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Tectonic stress changes related to plate spreading prior to the 2021 Fagradalsfjall eruption in SW Iceland
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SYSNO ASEP 0570375 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Tectonic stress changes related to plate spreading prior to the 2021 Fagradalsfjall eruption in SW Iceland Author(s) Hrubcová, Pavla (GFU-E) ORCID, RID
Vavryčuk, Václav (GFU-E) ORCID, RIDArticle number 229761 Source Title Tectonophysics. - : Elsevier - ISSN 0040-1951
Roč. 851, March (2023)Number of pages 12 s. Publication form Print - P Language eng - English Country NL - Netherlands Keywords focal mechanisms ; seismic moment tensors ; tectonic stress ; Fagradalsfjall eruption ; Reykjanes Peninsula Subject RIV DC - Siesmology, Volcanology, Earth Structure OECD category Volcanology R&D Projects GA22-10747S GA ČR - Czech Science Foundation (CSF) TO01000198 GA TA ČR - Technology Agency of the Czech Republic (TA ČR) Method of publishing Open access Institutional support GFU-E - RVO:67985530 UT WOS 000949803200001 EID SCOPUS 85149177988 DOI 10.1016/j.tecto.2023.229761 Annotation The Reykjanes Peninsula in SW Iceland is a part of the Mid-Atlantic plate boundary. It forms its transtensional segment with several volcanic and faulting systems. We focus on the 2017 seismicity that occurred in the central part of Reykjanes at the place of the Fagradalsfjall volcano prior to its eruption on March 19, 2021. We invert well-determined focal mechanisms of the 2017 seismicity and provide mapping of tectonic stress in space and time. Our results disclose heterogeneous stress field manifested by mix of shear, tensile and compressive frac-turing. The prominent stress direction was in the azimuth of 120 degrees +/- 8 degrees, which represents the overall extension related to rifting in the Reykjanes Peninsula. The activity initiated on the transform fault segment with pre-dominantly shear strike-slip events. The non-shear fractures occurred later being associated with normal dip-slips and corresponding to the opening of volcanic fissures trending in the azimuth of 30-35 degrees, perpendicular to the extension. The dip-slips were mainly located above an aseismic dike detected in the centre of the 2017 swarm. This dike represents a zone of crustal weakening during a preparatory phase of the future 2021 Fagradalsfjall volcanic eruption located at the same place. Moreover, we detected local variation of stress when the stress axes abruptly interchanged their directions in the individual stress domains. These stress changes are interpreted in a consequence of plate spreading and upcoming fluid flow during a preparatory phase of a rifting episode. Workplace Geophysical Institute Contact Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Year of Publishing 2024 Electronic address https://www.sciencedirect.com/science/article/pii/S0040195123000598
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