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Determination of discontinuous seismic structure using waveform inversion

利用波形反演确定不连续地震结构

基本信息

批准号：
14540393
负责人：
GELLER Robert J.
金额：
$ 2.05万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540393/
关键词：
Earth structure Seismic discontinuity Synthetic seismograms Direct Solution Method Optimally accurate operator Anisotropy 浅発地震凸凹構造 angular order

项目摘要

The purpose of this research project was to analyze broadband seismic data to determine the fine structure of the Earth's interior., including seismic discontinuities. Progress towards this goal requires accurate and efficient methods for calculating synthetic seismograms and their partial derivatives, and for conducting inversion for seismic structure models. We achieved the following progress in these areas.Forward calculations : (1)In many previous numerical methods the accuracy of synthetic seismograms seriously degraded if the seismic source was not located exactly at a node of the computational grid. We have developed methods that allow calculations for arbitrarily located seismic sources with the same accuracy as for seismic sources at grid points. (2)The accuracy of many previous finite difference schemes was seriously degraded if lithological discontinuities did not coincide exactly with the computational grid. We developed optimally accurate numerical operators for elements containing inter-node lithological discontinuities.Inversion : (1)We developed an accurate scheme for a finite perturbation to a lithological discontinuity. (2)In most global studies seismic sources and observatories are not uniformly distributed. We developed a weighting scheme to account for this uneven distribution when carrying out seismic inversion, and applied it to an observed dataset to obtain an unbiased 3-D Earth model.

该研究项目的目的是分析宽带地震数据，以确定地球内部的精细结构。包括地震不连续性实现这一目标的进展需要准确和有效的方法来计算合成地震图及其偏导数，并进行地震结构模型的反演。在这些方面取得了如下进展：（1）在以往的数值方法中，如果震源不精确地位于计算网格的某个节点上，合成地震记录的精度会严重下降。我们已经开发出的方法，允许计算任意位置的地震源与地震源在网格点相同的精度。（2）当岩性不连续面与计算网格不完全重合时，以往的有限差分格式的精度会严重下降。反演：（1）对岩性不连续面的有限摄动问题，建立了一个精确的数值计算格式。(2)In大多数全球研究的震源和观测站分布不均匀。我们开发了一个加权方案，以考虑这种不均匀的分布时，进行地震反演，并将其应用到观测数据集，以获得一个公正的3-D地球模型。