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Application of the shear-tensile source model to acoustic emissions in Westerly granite
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SYSNO ASEP 0531789 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Application of the shear-tensile source model to acoustic emissions in Westerly granite Author(s) Petružálek, Matěj (GLU-S) RID, SAI, ORCID
Jechumtálová, Zuzana (GFU-E) ORCID, RID
Šílený, Jan (GFU-E) ORCID, RID
Kolář, Petr (GFU-E) ORCID, RID
Svitek, Tomáš (GLU-S) SAI, RID
Lokajíček, Tomáš (GLU-S) RID, SAI, ORCID
Turková, I. (CZ)
Kotrlý, M. (CZ)
Onysko, R. (CZ)Article number 104246 Source Title International Journal of Rock Mechanics and Mining Sciences. - : Elsevier - ISSN 1365-1609
Roč. 128, April (2020)Number of pages 12 s. Publication form Print - P Language eng - English Country GB - United Kingdom Keywords fracturing ; acoustic emission ; source mechanism ; shear-tensile crack ; Westerly granite Subject RIV DC - Siesmology, Volcanology, Earth Structure OECD category Volcanology Subject RIV - cooperation Institute of Geology - Geology ; Mineralogy R&D Projects GA16-03950S GA ČR - Czech Science Foundation (CSF) GA18-08826S GA ČR - Czech Science Foundation (CSF) Method of publishing Limited access Institutional support GLU-S - RVO:67985831 ; GFU-E - RVO:67985530 UT WOS 000536484200008 EID SCOPUS 85079340829 DOI 10.1016/j.ijrmms.2020.104246 Annotation Traditionally in seismology and in acoustic emission (AE), full moment tensor (MT) is applied as a default model of the mechanism. We present an alternative - an application of shear tensile crack (STC) source model to AEs generated by uniaxial compression loading of Westerly granite. The advantages of STC over the conventional MT are as follows: (i) contrary to the MT, the STC is physical source since it describes straight and simple fracture modes anticipated inside a loaded sample, namely the shear-slip and both of opening and closing tensile cracks, and (ii) the STC is simpler because it is described by fewer parameters (five instead of six required for an unconstrained MT), an essential feature for stabilizing the inverse problem. Better suitability of STC over MT is demonstrated by three exemplary AEs (tensile, shear, and combined). The obtained results were confirmed using a statistical analysis of 1630 reliably determined source mechanisms. The STC, as compared to the MT, provides smaller confidence regions for orientation and even smaller regions for decomposition parameters. Thus, the STC solution appeared to be substantially more useful than the MT, namely for mechanisms with a high content of non-double-couple (non-DC) component, as it allowed better distinction between tensile and shear AEs. Grain scale cracks of tension and combined source type, localized within the middle-height circumferential portion of the specimen, dominated fracturing. Azimuthal distribution of fault planes was found to be approximately uniform for all three source types. The fault dip increased with increasing content of the non-DC component. The average values were 16 degrees, 21 degrees, and 26 degrees for the tensile, combined and shear source types, respectively. The specimen failed by flaking in areas of a high AE activity. AE locations and failure mechanisms indicate a perfect confinement end-boundary conditions between the tested specimen and the loading platens. Workplace Geophysical Institute Contact Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Year of Publishing 2021 Electronic address https://www.sciencedirect.com/science/article/pii/S1365160919310263
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