利用GPS位移反演日本M_w9.0仙台地震及M_w7.9强余震静态位错模型
摘要
基于GPS观测的Mw9.0日本仙台地震同震形变及震后8h的地表形变,考虑分层介质模型的影响,反演了主震及震后8h的断层的位错分布.结果显示,主震位错对应的矩震级为Mw8.98,最大同震位错量可达23.3m,在震中区显示出纯逆冲特性,震中两侧断层错动显示出一定的走滑分量.另外,约90%的地震能量发生在40km深度以上.而由震后8h的地表形变反演的结果显示,这一期间释放能量约相当于一个Mw8.13的地震,位错主要分布在主震破裂的西南区域,最大位错量约1.5m,破裂峰值区与Mw7.9强余震有明显的对应关系,暗示震后8h的断层错动主要是由Mw7.9强余震引起的.另外,主震破裂的深部延伸面在震后0.2～0.4m的滑动可能主要是无震余滑.
引文
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2Hashimoto C,Noda A,Sagiya T,et al.Interplate seismogenic zones along the Kuril-Japan trench inferred from GPS data inversion.Nat Geosci,2009,2:141-144
3Shen Z K,Sun J B,Zhang P Z,et al.Slip maxima at fault junctions and rupturing of barriers during the2008Wenchuan earthquake.Nat Geosci,2009,2:718-724
4Wang L,Wang R,Roth F,et al.Afterslip and viscoelastic relaxation following the1999M7.4ímit earthquake,from GPS measurements.Geophys J Int,2009,178:1220-1237
5Huang Z,Zhao D,Wang L.Seismic heterogeneity and anisotropy of the honshu arc from the japan trench to the japan sea.Geophys J Int,2011,184:1428-1444
6Miura S,Takahashi N,Nakanishi A,et al.Structural characteristics off Miyagi forearc region,the Japan Trench seismogenic zone,de-duced from a wide-angle and refraction study.Tectonophysics,2005,407:165-188
7Mooney W D,Laske G,Masters T G.CRUST5.1:A global crustal model at5°×5°.J Geophys Res,1998,103:727-747
8Diao F Q,Xiong X,Wang R.Mechanism of transient post-seismic deformation following the2001Mw7.8Kunlun(China)earthquake.Pure Appl Geophys,2010,168:767-779
9Wang R,Lorenzo-Martín F,Roth F.PSGRN/PSCMP-A new code for calculating co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory.Comput Geosci,2006,32:527-541
10Bakun W H,King G C P,Cockerham R S.Seismic slip,aseisimic slip,and the mechanics of repeating earthquakes on the Calaveras Fault,California,in Earthquake Source Mechanics.In:Das S,Boatright J,Scholz C H,eds,Geophys Monogr Ser,vol37.Washington D C:AGU,1986.195-207
11Mendoza C,Hartzell S H.Aftershock patterns and main shock faulting.Bull Seism Soc Am,1988,78:1438-1449
12Wessel P,Smith W H F.Free software helps map and display data.Eos Trans Am Geoph,1991,72:445-446
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