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Abstract:
We present the second generation of the Collaborative Seismic Earth Model (CSEM), a multi-scale global tomographic Earth model that continuously evolves via successive regional and global-scale refinements. Harvesting the distributed human and computation power across the tomography community, the CSEM framework allows to systematically build on previously accumulated knowledge. This is achieved by providing the current version of the CSEM as a starting model for regional tomographic studies and incorporating these findings into the following version of the CSEM. <br><br>The CSEM hosts 21 refinements from full seismic waveform inversion with diverse regional scales ranging from hundreds of km to entire continents. Noticeable changes since the first generation include detailed local updates for the Central Andes, Iran, South-east Asia, and the Western US, and continental scale refinements for Africa and Asia. A global long-period model improves the resolution int areas that have not been covered by other refinements. The current CSEM combines three-component waveform data from 1,637 events and over 700,000 unique source-receiver pairs across all regional updates.<br><br>To complete the model, we perform a global full waveform inversion over multiple period bands to a minimum period of 50 s. With this approach we ensure waveform prediction across regional model boundaries and that the resolved Earth structure is part of a single coherent model. We demonstrate seismic waveform prediction of minimum periods of 50 s on the global scale and for 20 s to 30 s in selected areas. Active participation in the project is encouraged.
