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方面的最新进展使当今的Seismologist能够以高精度通常以异质媒体的形式对弹性波传播进行建模。这一发展建议超越常见数据减少（例如提取旅行时间），并为高分辨率地震断层扫描的目的分析完整的波形。我们的研究项目侧重于开发完整的波形反演（FWI）技术，用于详细的地幔结构成像及其在澳大利亚大陆上的应用。为此，我们建议（1）为澳大利亚大陆编辑高质量波形数据数据库； （2）设计完整的波形错误，以便从地震图中提取尽可能多的鲁棒信息； （3）使用频谱元素方法与伴随方法一起计算层析成像图像； （4）评估一般，尤其是尤其是海洋界限的3D地球结构的重要性，（5）将FWI的分辨率与经典射线层表的分辨率功能进行比较。 FWI的关键创新是，在具有横向变化（例如大洋过渡）的介质中，正向建模是准确的。因此，可以期望合成波形和所得的断层扫描图像更现实。此外，被剥削的信息的量显着高于基于射线或正常模式理论的经典反转方法。利用这些丰富的信息将导致上层地幔结构的更好约束模型，并影响相关的地球动力学问题。