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[1]LI Yuli,LI Qilei.Preliminary Study of the Seismogenic Structure of the Biru,Tibet MS6.1 Earthquake[J].Journal of Seismological Research,2022,45(01):54-65.[doi:10.20015/j.cnki.ISSN1000-0666.2022.0007]

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Preliminary Study of the Seismogenic Structure of the Biru,Tibet M_S6.1 Earthquake

Journal of Seismological Research[ISSN 1000-0666/CN 53-1062/P] Volume: 45 Number of periods: 2022 01 Page number: 54-65 Column: Public date: 2022-01-20

Title:: Preliminary Study of the Seismogenic Structure of the Biru,Tibet M_S6.1 Earthquake

Author(s):: LI Yuli; LI Qilei; (Qinghai Earthquake Agency,Xining 810001,Qinghai,China)

Keywords:: the Biru M_S6.1 earthquake; the Double-difference reloction; focal mechanism; seismogenic structure

CLC:: P315.33

DOI:: 10.20015/j.cnki.ISSN1000-0666.2022.0007

Abstract:: The Double-difference location method is used to relocate the Biru,Tibet M_S6.1 earthquake sequence,and the optimized focal parameters of the mainshock and the distribution characteristics of the aftershocks are obtained; the epicenter of the mainshock is located at 31.924°N,92.824°E,and the focal depth is 12.8 km.The aftershocks are mainly distributed along the NE direction,with a length of 18 km or so.The depth profile in NE direction shows that there is an obvious seismic gap on the upper right part of the mainshock’s sourece,and the earthquakes outside the gap evenly distribute along the depth profile.This may be due to the obstacles in the seismic gap,which block the propagation of seismic ruptures in this direction.By using the CAP(Cut and Paste)waveform inversion method,the following parameters of the Biru eartqhuake are got:the depth of the optimal moment center of the main shock is 9.3 km.The moment magnitude M_W=5.98,and the focal mechanism solutions of the main shock—Nodal plane I has a strike of 347°,an inclination of 60°,a sliding angle of-135°.Nodal plane II has a strike of 230°,a dip of 52°,a sliding angle of-39°.P-axis has a strike of 203°,a dip of 52°.T-axis:strike=107°,inclination=5°.The difference between the focal depths obtained by the relocation method and the CAP waveform inversion method may reflect that the rupture of the mainshock starts in the deep and then develops to the shallow.The relocated aftershocks’ distribution,the focal mechanism solutions of mainshock,the historical earthquakes and geotectonic settings reveal that the normal,left-lateral,and strike-slip fault along the southern margin of the Anduo Basin may be the main seismogenic structure of the Biru M_S6.1 earthquake,and the seismogenic fault plane is nodal plane II.

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Last Update: 2022-01-20