Broad-band ambient noise surface wave tomography

详细信息    Broad-band ambient noise surface wave tomography

• 出版日期：2007.
• 页数：1 online resource.
• 第一责任说明：Gregory David Bensen.
• 分类号：a631 ; a263
• ISBN：9780549315117(e-book) :

MARC全文

62h0045989 20131115144904.0 cr an |||||||| 131022s2007 a fsbm |000|0 eng | 3284458 9780549315117(e-book) : CNY371.35 NGL eng NGL a631 ; a263 Bensen, Gregory David. Broad-band ambient noise surface wave tomography [electronic resource] : technique development and application across the United States / Gregory David Bensen. 2007. 1 online resource. Description based on online resource; title from title page (viewed Oct. 22 2013) Thesis (Ph.D.)--University of Colorado at Boulder.bGeology, 2007. Includes bibliographical references. In recent years, it has been shown that surface wave signals can be extracted from high-quality empirical Green functions (EGF) obtained through cross-correlation of long ambient noise timeseries. Early work showed that Rayleigh wave components of EGFs could be created in a narrow period band under certain background noise characteristics. Such Rayleigh wave signals were used to develop shear wave tomography models of several geographic regions with unprecedented high resolution. However, questions remained regarding the robustness of these signals and their range of applicability. My work focuses on two problems. The first is researching the best method for computing, measuring and selecting high-quality EGFs. The second is to use this new technique to create a three-dimensional (3D) velocity model of the continental United States. Testing a variety of temporal and spectral normalization techniques yields an optimal method of creating EGFs. These signals are evaluated for robustness in a variety of noise environments effectively broadening the bandwidth from 7.5-20 s period to 6-100 s period. An automated dispersion measurement technique is presented as well as a preferred method of measurement selection and certain "best practices" are proposed for future study. Applying this method across the continental United States I develop Rayleigh and Love wave group and phase speed dispersion maps from 8-70 s period. The resulting set of dispersion maps possesses unprecedented high resolution and bandwidth for continental scale surface wave investigations and unites diverse tectonic regions into a coherent model. I invert the dispersion maps for a 3D shear velocity model with resolution from the surface to 150 km depth using a two-step procedure. First is a linearized inversion for the best fitting velocity model. Second is a Monte-Carlo re-sampling to develop an ensemble of models of sufficient quality and to generate uncertainty estimates at all points. The resulting velocity model allows identification of prominent features in the crust and mantle and sheds light on topics such as topographic compensation, crustal heterogeneity and radial anisotropy in the crust. Seismic waves. ; Imaging. ; Seismic prospecting. Electronic dissertations local. aInternet resource. aCN b010001 http://pqdt.bjzhongke.com.cn/Detail.aspx?pid=bXq1S9%2fTOPU%3d 010001 Bs2721 rCNY371.35 ; h1 bs1310