Geological interpretations, earthquake source inversions and ground motion modeling, among other applications, require models that jointly resolve crustal and mantle structure. With the second generation of the Collaborative Seismic Earth Model (CSEM2), we present a global multi-resolution tomographic Earth model that serves this purpose. The model evolves through successive regional- and global-scale refinements. While the first generation aggregated regional models, with this study, we ensure consistency between all individual submodels, resulting in a model that accurately explains wave propagation across scales. Recent regional tomographic models were incorporated, comprising continental-scale inversions for Asia and Africa, as well as regional inversions for the Western US, Central Andes, Iran, and Southeast Asia. Across all regional refinements, over 793,000 source-receiver pairs contributed. Moreover, the long-wavelength Earth model (LOWE) introduces large-scale structures outside of pre-existing local refinements. A full-waveform inversion for global anisotropic P-and S-wave speed structure over a total of 194 iterations with a minimum period of 50 s on a large data set of 1 hr of waveform data from 2,423 earthquakes and over 6 million source-receiver pairs ensures that regional updates in the crust and uppermost mantle translate into updates of deeper, global-scale structure. To test the performance of CSEM2, we evaluate waveform fits between observed and synthetic seismograms at 50 s for an independent data set on the global scale, and on the regional scale for lower periods. We accurately simulate waveforms within and across regional refinements, maintaining the original resolution of the submodels embedded in the global framework.

中文翻译：

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协作地震地球模型：第 2 代


地质解释、地震源反演和地震动建模等应用需要共同解析地壳和地幔结构的模型。通过第二代协作地震地球模型 （CSEM2），我们提出了一个用于此目的的全球多分辨率层析地球模型。该模型通过连续的区域和全球规模的改进而发展。虽然第一代聚合了区域模型，但通过这项研究，我们确保了所有单个子模型之间的一致性，从而产生了一个可以准确解释波跨尺度传播的模型。最近的区域层析模型被纳入其中，包括亚洲和非洲的大陆尺度反演，以及美国西部、安第斯山脉中部、伊朗和东南亚的区域反演。在所有区域优化中，超过 793,000 个源-接收器对做出了贡献。此外，长波长地球模型 （LOWE） 引入了预先存在的局部细化之外的大规模结构。全局各向异性 P 波和 S 波速度结构的全波形反演，总共进行了 194 次迭代，最小周期为 50 s，在来自 2,423 次地震和超过 600 万对震源-接收器对的 1 小时波形数据的大型数据集上，确保地壳和最上部地幔的区域更新转化为更深、 全球规模的结构。为了测试 CSEM2 的性能，我们评估了全球尺度上独立数据集的 50 s 观测地震图和合成地震图之间的波形拟合，以及较低时期的区域尺度上的波形拟合。我们准确模拟区域优化内部和区域之间的波形，保持嵌入全球框架中的子模型的原始分辨率。