dc.contributor.advisor | Hanssen, Alfred | |
dc.contributor.author | Romeyn, Rowan | |
dc.date.accessioned | 2022-03-09T11:13:59Z | |
dc.date.available | 2022-03-09T11:13:59Z | |
dc.date.issued | 2022-03-22 | |
dc.description.abstract | The 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.doctoraltype | ph.d. | en_US |
dc.description.popularabstract | The 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.sponsorship | This 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.isbn | 978-82-8236-472-0 | |
dc.identifier.uri | https://hdl.handle.net/10037/24344 | |
dc.language.iso | eng | en_US |
dc.publisher | UiT Norges arktiske universitet | en_US |
dc.publisher | UiT The Arctic University of Norway | en_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.accessRights | openAccess | en_US |
dc.rights.holder | Copyright 2022 The Author(s) | |
dc.rights.uri | https://creativecommons.org/licenses/by-nc-sa/4.0 | en_US |
dc.rights | Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) | en_US |
dc.subject | VDP::Mathematics and natural science: 400::Geosciences: 450::Other geosciences: 469 | en_US |
dc.subject | VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Andre geofag: 469 | en_US |
dc.subject | geophysics | en_US |
dc.subject | geofysikk | en_US |
dc.subject | seismology | en_US |
dc.subject | seismologi | en_US |
dc.subject | cryosphere | en_US |
dc.subject | permafrost | en_US |
dc.subject | dynamical model | en_US |
dc.subject | seismic wave | en_US |
dc.subject | frost quake | en_US |
dc.subject | ice quake | en_US |
dc.subject | thermal stress | en_US |
dc.subject | sea ice | en_US |
dc.subject | passive seismic | en_US |
dc.subject | dispersion | en_US |
dc.subject | beamforming | en_US |
dc.subject | frozen ground | en_US |
dc.subject | Svalbard | en_US |
dc.subject | environmental seismology | en_US |
dc.subject | cryoseismology | en_US |
dc.subject | elastic properties | en_US |
dc.subject | viscoelastic | en_US |
dc.subject | thermoviscoelastic | en_US |
dc.subject | surface wave | en_US |
dc.subject | guided wave | en_US |
dc.subject | thermal contraction | en_US |
dc.subject | frost creep | en_US |
dc.subject | rheology | en_US |
dc.subject | Van Mijenfjorden | en_US |
dc.subject | Adventdalen | en_US |
dc.subject | air-coupled flexural wave | en_US |
dc.subject | ice thickness | en_US |
dc.subject | periglacial | en_US |
dc.title | Cracking into Cryoseismology | en_US |
dc.type | Doctoral thesis | en_US |
dc.type | Doktorgradsavhandling | en_US |