Collaborative Seismic Earth Model: Generation 2

We present the second generation of the Collaborative Seismic Earth Model (CSEM). The CSEM is a multi-scale global tomographic Earth model that evolves continuously through successive regional- and global-scale refinements. In the light of generally limited resources, the CSEM provides a framework for Earth model construction via a systematic group effort. It thereby takes advantage of the distributed human and computing power within the seismological community. Consecutively employing the current state of the CSEM as initial model, serves as the basic mechanism for regional refinements, which consistently harness previously accumulated knowledge.The second generation of the CSEM incorporates around 20 regional refinements from full seismic waveform inversion, ranging in scale from several tens of kilometres to the whole Globe. Since the first generation, the most noticeable changes include continental-scale refinements for Africa and China, as well as detailed local waveform inversions for the Central Andes and Iran. A global full-waveform inversion ensures that regional updates are in accord with whole-Earth structure. In its entirety, the current CSEM combines three-components waveform data from 1,637 events and over 700,000 unique source-receiver pairs. Minimum periods of the evaluated data vary between subregions of the multi-scale model, spanning from 55 seconds (South Atlantic) to 8 seconds (Iberian Peninsula and Western Turkey). In this contribution, we will present the CSEM updating scheme and parameterisation, as well as the current state of the model. This is also intended to encourage active participation in the project.