or releasing methane trapped in permafrost. The physical properties of the frozen parts of the earth also impacts directly on e.g., construction and maintenance of roads in cold regions or transportation across floating ice sheets. In this thesis we use geophones that measure seismic vibrations in the ground. We found that vibrations produced by thermal contraction stresses and cracks can be used to monitor variation in the stiffness of the ground. We also found that the frequency of sounds emitted by floating ice sheets can be used to estimate their thickness. This thesis demonstrates that measuring seismic vibrations gives useful insight into the physical properties and processes of ice and frozen ground and how they vary over seasonal to yearly timescales.en_US
dc.description.sponsorshipThis research has been funded by the University of Tromsø - The Arctic University of Norway, by the ARCEx partners and by the Research Council of Norway through grant number 228107. The publication charges for the research papers, that constitute an important contribution of this study, were covered by a series of grants from the publication fund of UiT - The Arctic University of Norway.en_US
dc.identifier.isbn978-82-8236-472-0
dc.identifier.urihttps://hdl.handle.net/10037/24344
dc.language.isoengen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.relation.haspart<p>Paper I: Romeyn, R., Hanssen, A., Ruud, B.O., Stemland, H.M. & Johansen, T.A. (2021). Passive seismic recording of cryoseisms in Adventdalen, Svalbard. <i>The Cryosphere, 15</i>, 283–302. Also available in Munin at <a href=https://hdl.handle.net/10037/20566> https://hdl.handle.net/10037/20566</a>. <p>Paper II: Romeyn, R., Hanssen, A. & Köhler, A. (2021). Long term analysis of cryoseismic events and associated ground thermal stress in Adventdalen, Svalbard. <i>The Cryosphere Discussions</i>, preprint, in review. Also available at <a href=https://doi.org/10.5194/tc-2021-329>https://doi.org/10.5194/tc-2021-329</a>. <p>Paper III: Romeyn, R., Hanssen, A., Ruud, B.O. & Johansen, T.A. (2021). Sea ice thickness from air-coupled flexural waves. <i>The Cryosphere, 15</i>, 2939–2955. Also available in Munin at <a href=https://hdl.handle.net/10037/21600>https://hdl.handle.net/10037/21600</a>.en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2022 The Author(s)
dc.rights.urihttps://creativecommons.org/licenses/by-nc-sa/4.0en_US
dc.rightsAttribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Other geosciences: 469en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Andre geofag: 469en_US
dc.subjectgeophysicsen_US
dc.subjectgeofysikken_US
dc.subjectseismologyen_US
dc.subjectseismologien_US
dc.subjectcryosphereen_US
dc.subjectpermafrosten_US
dc.subjectdynamical modelen_US
dc.subjectseismic waveen_US
dc.subjectfrost quakeen_US
dc.subjectice quakeen_US
dc.subjectthermal stressen_US
dc.subjectsea iceen_US
dc.subjectpassive seismicen_US
dc.subjectdispersionen_US
dc.subjectbeamformingen_US
dc.subjectfrozen grounden_US
dc.subjectSvalbarden_US
dc.subjectenvironmental seismologyen_US
dc.subjectcryoseismologyen_US
dc.subjectelastic propertiesen_US
dc.subjectviscoelasticen_US
dc.subjectthermoviscoelasticen_US
dc.subjectsurface waveen_US
dc.subjectguided waveen_US
dc.subjectthermal contractionen_US
dc.subjectfrost creepen_US
dc.subjectrheologyen_US
dc.subjectVan Mijenfjordenen_US
dc.subjectAdventdalenen_US
dc.subjectair-coupled flexural waveen_US
dc.subjectice thicknessen_US
dc.subjectperiglacialen_US
dc.titleCracking into Cryoseismologyen_US
dc.typeDoctoral thesisen_US
dc.typeDoktorgradsavhandlingen_US


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