High Resolution Imaging of Seismic Velocity Discontinuities

建议摘要EAR0106904(PH#45x)标题：地震速度不连续的高分辨率成像PI：Anne F.Sheehan，科罗拉多大学，Boulder地壳和地幔不连续的存在和深度分布的地震估计对于约束地球的成分、流变学和温度模型是重要的。该项目包括接收函数成像新方法的开发、测试和应用。发展了一种基尔霍夫式的偏移方法，它利用点散射方法处理非平面和横向不连续的界面。这种分析中的一个不确定性是三维不连续结构的偏向效应，它可能会错误地将特征投射到二维模型中。偏移反演将扩展到三维，并包括后向散射能量。要正确评估这些P/SV偏移方法的精度和分辨率，就需要开发一种能够处理三维不连续地形和速度不均匀的合成地震记录方法，其中将包括所有转换的震相和地表反射。将实施一种混合方法，该方法将使用射线理论将P波前传播到横跨不连续面和表面之间区域的有限差分网格。这些技术将应用于西南太平洋和加利福尼亚州东部的区域数据集。这些努力对于今天适当的数据集是非常有用的，对于拟议的美国阵列和类似项目将产生的数据集，这些努力将变得越来越重要。

Abstract for proposal EAR0106904 (PH # 45x)Title: High Resolution Imaging of Seismic Velocity DiscontinuitiesPI: Anne F. Sheehan, University of Colorado, BoulderSeismic estimates of existence and depth distribution of crust and mantle discontinuities are important for constraining models of composition, rheology, and temperature in the Earth. This project includes development, testing, and application of new methods for receiver function imaging. A Kirchhoff-style migration methodology which utilizes a point-scattering approach to handle nonplanar and laterally discontinuous interfaces has been developed. An uncertainty in this analysis is the biasing effects of three-dimensional discontinuity structure that could falsely project features into two-dimensional models. The migration inversion will be extended to three dimensions, and include back-scattered energy. Proper evaluation of the accuracy and resolution of these P/SV migration methods will require development of a synthetic seismogram method that can handle 3-D discontinuity topography and velocity heterogeneity and which will include all converted phases and surface reflections. A hybrid method will be implemented that will use ray theory to propagate a P wavefront to a finite difference grid that will span the region between the discontinuities and the surface. These techniques will be applied to regional data sets from the southwest Pacific and eastern California. These efforts are of great utility with appropriate data sets today and will become increasingly important with data sets that will be generated by the proposed USArray and similar projects.