上地壳二维 Pg 波成像方法及几个应用实例裴顺平

上地壳二维Pg波成像方法及几个应用实例裴顺平上地壳二维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(Bk/Ak) +90 (Pei et al., 2012, Tectonophysics)

Pn Tomography

(Pei et al., 2007, JGR)

Station Source Crust Upper mantle ML Amplitude Tomography (Pei et al., 2006, BSSA)

2D Pg Tomography (Pei and Chen, 2012, BSSA)

实例一：玉树地震 (Pei and Chen, 2012, BSSA)

Yong Zhang et al. Weimin Wang et al. Koketsu et al.

7157 Pg arrival times 1689 Earthquakes 11 Stations Depth： 8.6 2.1 km Epicenter Distance: 76  38 km

Resolution Test 15’ 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

Thank you for your attention!

上地壳二维 Pg 波成像方法 及几个应用实例 裴顺平