Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling
SUMMARY A network of seismometers has been installed on the Gugla rock glacier since October 2015 to estimate seismic velocity changes and detect microseismicity. These two processes are related to mechanical and structural variations occurring within the rock glacier. Seismic monitoring thus allows...
Published in: | Geophysical Journal International |
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Oxford University Press (OUP)
2020
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Online Access: | http://dx.doi.org/10.1093/gji/ggaa097 http://academic.oup.com/gji/advance-article-pdf/doi/10.1093/gji/ggaa097/32757348/ggaa097.pdf http://academic.oup.com/gji/article-pdf/221/3/1719/32960456/ggaa097.pdf |
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croxfordunivpr:10.1093/gji/ggaa097 2024-09-15T18:29:59+00:00 Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling Guillemot, Antoine Helmstetter, Agnès Larose, Éric Baillet, Laurent Garambois, Stéphane Mayoraz, Raphaël Delaloye, Reynald Labex UGA INSU,CNRS ANR 2020 http://dx.doi.org/10.1093/gji/ggaa097 http://academic.oup.com/gji/advance-article-pdf/doi/10.1093/gji/ggaa097/32757348/ggaa097.pdf http://academic.oup.com/gji/article-pdf/221/3/1719/32960456/ggaa097.pdf en eng Oxford University Press (OUP) https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model Geophysical Journal International volume 221, issue 3, page 1719-1735 ISSN 0956-540X 1365-246X journal-article 2020 croxfordunivpr https://doi.org/10.1093/gji/ggaa097 2024-09-03T04:12:40Z SUMMARY A network of seismometers has been installed on the Gugla rock glacier since October 2015 to estimate seismic velocity changes and detect microseismicity. These two processes are related to mechanical and structural variations occurring within the rock glacier. Seismic monitoring thus allows a better understanding of the dynamics of rock glaciers throughout the year. We observed seasonal variations in seismic wave velocity and microseismic activity over the 3 yr of the study. In the first part of our analysis, we used ambient noise correlations to compute daily changes of surface wave velocity. In winter, seismic wave velocities were higher, probably due to refreezing of the permafrost active layer and cooling of the uppermost permafrost layers, leading to increased overall rigidity of the medium. This assumption was verified using a seismic model of wave propagation that estimates the depth of P- and S-wave velocity changes from 0 down to 10 m. During melting periods, both a sudden velocity decrease and a decorrelation of the seismic responses were observed. These effects can probably be explained by the increased water content of the active layer. In the second part of our study, we focused on detecting microseismic signals generated in and around the rock glacier. This seismic activity (microquakes and rockfalls) also exhibits seasonal variations, with a maximum in spring and summer, which correlates principally with an exacerbated post-winter erosional phase of the front and a faster rock glacier displacement rate. In addition, we observed short bursts of microseismicity, both during snowfall and during rapid melting periods, probably due to pore pressure increase. Article in Journal/Newspaper permafrost Oxford University Press Geophysical Journal International 221 3 1719 1735 |
institution |
Open Polar |
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Oxford University Press |
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croxfordunivpr |
language |
English |
description |
SUMMARY A network of seismometers has been installed on the Gugla rock glacier since October 2015 to estimate seismic velocity changes and detect microseismicity. These two processes are related to mechanical and structural variations occurring within the rock glacier. Seismic monitoring thus allows a better understanding of the dynamics of rock glaciers throughout the year. We observed seasonal variations in seismic wave velocity and microseismic activity over the 3 yr of the study. In the first part of our analysis, we used ambient noise correlations to compute daily changes of surface wave velocity. In winter, seismic wave velocities were higher, probably due to refreezing of the permafrost active layer and cooling of the uppermost permafrost layers, leading to increased overall rigidity of the medium. This assumption was verified using a seismic model of wave propagation that estimates the depth of P- and S-wave velocity changes from 0 down to 10 m. During melting periods, both a sudden velocity decrease and a decorrelation of the seismic responses were observed. These effects can probably be explained by the increased water content of the active layer. In the second part of our study, we focused on detecting microseismic signals generated in and around the rock glacier. This seismic activity (microquakes and rockfalls) also exhibits seasonal variations, with a maximum in spring and summer, which correlates principally with an exacerbated post-winter erosional phase of the front and a faster rock glacier displacement rate. In addition, we observed short bursts of microseismicity, both during snowfall and during rapid melting periods, probably due to pore pressure increase. |
author2 |
Labex UGA INSU,CNRS ANR |
format |
Article in Journal/Newspaper |
author |
Guillemot, Antoine Helmstetter, Agnès Larose, Éric Baillet, Laurent Garambois, Stéphane Mayoraz, Raphaël Delaloye, Reynald |
spellingShingle |
Guillemot, Antoine Helmstetter, Agnès Larose, Éric Baillet, Laurent Garambois, Stéphane Mayoraz, Raphaël Delaloye, Reynald Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling |
author_facet |
Guillemot, Antoine Helmstetter, Agnès Larose, Éric Baillet, Laurent Garambois, Stéphane Mayoraz, Raphaël Delaloye, Reynald |
author_sort |
Guillemot, Antoine |
title |
Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling |
title_short |
Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling |
title_full |
Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling |
title_fullStr |
Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling |
title_full_unstemmed |
Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling |
title_sort |
seismic monitoring in the gugla rock glacier (switzerland): ambient noise correlation, microseismicity and modelling |
publisher |
Oxford University Press (OUP) |
publishDate |
2020 |
url |
http://dx.doi.org/10.1093/gji/ggaa097 http://academic.oup.com/gji/advance-article-pdf/doi/10.1093/gji/ggaa097/32757348/ggaa097.pdf http://academic.oup.com/gji/article-pdf/221/3/1719/32960456/ggaa097.pdf |
genre |
permafrost |
genre_facet |
permafrost |
op_source |
Geophysical Journal International volume 221, issue 3, page 1719-1735 ISSN 0956-540X 1365-246X |
op_rights |
https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model |
op_doi |
https://doi.org/10.1093/gji/ggaa097 |
container_title |
Geophysical Journal International |
container_volume |
221 |
container_issue |
3 |
container_start_page |
1719 |
op_container_end_page |
1735 |
_version_ |
1810471467245109248 |