首页|Source process of the September 21, 2020 M-w 5.6 Bystraya earthquake at the South-Eastern segment of the Main Sayan fault (Eastern Siberia, Russia)

Source process of the September 21, 2020 M-w 5.6 Bystraya earthquake at the South-Eastern segment of the Main Sayan fault (Eastern Siberia, Russia)

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  • NSTL
  • Elsevier
We study the M-w 5.6 Bystraya earthquake, occurred on September 21, 2020 at the SW flank of the Baikal rift zone in the area, in which only few small seismic events have been detected during the whole period of instrumental observations. Source parameters of the mainshock and its largest aftershock (M-w 4.7) are inverted from intermediate-period surface wave amplitude spectra. Hypocentral depths and seismic moment tensors in a double-couple approximation are calculated for both earthquakes, while integral source characteristics, describing its spatio-temporal development, are estimated only for the mainshock. For the Bystraya earthquake, directivity effects (rupture direction and velocity) are also modelled. The obtained results show that the study seismic event can be associated with activation of the SE segment of the Main Sayan fault. The faults of the mainshock and its largest aftershock are formed under the influence of the NW-SE extension and NE-SW compression. The predominance of left-lateral strike-slip motions agrees well with previous studies at the SW flank of the Baikal rift zone. A small thrust-fault component could reflect the inversion uplift of some blocks of the Bystraya basin bottom as well as the Bystrinskaya Sopka massif. The dipping of the earthquake fault plane could indicate flattening of the considered fault segment at some depth or the existence of differently oriented structural discontinuities inside the fault zone of a finite width. The long rupture of the Bystraya earthquake could be connected with its almost pure strike-slip focal mechanism and orientation of the rupture plane approximately along the Main Sayan fault strike.

EarthquakeSeismic moment tensorSource parametersSurface wavesSW flank of the Baikal rift zoneMain Sayan faultBAIKAL RIFT-ZONESOURCE PARAMETERSUPPER-MANTLEEARTHS CRUSTGLUT MOMENTSTUNKA RIFTRUPTURE PROCESSSEISMIC SOURCESGLOBAL CATALOGDEEP-STRUCTURE

Gileva, Nadezhda A.、Filippova, Alena, I、Bukchin, Boris G.、Fomochkina, Anastasiya S.、Melnikova, Valentina, I、Radziminovich, Yan B.

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RAS

Inst Earths Crust SB RAS

2022

10.1016/j.tecto.2021.229162

Tectonophysics

Tectonophysics

EISCI
ISSN：0040-1951
年,卷(期)：2022.822
  • 10
  • 108