Changing friction at the base of an Alpine glacier

Abstract Repeating earthquakes are a global phenomenon of tectonic faults. Multiple ruptures on the same fault asperities lead to nearly identical waveforms characteristic for these seismic events. We identify their microseismic counterparts beneath an Alpine glacier, where basal sliding accounts fo...

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Autores principales:	Dominik Gräff, Fabian Walter
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/1e2750c155b047f3bb18a9ed288681ea
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id	oai:doaj.org-article:1e2750c155b047f3bb18a9ed288681ea
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spelling	oai:doaj.org-article:1e2750c155b047f3bb18a9ed288681ea2021-12-02T14:49:11ZChanging friction at the base of an Alpine glacier10.1038/s41598-021-90176-92045-2322https://doaj.org/article/1e2750c155b047f3bb18a9ed288681ea2021-05-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-90176-9https://doaj.org/toc/2045-2322Abstract Repeating earthquakes are a global phenomenon of tectonic faults. Multiple ruptures on the same fault asperities lead to nearly identical waveforms characteristic for these seismic events. We identify their microseismic counterparts beneath an Alpine glacier, where basal sliding accounts for a significant amount of ice flow. In contrast to tectonic faults, Alpine glacier beds are subject to large variations in sliding velocity and effective normal stresses. This leads to inter- and sub-seasonal variations in released seismic moment from stick–slip asperities, which we explain with the rate-and-state friction formalism. During summer, numerically modelled effective normal stresses at asperities are three times higher than in winter, which increases the local shear resistance by the same factor. Stronger summer asperities therefore tend to form in bed regions well connected to the efficient subglacial drainage system. Moreover, asperities organise themselves into a state of subcriticality, transferring stresses between each other. We argue that this seismic stick–slip behavior has potentially far-reaching consequences for glacier sliding and in particular for catastrophic failure of unstable ice masses.Dominik GräffFabian WalterNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-10 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Dominik Gräff Fabian Walter Changing friction at the base of an Alpine glacier
description	Abstract Repeating earthquakes are a global phenomenon of tectonic faults. Multiple ruptures on the same fault asperities lead to nearly identical waveforms characteristic for these seismic events. We identify their microseismic counterparts beneath an Alpine glacier, where basal sliding accounts for a significant amount of ice flow. In contrast to tectonic faults, Alpine glacier beds are subject to large variations in sliding velocity and effective normal stresses. This leads to inter- and sub-seasonal variations in released seismic moment from stick–slip asperities, which we explain with the rate-and-state friction formalism. During summer, numerically modelled effective normal stresses at asperities are three times higher than in winter, which increases the local shear resistance by the same factor. Stronger summer asperities therefore tend to form in bed regions well connected to the efficient subglacial drainage system. Moreover, asperities organise themselves into a state of subcriticality, transferring stresses between each other. We argue that this seismic stick–slip behavior has potentially far-reaching consequences for glacier sliding and in particular for catastrophic failure of unstable ice masses.
format	article
author	Dominik Gräff Fabian Walter
author_facet	Dominik Gräff Fabian Walter
author_sort	Dominik Gräff
title	Changing friction at the base of an Alpine glacier
title_short	Changing friction at the base of an Alpine glacier
title_full	Changing friction at the base of an Alpine glacier
title_fullStr	Changing friction at the base of an Alpine glacier
title_full_unstemmed	Changing friction at the base of an Alpine glacier
title_sort	changing friction at the base of an alpine glacier
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/1e2750c155b047f3bb18a9ed288681ea
work_keys_str_mv	AT dominikgraff changingfrictionatthebaseofanalpineglacier AT fabianwalter changingfrictionatthebaseofanalpineglacier
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Changing friction at the base of an Alpine glacier

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