地球内核边界区域精细结构的地震学研究

项目名称： 地球内核边界区域精细结构的地震学研究

项目编号： No.40874020

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 王彦宾

作者单位： 北京大学

项目金额： 45万元

中文摘要： 地震学方法是研究地球内核边界（ICB）结构的重要手段。本项目收集新的内核边界反射震相资料，着重发展适于ICB区域精细结构模型高频地震波场模拟的并行数值方法，通过异常区域的内核边界反射震相的波形模拟，提供ICB区域精细结构的地震学证据。研究取得的主要成果包括：（1）成功地发展了基于交错网格伪谱法的内核边界反射震相数值模拟方法，利用该方法，详细探讨了地球内核边界区域精细结构异常（地形起伏、密度跃变、速度跃变、随机结构）所造成的PKiKP震相的差异。（2）基于交错网格伪谱法和高阶精度交错网格有限差分法，成功开发了区域三维模型地震波传播并行计算方法和程序，完成了程序的编写与调试、精度、效率检验以及应用实例计算。（3）基于反射率法和小生境遗传算法，成功发展了利用区域宽频带三分量地震波形资料反演地壳速度结构的方法，并应用于甘肃东南部地区，取得了较好结果。（4）开发了基于伪谱法模拟横向非均匀全地球模型中SH波传播的计算方法，以及基于交错网格伪谱法模拟全球地震波场时，如何避免模型中地球球心数学奇异性的坐标转换方法。（5）开展了全月球模型中月震波传播的数值计算，讨论了月震波的传播特征。

中文关键词： 内核边界; 精细结构; 地震波形反演; 并行计算; 交错网格

英文摘要： Seismological method plays very important roles in the study of structure at the inner core boundary (ICB) of the Earth. In this project, we try to collect new observation data of ICB reflections. We mainly focus on the development of parallel high-frequency seismic wavefield modeling method for regional models with fine heterogeneous structure at ICB region. Using waveform modeling, we try to provide seismological evidence for the fine heterogeneous structures at the ICB region.The major research results and progresses include: (1) Developed successfully a numerical scheme based on staggered grid pseudospectral method for ICB reflection modeling, and applied it to discuss the PKiKP waveform anomalies caused by heterogeneities at ICB such as topography, density, velocity and random velocity variation. (2) Developed successfully a parallel algorithm for 3D regional seismic wavefield modeling based on staggered grid pseudospectral and finite difference method. Verified the accuracy, validity and efficiency of the computer codes, and applied it to a realistic model. (3) Developed a waveform inversion method for regional crustal structure using 3 component broadband seismic data based on reflectivity method and niching genetic algorithm, and applied it to Southeastern Gansu and got interesting results. (4) Developed a scheme based on pseudospectral method for SH wavefield simulation in lateral heterogeneous whole earth model, and proposed a coordinate transformation method to solve the singularity problem at the center of the earth for staggered grid global wavefield modeling. (5) Applied global seismic wavefield simulation method to the whole Moon model, and discussed the characteristics of global seismic wave propagation from moonquake.

英文关键词： inner core boundary; fine structure; seismic waveform inversion; parallel computation; staggered grid