Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes
Rupture fronts can cause fault displacement, reaching speeds up to several ms(−1) within a few milliseconds, at any distance away from the earthquake nucleation area. In the case of silicate-bearing rocks the abrupt slip acceleration results in melting at asperity contacts causing a large reduction...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Nature Publishing Group
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639853/ https://www.ncbi.nlm.nih.gov/pubmed/26552964 http://dx.doi.org/10.1038/srep16112 |
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author | Spagnuolo, Elena Plümper, Oliver Violay, Marie Cavallo, Andrea Di Toro, Giulio |
author_facet | Spagnuolo, Elena Plümper, Oliver Violay, Marie Cavallo, Andrea Di Toro, Giulio |
author_sort | Spagnuolo, Elena |
collection | PubMed |
description | Rupture fronts can cause fault displacement, reaching speeds up to several ms(−1) within a few milliseconds, at any distance away from the earthquake nucleation area. In the case of silicate-bearing rocks the abrupt slip acceleration results in melting at asperity contacts causing a large reduction in fault frictional strength (i.e., flash weakening). Flash weakening is also observed in experiments performed in carbonate-bearing rocks but evidence for melting is lacking. To unravel the micro-physical mechanisms associated with flash weakening in carbonates, experiments were conducted on pre-cut Carrara marble cylinders using a rotary shear apparatus at conditions relevant to earthquakes propagation. In the first 5 mm of slip the shear stress was reduced up to 30% and CO(2) was released. Focused ion beam, scanning and transmission electron microscopy investigations of the slipping zones reveal the presence of calcite nanograins and amorphous carbon. We interpret the CO(2) release, the formation of nanograins and amorphous carbon to be the result of a shock-like stress release associated with the migration of fast-moving dislocations. Amorphous carbon, given its low friction coefficient, is responsible for flash weakening and promotes the propagation of the seismic rupture in carbonate-bearing fault patches. |
format | Online Article Text |
id | pubmed-4639853 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Nature Publishing Group |
record_format | MEDLINE/PubMed |
spelling | pubmed-46398532015-11-16 Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes Spagnuolo, Elena Plümper, Oliver Violay, Marie Cavallo, Andrea Di Toro, Giulio Sci Rep Article Rupture fronts can cause fault displacement, reaching speeds up to several ms(−1) within a few milliseconds, at any distance away from the earthquake nucleation area. In the case of silicate-bearing rocks the abrupt slip acceleration results in melting at asperity contacts causing a large reduction in fault frictional strength (i.e., flash weakening). Flash weakening is also observed in experiments performed in carbonate-bearing rocks but evidence for melting is lacking. To unravel the micro-physical mechanisms associated with flash weakening in carbonates, experiments were conducted on pre-cut Carrara marble cylinders using a rotary shear apparatus at conditions relevant to earthquakes propagation. In the first 5 mm of slip the shear stress was reduced up to 30% and CO(2) was released. Focused ion beam, scanning and transmission electron microscopy investigations of the slipping zones reveal the presence of calcite nanograins and amorphous carbon. We interpret the CO(2) release, the formation of nanograins and amorphous carbon to be the result of a shock-like stress release associated with the migration of fast-moving dislocations. Amorphous carbon, given its low friction coefficient, is responsible for flash weakening and promotes the propagation of the seismic rupture in carbonate-bearing fault patches. Nature Publishing Group 2015-11-10 /pmc/articles/PMC4639853/ /pubmed/26552964 http://dx.doi.org/10.1038/srep16112 Text en Copyright © 2015, Macmillan Publishers Limited http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
spellingShingle | Article Spagnuolo, Elena Plümper, Oliver Violay, Marie Cavallo, Andrea Di Toro, Giulio Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes |
title | Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes |
title_full | Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes |
title_fullStr | Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes |
title_full_unstemmed | Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes |
title_short | Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes |
title_sort | fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639853/ https://www.ncbi.nlm.nih.gov/pubmed/26552964 http://dx.doi.org/10.1038/srep16112 |
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