Seismic waveform tomography on continental scales based on the spectral-element and adjoint methods

基于谱元和伴随方法的大陆尺度地震波形层析成像

• 批准号: 73582572
• 负责人: Professor Dr. Hans-Peter Bunge, Ph.D.
• 金额: --
• 依托单位: Sektion Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/73582572?language=en
• 关键词: Seismic; waveform; tomography; continental; scales

Recent progress in numerical seismology and computer science enables today s seismologists to model elastic wave propagation through heterogeneous media routinely with high accuracy. This development suggests to go beyond the common data reduction (e.g. extracting travel times) and to analyse full waveforms for the purpose of high-resolution seismic tomography. Our research project is focused on the development of a full waveform inversion (FWI) technique for the detailed imaging of upper mantle structure and its application to the Australian continent. For this we propose (1) to compile a database of highquality waveform data for the Australian continent; (2) to design full waveform misfits in order to extract as much robust information as possible from the seismograms; (3) to employ a spectral-element method in conjunction with the adjoint method for the computation of tomographic images; (4) to assess the importance of correctly accounting for 3D Earth structure in general and for ocean-continent boundaries in particular, and (5) to compare the resolution capabilities of a FWI with those of classical ray tomographies. Key innovations of the FWI are that the forward modelling is accurate in media with lateral variations such as ocean-continent transitions. The synthetic waveforms and the resulting tomographic images can therefore be expected to be more realistic. Moreover, the amount of exploited information is significantly higher than in classical inversion methods based on ray or normal mode theory. Exploiting this wealth of information will lead to better constrained models of upper mantle structure with impact on the related geodynamic issues.

数值地震学和计算机科学的最新进展使当今的地震学家能够定期高精度地模拟弹性波通过异质介质的传播。这一发展建议超越常见的数据缩减（例如提取走时）并分析完整波形以实现高分辨率地震层析成像。我们的研究项目专注于开发用于上地幔结构详细成像的全波形反演（FWI）技术及其在澳大利亚大陆的应用。为此，我们建议（1）编制澳大利亚大陆高质量波形数据数据库； (2) 设计完整的波形失配，以便从地震图中提取尽可能多的稳健信息； (3)采用谱元法与伴随法相结合来计算断层图像； (4) 评估正确解释 3D 地球结构的重要性，特别是海洋-大陆边界的重要性，以及 (5) 将 FWI 的分辨率能力与经典射线断层扫描的分辨率能力进行比较。 FWI 的主要创新在于，正演模型在具有横向变化（例如海洋-大陆转变）的介质中是准确的。因此，合成波形和所得断层扫描图像预计会更加真实。此外，所利用的信息量明显高于基于射线或简正模理论的经典反演方法。利用这些丰富的信息将产生更好的上地幔结构约束模型，并对相关的地球动力学问题产生影响。