上地壳二维 pg 波成像方法 及几个应用实例 裴顺平
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上地壳二维 Pg 波成像方法 及几个应用实例 裴顺平. 中国科学院青藏高原研究所 2012-11-08, 中科大. 3D Tomography. Moho. ( 张国民等, 2002). 2D Pg Tomography. (Pei and Chen, 2012, BSSA). Anisotropy. 波速各向异性的大小为 波速最快方向方位角为 1/2arctan( B k / A k ) +90. (Pei et al., 2012, Tectonophysics). Pn Tomography. (Pei et al., 2007, JGR). - PowerPoint PPT PresentationTRANSCRIPT
上地壳二维 Pg波成像方法及几个应用实例
裴顺平
中国科学院青藏高原研究所
2012-11-08, 中科大
Moho
3D Tomography
(张国民等, 2002)
2D Pg Tomography
2 2( ) / /obs sta evtt h v v t t
ij i j ijk kk
t a b d s
obs sta evtt t t t 2 2 /t h v
(Pei and Chen, 2012, BSSA)
Anisotropy
ij i j ijk kk
t a b d s ( cos 2 sin 2 )ij i j ijk k k k
k
t a b d s A B
波速各向异性的大小为
波速最快方向方位角为 1/2arctan(Bk/Ak) +90
2/122 )( kk BA
(Pei et al., 2012, Tectonophysics)
ij i j ijk kk
t a b d s Ax b
Earthquake
Station
M oho kijkjiij Sdbat
2sin2cos kkkk BAsS
Pn Tomography
(Pei et al., 2007, JGR)
ML Amplitude Tomography
Source
Station
Crust
Upper mantle
( ) ( ) ( ) ( ) ( ) ( , )ij j i i ij ijA f O f I f S f G R B f R1
0ln ( ) ln ( )ij ij ij i jY A f G R a b Q cR
(Pei et al., 2006, BSSA)
2D Pg Tomography
2 2( ) / /obs sta evtt h v v t t
ij i j ijk kk
t a b d s
obs sta evtt t t t 2 2 /t h v
(Pei and Chen, 2012, BSSA)
实例一:玉树地震
(Pei and Chen, 2012, BSSA)
Weimin Wang et al.
Yong Zhang et al.
Koketsu et al.
7157 Pg arrival times1689 Earthquakes 11 Stations
Depth :8.6 2.1 km
Epicenter Distance:76 38 km
0.046.02
t
Resolution Test15’ 15’
Table 1. Average velocity in the three sub-regions
Sub-region Number of ray paths Average velocity (km/s) Tomographic velocity A 672 6.45 Fast anomaly B 363 5.82 Slow anomaly
C 163 5.83 Slow anomaly
稳定性测试
• Origin time 0.2s errors
• Source depth 10km
• Both
Why Anisotropy
• Anisotropy ?• Crack direction
• Crack density
(Pei et al., 2012, Tectonophysics)
120
(Pei et al., 2012, Tectonophysics)
Without Anisotropy With Anisotropy
( Yao et al , 2010)
Summary
• Simple 2D tomography method
• Seismic velocity structure controls the origination (stress accumulation) and rupture propagation and distribution of aftershocks as well
• Pg anisotropy implies direction and density of micro-crack
总结
• Pg 二维成像方法简单有效• 高分辨率成像能够提供新的结
构信息(裂隙,介质变化)• 浅层精细结构能够提供地质可
比性