Collaborative Research: Incorporating SPECFEM3D numerical seismograms in the Global CMT Project

合作研究：将 SPECFEM3D 数值地震图纳入全球 CMT 项目

• 批准号: 2218793
• 负责人: Goran Ekstrom
• 金额: $ 25.2万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2218793&HistoricalAwards=false
• 关键词: Collaborative; Research; Incorporating; SPECFEM3D; numerical

This research will lay the groundwork for improvements in the scientific description of earthquakes, benefitting researchers in earthquake statistics, seismic tomography, seismic hazard, and seismic discrimination, as well as tectonic interpretation and analysis. This is the first step towards making the results of complex and expensive numerical calculations available for multiple applications and a wide range of users. This work focuses on demonstrating the feasibility of the methodology, but the database and method will be valuable for any research requiring accurate predictions of the global seismic wavefield from an arbitrary earthquake at any location without expensive computation. Two graduate students will be trained in research at the nexus of earthquake science, theoretical seismology, and computational Earth science.This two-year, focused effort will (1) develop a new method for calculating, storing, and accessing high-fidelity long-period synthetic seismograms for state-of-the-art 3D tomographic models of the Earth, and (2) incorporate these seismograms in the earthquake analysis of the Global Centroid-Moment-Tensor (CMT) Project. Currently, the CMT synthetic seismograms are calculated using modern 3D Earth models, but accuracy is limited by the validity of the path-average approximation for mode summation and surface-wave ray theory, inexact predictions of the amplitude and polarization of ground motion, and other unmodeled effects, bias retrieved earthquake parameters. The incorporation of higher-fidelity synthetic seismograms in the CMT analysis will improve the characterization of seismic sources and remove concerns about a key source of uncertainty and bias. The team will adapt the spectral-element wave-equation solver SPECFEM3D_GLOBE to generate a database of kernel seismograms on a global grid of hypocenters, for a large set of station locations, using source-receiver reciprocity to speed up the calculation. Kernel seismograms on the grid will be organized and stored in a format that facilitates rapid access to a particular source region and the stations of the Global Seismographic Network. Kernel seismograms for an arbitrary centroid location will be efficiently calculated by spatial interpolation, in a manner that matches the accuracy of the full forward calculation. The CMT code will be modified to ingest the interpolated SPECFEM3D_GLOBE seismograms and testing will allow the assessment of success of the approach and method. The Princeton numerical seismology group and Lamont earthquake-analysis group will jointly evaluate the approach and fidelity of the waveform interpolation, develop practical formats for accessing the (massive) database of global waveforms, and assess the success of these developments.This project is jointly supported by the Geophysics and Instrumentation and Facilities programs in the Division of Earth Sciences. It is also co-funded by a collaboration between the Directorate for Geosciences and Office of Advanced Cyberinfrastructure to support AI/ML and open science activities in the geosciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项研究将为改进地震的科学描述，使研究人员在地震统计，地震层析成像，地震危害和地震歧视以及构造解释和分析方面奠定基础。这是使复杂且昂贵的数值计算结果的第一步可用于多个应用程序和广泛的用户。这项工作重点是证明该方法的可行性，但是数据库和方法对于任何需要从任何位置的任意地震中的全球地震波场进行准确预测的任何研究都将是有价值的，而无需昂贵的计算。两名研究生将接受地震科学联系，理论地震学和计算地球科学的研究培训。这两年的重点努力将（1）开发一种用于计算，存储和访问高效长期长期合成图的新方法质心张量（CMT）项目。目前，使用现代3D地球模型计算了CMT合成地震图，但是准确性受模式求和路径平均近似的有效性的限制，对于地面运动的振幅和振幅振幅和其他未模拟效应，偏见检索地震参数。在CMT分析中，将高保真综合地震图的结合纳入将改善地震源的表征，并消除对关键不确定性和偏见的关注。该团队将适应光谱元件的波动求解器specfem3d_globe，以使用源代码互互互相互惠速度加快计算，以在全球次数上生成内核地震图的数据库。网格上的内核地震图将以促进进入特定源区域和全球地震网络站点的快速访问的格式进行组织和存储。任意质心位置的内核地震图将通过空间插值有效地计算，与完整正向计算的准确性相匹配。 CMT代码将进行修改以摄取插值SpecFem3D_Globe地震图和测试将允许评估方法和方法的成功。普林斯顿的数值地震学组和拉蒙特地震 - 分析小组将共同评估波形插值的方法和忠诚度，开发用于访问全球波形（大型）数据库的实用格式，并评估这些发展的成功。这些项目的成功是由地球物理学和仪器和设施计划共同支持的。它也由地球科学局与高级网络基础设施办公室之间的合作共同资助，以支持AI/ML和地球科学中的开放科学活动。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和广泛影响的评估来通过评估来支持的。