Collaborative Research: Correlogram Migration of Scattered Teleseismic Body Waves

研究了一种利用散射体波相关图偏移成像地球反射率分布的新方法。 为地震勘探而发展的相关偏移方法正被推广到利用地震体波对密集接收器阵列下的地壳和上地幔结构成像。这些波包括P到SV和P到P表面反射相，以及其他直接和表面散射相。 结果是每个散射波在记录阵列下方的反射率分布的图像。 现有的利用接收函数的横向变化结构成像方法大多采用直接转换的P波到SV波来进行地下照明。 鬼反射的相关成像提供了与P到SV透射波的分辨率互补的分辨率。 使用相关图迁移的不同阶段的横向变化的介质成像使用微重力阵列数据的实用性的问题正在解决。 此外，相关图偏移的局限性作为数据质量，接收器间距和使用的地震数据类型的函数正在调查。由于实际的叠前阵列配置会产生一些混叠效应，一种新的对这些效应不太敏感的类波束偏移算法，称为波路径偏移，正在被测试用于叠前阵列数据的成像。目前正在使用Wasatch Front的不同微阵列配置对微阵列数据的相关图迁移进行测试。 这项研究的意义是开发新的成像方法的横向变化的结构使用的反射波数据，其中概括接收函数成像，包括转换以及鬼反射。相关图成像对于密集的地震台网是最有效的。

A new methodology for the imaging of the earth's reflectivity distribution by correlogram migration of scattered teleseismic body waves is being investigated. The correlation migration methods developed for applications in seismic exploration are being extended to the imaging of crustal and upper mantle structure beneath a dense receiver array using teleseismic body waves. These waves include P to SV and P to P surface reflected phases, in addition to other direct and surface scattered phases. The result is an image of the reflectivity distribution beneath the recording array for each of the scattered waves. The current imaging methods using receiver functions for laterally varying structure mostly use directly converted P to SV arrivals for subsurface illumination. Correlation imaging of ghost reflections provides complementary resolution to that of P to SV transmitted waves. Questions concerning the practicality of using correlogram migration of different phases for the imaging of laterally varying media using teleseismic array data are being addressed. Also, the limitations of correlogram migration as a function of data quality, receiver spacing and type of teleseismic data used are being investigated. Since for practical teleseismic array configurations, some aliasing effects will result, a new beam-like migration algorithm, call wavepath migration, which is less sensitive to these effects, is being tested for the imaging of teleseismic array data. The correlogram migration of teleseismic data is being tested using different teleseismic array configurations across the Wasatch Front. The significance of this research is the development of new imaging methods for laterally varying structure using teleseismic data, which generalizes receiver function imaging to include converted as well as ghost reflections. Correlogram imaging is most effective for dense seismic networks.