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二維非均質構造 折射射線成像

二維非均質構造 折射射線成像. 1. 正演 : 理論 , 程式 , 應用 2. 反演 : 理論 , 程式 , 應用. 戴富隆. date:10/28~12/30. 12/22~12/31. 中大陳浩維老師 提供正演射線追蹤 程式. NG. 熟悉均質及非均質 射線追蹤理論. 評估自行寫 正演程式. Seismic Ray Theory, V. Cerveny. Cambridge University Press 2001. OK. 以 平滑斜面斷層模型 進行正演程式運作 , 得到 走時曲線. 1/1 ~2/25.

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二維非均質構造 折射射線成像

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  1. 二維非均質構造折射射線成像 1. 正演 : 理論 , 程式 , 應用 2. 反演 : 理論 , 程式 , 應用 戴富隆

  2. date:10/28~12/30 12/22~12/31 中大陳浩維老師 提供正演射線追蹤 程式 NG 熟悉均質及非均質 射線追蹤理論 評估自行寫 正演程式 Seismic Ray Theory, V. Cerveny.Cambridge University Press 2001 OK 以平滑斜面斷層模型 進行正演程式運作, 得到走時曲線 1/1 ~2/25 1.Three-dimension geometrical ray theory and modelling of transmitted seismic energy of data from the Nevada Test Site How-Wei Chen , Geophysical Journal International 1998 2. Massive Parallel Computing of Shortest Raypath and Traveltime in 2-D and 3-D Models, How-Wei Chen ,TAO 1996

  3. 2/25~3/30 非均質可逆射線成像公式推導 並撰寫反演程式 NG Stability Analysis of Velocity Imaging of 2-D Multi-Layered Structures Through Inverse Reflected Rays Tan K. Wang SEG 2004 Prestack Inverse-Ray Imaging of A 2D Homogeneous Layer: A Tutorial Study Tan K. Wang TAO 2002 反演所得速度模型 進行誤差分析 4/1~4/14 OK 4/14~4/30 研究工作 階段總檢討

  4. 非均質構造折射射線 S R 彎曲的射線 射線追蹤法: 震源與測站間射線。 (可分震源出射法(shooting method)與二點射線追蹤法(two-point ray-tracing))。

  5. Ray tracing in a cell model S R Each cell indicates the velocity in km/s

  6. 非均質構造折射射線追蹤理論 • Reference: Seismic Ray Theory, Chap 3 • V. Cerveny , Cambridge University Press 2001 • Eikonal equation • Eikonal equationof high-frequency P and S wave propagating in smoothly inhomogeneous isotropic media • (T :travel time, p : slowness vector) • (∇T )2 =1/V 2 • In Cartesian coordinates, it reads: • pi pi = 1/V 2(xi) (xi: coordinate ,x or y or z) • p= ∇T =1/V êp direction of ray tracing

  7. Eikonal equation in 2D model (∇T )2 = (∇T ) ·(∇T ) = (∂T/∂x êi + ∂T/∂z êk) · (∂T/∂x êi + ∂T/∂z êk) = (∂T/∂x)2 + (∂T/∂z)2 = px2 + pz2 (p= ∇T ,px= p cos ,pz= p sin) x  z ∇T

  8. 2. The ray tracing system from Hamiltonian dxi /du = (pkpk)n/2-1pi dT /du = (pkpk)n/2=V-n dpi /du = (1/n) ∂V-n/∂xi u: displacement vector along the trajectory

  9. 1. n=0 , dT /du = 1,parameter u along the ray is directly equal to travel time T dxi /du = V2 pi dpi /du = - ∂ln(V)/∂xi 2. n=1 , dT /du = 1/V , parameter u along the ray is arclength s dxi /du = V pi dpi /du = ∂(1/V)/∂xi

  10. 可逆反射射線速度成像 由snell’s law導出各邊界RV值 RV= Vk+1/Vk = sin k+1/sin k Rv=-1/sinL Rv=1/sinR 反射區1a Rv=-cosL/sinR Rv=cosR/sinR 反射區1b 反射區2 Reference: Stability Analysis of Velocity Imaging of 2-D Multi-Layered Structures Through Inverse Reflected Rays Tan K. Wang

  11. 研究區域: 台灣東部海域琉球隱沒帶之 南澳海盆 Taiwan 1995美國尤英號研究震測船在 台灣東部海域進行炸測 EW95-1(line1)、EW95-14 (line14)與EW95-16(line16) 是海底地震儀資料

  12. P-Wave Velocity and Interface Along EW9509-14

  13. 結論: • 選取海底地震儀折射到達時間， • 以非均質構造折射射線成像反演南澳海盆的沈積及地殼速度模型。

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