Identifying subarctic river thermal and mechanical ice break-up using seismic sensing
River-ice break-up in high-latitude regions, despite its brevity, is a fundamental process, representing the most dynamic and complex period of fluvial processes. Moreover, ice break-up has significant cascading ecological effects, with a different severity for mechanical vs. thermal break-up, and t...
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Umeå universitet, Institutionen för ekologi, miljö och geovetenskap
2021
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ftumeauniv:oai:DiVA.org:umu-183992 2023-10-09T21:56:09+02:00 Identifying subarctic river thermal and mechanical ice break-up using seismic sensing Ursica, Stefania 2021 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-183992 eng eng Umeå universitet, Institutionen för ekologi, miljö och geovetenskap http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-183992 info:eu-repo/semantics/openAccess Ice break-up River ice Subarctic Thermal melting Mechanical break-up Freeze-up Environmental seismology Seismic signals Earth and Related Environmental Sciences Geovetenskap och miljövetenskap Student thesis info:eu-repo/semantics/bachelorThesis text 2021 ftumeauniv 2023-09-22T13:53:58Z River-ice break-up in high-latitude regions, despite its brevity, is a fundamental process, representing the most dynamic and complex period of fluvial processes. Moreover, ice break-up has significant cascading ecological effects, with a different severity for mechanical vs. thermal break-up, and thus, motivates the importance of monitoring efforts. Classical research methods, such as fieldwork or analysis of photographs and aerial imagery, offer a general perspective on the timing of ice break-up but have safety and logistic issues caused by the dangers of unstable ice cover, the lag times between event occurrence and observation, and the frequent low visibilities. The emerging field of environmental seismology, which studies surface processes through seismic signals, provides an alternative solution to these shortcomings by continuously recording high temporal resolution data. Seismic sensing can potentially record any event within a set distance if the produced signal is powerful enough. Three geophones had monitored the subarctic Sävar River reach for 185 days to test the efficiency of seismic methods to capture ice-cracking events, and based on their characteristics, to identify thermal vs. mechanical ice break-up. With visual and multivariate analysis, seismic methods provided a conservative set of 2 228 events, detected at milliseconds precision, described, and located. Besides, both trigger lag times and principal component analysis depicted correlations between environmental drivers and ice-cracking events. The automatic picker based on duration and trigger thresholds required manual supervision because of the initial numerous false signals that accounted for 96% of total initial events. Ice-cracking signals as short as 0.2s and frequencies of 8-40 Hz with an average power of -117 dB were statistically defined, classified, and described by case events as two types, associated, based on their spectral and temporal patterns, with the two ice break-up modes. With an estimated Rayleigh wave velocity of 680 ... Bachelor Thesis Subarctic Umeå University: Publications (DiVA) |
institution |
Open Polar |
collection |
Umeå University: Publications (DiVA) |
op_collection_id |
ftumeauniv |
language |
English |
topic |
Ice break-up River ice Subarctic Thermal melting Mechanical break-up Freeze-up Environmental seismology Seismic signals Earth and Related Environmental Sciences Geovetenskap och miljövetenskap |
spellingShingle |
Ice break-up River ice Subarctic Thermal melting Mechanical break-up Freeze-up Environmental seismology Seismic signals Earth and Related Environmental Sciences Geovetenskap och miljövetenskap Ursica, Stefania Identifying subarctic river thermal and mechanical ice break-up using seismic sensing |
topic_facet |
Ice break-up River ice Subarctic Thermal melting Mechanical break-up Freeze-up Environmental seismology Seismic signals Earth and Related Environmental Sciences Geovetenskap och miljövetenskap |
description |
River-ice break-up in high-latitude regions, despite its brevity, is a fundamental process, representing the most dynamic and complex period of fluvial processes. Moreover, ice break-up has significant cascading ecological effects, with a different severity for mechanical vs. thermal break-up, and thus, motivates the importance of monitoring efforts. Classical research methods, such as fieldwork or analysis of photographs and aerial imagery, offer a general perspective on the timing of ice break-up but have safety and logistic issues caused by the dangers of unstable ice cover, the lag times between event occurrence and observation, and the frequent low visibilities. The emerging field of environmental seismology, which studies surface processes through seismic signals, provides an alternative solution to these shortcomings by continuously recording high temporal resolution data. Seismic sensing can potentially record any event within a set distance if the produced signal is powerful enough. Three geophones had monitored the subarctic Sävar River reach for 185 days to test the efficiency of seismic methods to capture ice-cracking events, and based on their characteristics, to identify thermal vs. mechanical ice break-up. With visual and multivariate analysis, seismic methods provided a conservative set of 2 228 events, detected at milliseconds precision, described, and located. Besides, both trigger lag times and principal component analysis depicted correlations between environmental drivers and ice-cracking events. The automatic picker based on duration and trigger thresholds required manual supervision because of the initial numerous false signals that accounted for 96% of total initial events. Ice-cracking signals as short as 0.2s and frequencies of 8-40 Hz with an average power of -117 dB were statistically defined, classified, and described by case events as two types, associated, based on their spectral and temporal patterns, with the two ice break-up modes. With an estimated Rayleigh wave velocity of 680 ... |
format |
Bachelor Thesis |
author |
Ursica, Stefania |
author_facet |
Ursica, Stefania |
author_sort |
Ursica, Stefania |
title |
Identifying subarctic river thermal and mechanical ice break-up using seismic sensing |
title_short |
Identifying subarctic river thermal and mechanical ice break-up using seismic sensing |
title_full |
Identifying subarctic river thermal and mechanical ice break-up using seismic sensing |
title_fullStr |
Identifying subarctic river thermal and mechanical ice break-up using seismic sensing |
title_full_unstemmed |
Identifying subarctic river thermal and mechanical ice break-up using seismic sensing |
title_sort |
identifying subarctic river thermal and mechanical ice break-up using seismic sensing |
publisher |
Umeå universitet, Institutionen för ekologi, miljö och geovetenskap |
publishDate |
2021 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-183992 |
genre |
Subarctic |
genre_facet |
Subarctic |
op_relation |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-183992 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1779320668131688448 |