Comparison of Natural Seismic Numerical Simulation and Practical Example
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摘要: 为了解决长时间正演模拟的不稳定性问题, 实现天然地震波场长时间数值模拟.在高阶有限差分数值模拟的基础上, 给出了多轴向完全匹配吸收边界(M-PML)二维划分方式, 讨论了M-PML吸收边界转换系数P的取值对其吸收能力与截断误差对数值模拟有效信号的影响.实现了二维弹性波高阶有限差分的长时间数值模拟.采用2013年12月16日湖北省巴东县地震及余震信息, 对该地震数据进行了数值模拟, 并与武汉、秭归两台站数据进行了分析和讨论, 验证该正演模拟方法的正确性和有效性.为天然地震波场传播规律、成像和震相识别及震源定位等研究提供了基础.
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关键词:
- 多轴向完全匹配吸收边界 /
- 高阶交错网格有限差分 /
- 地震台站 /
- 天然地震
Abstract: In order to resolve the long-time forward modeling instability and realize the long-time numerical simulation of natural seismic wave field, based on staggered-grid high-order difference method, the 2-D model partitioning way of M-PML is provided, the value of the M-PML absorbing boundary conversion coefficient P and its influence on the absorption capacity and the influence on effective signal made by truncation error are discussed, the 2D elastic wave long time numerical simulation using higher-order finite difference is realized. In addition, combining the data of the 5.5 magnitude earthquake which occurred in Hubei Badong on December 16, 2013 and its aftershock recorded by Wuhan and Zigui Seismograph Stations, the practical significance of the forward modeling method is verified. The results can provide a basis for the research of the propagation law, imaging, phase identification and hypocentral location of natural seismic wave field. -
图 4 2层水平介质PML/M-PML吸收边界数值模拟
A图PML吸收边界方法:(A1)至(A3)分别是t=3.0 s、6.0 s、350 s时刻Vx快照,(A4)和(A5)分别为0至80 s、270 s至350 s时间Vx剖面记录;B图M-PML吸收边界方法:(B1)至(B3)分别是t=3.0 s、6.0 s、350 s时刻Vx快照,(B4)和(B5)分别为0至80 s、270 s至350 s时间Vx剖面记录
Fig. 4. Map of two layer horizontal medium numerical simulation with PML/M-PML absorbing boundary
表 1 交错网格一阶导数的偶数阶精度有限差分系数
Table 1. The even order accuracy finite difference coefficient table of first derivative staggered grid
精度(阶数) C1 C2 C3 C4 截断误差系数 2 1.0000000E+00 4.1666667E-02 4 1.1250000E+00 -4.1666667E-02 -4.6875000E-03 6 1.1718750E+00 -6.5104167E-02 4.6875000E-03 6.9754464E-04 8 1.1962891E+00 -7.9752604E-02 9.5703125E-03 -6.9754464E-04 -1.1867947E-04 ⋮ ⋮ ⋮ ⋮ ⋮ ⋮ ∞ 1.2732395E+00 -1.4147106E-01 5.0929581E-02 -2.5984480E-02 0 表 2 模型参数
Table 2. Model parameters
模型大小(km) ΔX=ΔZ(m) Bx=Bz(网格点) ΔT(s) F(Hz) Vp(m/s) Vs(m/s) ρ(g/cm3) 40×40 200 100 0.01 1 5 040 2 990 2.56 表 3 模型参数
Table 3. Model parameters
模型大小(km) ΔX=ΔZ(m) Bx=Bz(网格点) ΔT(s) F(Hz) H1(km) 40×30 200 100 0.01 1 15 Vp1(m/s) Vs1(m/s) ρ1(g/cm3) Vp2(m/s) Vs2(m/s) ρ2(g/cm3) 5 040 2 990 2.5 5 400 3 000 2.56 表 4 模型参数
Table 4. Model parameters
模型大小(km) ΔX=ΔZ(m) Bx=Bz(网格点) ΔT(s) F(Hz) Vp(m/s) Vs(m/s) ρ(g/cm3) 300×300 1.0 100 0.000 1 35 1 000 550 2.0 表 5 模型参数
Table 5. Model parameters
层号 Vp(m/s) Vs(m/s) ρ(g/cm3) H(m) ΔX=ΔZ(m) Bx=Bz(网格点) 1 2 200 1 000 2.0 800 50 50 2 2 900 1 500 2.3 1 500 50 50 3 3 900 2 000 2.9 2 700 50 50 表 6 震源参数
Table 6. Source parameters
震源 水平坐标(m) 深度坐标(m) 激发时间(s) 1 2 500 0 0 2 3 000 1 000 10 3 500 0 20 4 3 500 1 000 20 5 3 000 1 000 600 6 3 500 0 1 000 7 2 000 0 1 400 8 2 500 0 17 990 表 7 巴东地震信息
Table 7. Badong earthquake information
地震编号 发震时间(年-月-日T时∶分∶秒) 纬经度 深度(km) 震级(M) 主震 2013-12-16 T 13∶04∶52 31.1°N,110.5°E 10 5.5 余震1 2013-12-16 T 13∶14∶06 31.1°N,110.4°E 8 3.0 余震2 2013-12-16 T 13∶29∶15 31.1°N,110.3°E 6 2.3 余震3 2013-12-16 T 13∶30∶55 31.1°N,110.4°E 8 2.0 余震4 2013-12-16 T 14∶36∶24 31.1°N,110.4°E 5 2.4 余震5 2013-12-16 T 16∶16∶59 31.1°N,110.4°E 7 2.9 余震6 2013-12-16 T 19∶18∶33 31.1°N,110.4°E 6 2.1 余震7 2013-12-16 T 20∶33∶48 31.1°N,110.4°E 8 2.0 余震8 2013-12-16 T 21∶41∶06 31.1°N,110.4°E 6 2.1 余震9 2013-12-16 T 21∶46∶24 31.2°N,111.4°E 5 2.0 余震10 2013-12-16 T 22∶42∶08 31.0°N,110.3°E 6 2.1 表 8 地层信息
Table 8. Stratigraphic information
深度(km) Vp(m/s) Vs(m/s) 0.0~4.0 5 040 2 990 4.0~6.0 5 400 3 000 6.0~10.0 5 760 3 320 10.0~16.0 5 880 3 350 16.0~20.0 6 160 3 510 20.0~25.0 6 540 3 700 25.0~35.0 6 830 3 900 35.0~50.0 7 470 4 270 50.0~80.0 8 100 4 600 80.0以下 7 600 4 300 -
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