CAP M S Wallace. Vol. 27 No. 2 Jun EARTHQUAKE RESEARCH IN CHINA M S 4. 8 CAP. 3km - - P315

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1 ~ EARTHQUAKE RESEARCH IN CHINA Vol. 27 No. 2 Jun CAP ~ 214 CAP CAP M S 4. 8 M W = 4. 1 I II km - - M S 4. 8 CAP P315 A km M S ~ M S M S CAP M S Helmberger 1980 P P&Pn1 Wallace dequanh@ mail. ustc. edu. cn

2 Dreger et al 1993 Walter 1993 Ritsema et al 1995 Ichinose et al Moho Chandan et al 2006 Doser et al 1988 Dreger et al Pasyanos et al 1996 Thio et al 1995 Du et al 2003 Zhao 1994 Pnl Snl Zhu 1996 CAP Zheng et al Zhao 1994 u t S t S j t = M 0Σ 3 i = 1 A ij - θ δ λ G ij h Δ t j = G ij A ij M 0 φ Δ h θ λ u t = s t u t s t - F-K Zhu et al 2002 Zhao 1994 CAP P Pnl Sur 3 5 Pnl e = u t - s t 4 e = u t - s t u t s t

3 2 CAP km CAP F-K Zhu et al 2002 M S CAP

4 F-K % 15 v S v p 1 /3 80% 24 53% 60% 33 km km /s km /s g/cm -3 Q P Q S % CAP M W CAP km P ~ 0. 2Hz ~ 0. 1Hz

5 2 CAP km M S km 3 3 CAP M L > 4. 0 CAP M S FOCMEC km 9km 9km 3km 3km M S km - 50km M S M S NEE SE NE 130km 2010 CAP -

6 km - NNE NNE 16 NNE M S ~ 6 NNE M S ~ M W ~ ~ ~ M S 5. 7 M S ~ ~ P ~ ~ ~ ~ CAP 1 25 ~ CAP ~ 84 Du W X Kim W Y Sykes L R 2003 Earthquake source parameters and state of stress for the northeastern united states and southeastern Canada from analysis of regional seismograms. Bul1 Seism Soc Am ~ l648. Doser D I 1988 Ource parameters of earthquakes in the Nevada seismic zone 1915 ~ 1943 J Geophys Res 93 B l ~ Dreger D S Helmberger D V 1990 Broadband modeling of local earthquakes Bul1 Seis Soc Am ~ Dreger D S Tkalcic H Johnston M 2000 Dilational processes accompanying earthquakes in the Long Valley Caldera Scienc 288 l22 ~ 125. Dreger D S Helmherger D V 1993 Determination of source network data J Geophys Res ~ parameters at regional distances with three-component sparse

7 2 CAP Helmberger D V Engen G R 1980 Modeling the long-period body waves from shallow earthquakes at regional ranges Bul1 Seism Soc Am ~ Ichinose G A Smith K D Anderson J G 1997 Source parameters of the 15 November Border Town Nevada earthquake sequence Bul1 Seism Soc Am ~ 667. Ichinose G A Smith K D Anderson J G 1998 Moment tensor inversion of the 1994 to 1996 Double Spring Flat Nevada earthquake sequence and implications for local tectonics models Bul1 Seism Soc Am ~ Ichinose G A Smith K D Anderson J G 1999 Seismic analysis of the 7 January 1998 chemical plant explosion at Kean Canyon Nevada Bul1 Seism Soc Am ~ 945. Pasyanos M E Dreger D S Romanowicz B 1996 Toward realtime estim ation of regional moment tensors Bul1 Seism Soc Am ~ Ritsema J Lay T l995 Long period regional wave moment tensor inversion for earthquakes in the western United States J Geophys Res ~ Saikia C K 2006 Modeling of the 21 May 1997 Jabalpur earthquake in central India source parameters and regional path calibration. Bul1 Seism Sac Am ~ Thio H K Kanamori H 1995 Moment-tensor inversion for local earthquakes using surface waves recorded at TERRAscope Bul1 Seism Soc Am ~ Wallace T C 1981 A technique for the inversion of regional data in source parameter studies J Geophys Res ~ Wallace T C Helmberger D V 1982 Determining source parameters of moderate-size earthquakes from regional waveforms Phys Earth Planet Interiors ~ 196 Walter W R 1993 Source parameters of the June Little Skull Mountain earthquake from complete regional waveform sat a single station Geophys Res Lett ~ 406. Zhao L S Helmberger D V 1994 Source estimation from broadband regional seismograms Bull Seis Soc Amer ~ 104. Zheng Y Ma H S Lv J et al 2009 Source mechanism of strong aftershocks M S 5. 6 of the 2008 /05 /12 Wenchuan earthquake and the implication for seismotectonics Science in China Series D Earth Sciences ~ 753. Zheng Y Ni S D Xie Z J et al 2010 Strong aftershocks in the northern segment of the Wenchuan earthquake rupture zone and their seismotectonic implications Earth Planets Space ~ 886. Zhu L P Helmberger D V 1996 Advancement in source estimation techniques using broadband regional seismograms Bull Seis Soc Amer ~ Zhu L P Rivera L A 2002 A note on the dynamic and static displacements from a point source in multilayered media Geophys J Int ~ 627.

8 Source mechanism of the 2011 M S 4. 8 Anqing earthquake determined from CAP method Hong Dequan 1 2 Wang Xingzhou 1 2 Han Libo 3 Qi Hao 1 Zhang Bing 1 1 Earthquake Administration of Anhui Province Hefei China 2 National Geophysical Observatory at Mengcheng Hefei China 3 Institute of Geophyiscs China Earthquake Administration Bejing China Abstract In this article we have inverted local broadband waveform data to determine the foca1 mechanism of 2011 Anqing M S 4. 8 earthquake. Our result shows that the best double couple solution of the M S 4. 8 event is and 120 for strike dip and rake angles respectively. The other nodal plane is the estimated focal depth is about 3km. The both strikes of the two nodal plane are significantly different with the strike of the Susong-Zongyang fault which has a low level of seismic activity since Late Quaternary. This implies that this earthquake may not occur on the Susong-Zongyang fault and we infer that a buried fault with strike of NNE may be the seismogenic structure of this event. Key words Anqing earthquake Cut and paste method Source mechanism