0568864 - GFÚ 2024 RIV US eng J - Journal Article
Šílený, Jan - Cesca, S. - Hofstetter, R.
Single-station estimates of the focal mechanism for weak earthquakes.
Seismological Research Letters. Roč. 94, 2A (2023), s. 944-960. ISSN 0895-0695. E-ISSN 1938-2057
Institutional support: RVO:67985530
Keywords : moment tensors * source parameters * inversion
OECD category: Volcanology
Impact factor: 2.6, year: 2023 ; AIS: 1.067, rok: 2023
Method of publishing: Limited access
Result website:
https://pubs.geoscienceworld.org/ssa/srl/article/94/2A/944/619557/Single-Station-Estimates-of-the-Focal-MechanismDOI: https://doi.org/10.1785/0220220096

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.
Permanent Link: https://hdl.handle.net/11104/0340127