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Single-station estimates of the focal mechanism for weak earthquakes
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SYSNO ASEP 0568864 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Single-station estimates of the focal mechanism for weak earthquakes Author(s) Šílený, Jan (GFU-E) ORCID, RID
Cesca, S. (DE)
Hofstetter, R. (IL)Source Title Seismological Research Letters. - : Seismological Society of America - ISSN 0895-0695
Roč. 94, 2A (2023), s. 944-960Number of pages 17 s. Publication form Print - P Language eng - English Country US - United States Keywords moment tensors ; source parameters ; inversion Subject RIV DC - Siesmology, Volcanology, Earth Structure OECD category Volcanology Method of publishing Limited access Institutional support GFU-E - RVO:67985530 UT WOS 000944198000005 EID SCOPUS 85151039800 DOI https://doi.org/10.1785/0220220096 Annotation The focal mechanism is a parameter of an earthquake that typically demands observa-tions surrounding the focus. If such observations are not available, only limited infor-mation can be retrieved regarding the process of rupturing (e.g., geometry, and the orientation of the fault plane and slip), not its shear versus non-shear nature. In extreme cases of monitoring that incorporate a single station, a mechanism can only be esti-mated if data from additional seismic phases are available. However, such is not the case for weak seismic events, in which a station often only records direct P and S waves. Under such conditions, information is severely limited, and standard synthetics-to-data-matching does not allow even the simplest and most constrained seismological source model, namely a double-couple focal mechanism, to be determined. During data review, we detected an internal ambiguity for solutions of the inverse task using sin-gle-station geometry. Nevertheless, we found that at least some important features of a focal mechanism may be retrieved. Such scenarios occur for particular configurations of focal mechanism orientation and source-station direction, as follows: (1) If a station lies in a direction within the quadrant of compressions, the Taxis can be retrieved with reasonable error. However, the P axis remains ambiguous. (2) Conversely, if a station lies in a direction within the quadrant of dilatations, reasonable resolution of the P axis is possible, while the T axis remains ambiguous. (3) If the data are noisy, apart from extreme cases of contamination, the possibility of estimating the direction of the T/P axis remains intact. The closer source-station direction is to the center of the quadrant of compressions or dilatations, the better the resolution of the T/P axis. Our method was applied to selected weak earthquakes recorded by the three-component borehole seis-mic station MDBI, located near the Dead Sea in Israel. Workplace Geophysical Institute Contact Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Year of Publishing 2024 Electronic address https://pubs.geoscienceworld.org/ssa/srl/article/94/2A/944/619557/Single-Station-Estimates-of-the-Focal-Mechanism
Number of the records: 1