The Positive Feedback Loop of 3D Earth Structure and Earthquake Source Parameters
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Claire Doody
Lawrence Livermore National Lab
- Date & Time
- Location
- Hybrid In Person and Online-only seminar via Microsoft Teams
- Host
- Theresa Sawi
- Summary
Seismic wavespeed models are a key assumption in estimating earthquake source parameters. Conversely, earthquake source parameters are needed to create synthetic data for adjoint waveform tomography (AWT) modelling. In a case study of California and Nevada, we began by constructing an AWT model using source parameters from the Global Centroid Moment Tensor (GCMT) catalogue. To mitigate source errors at short periods, we use an intermediate version of the AWT model to calculate 3D Green’s functions for moment tensor inversion. We found that the inverted moment tensors improved waveform fits and double couple percentages for moderate magnitude (Mw 4.5-6.5) earthquakes. These improved moment tensor parameters are then used to improve synthetic waveform fits in our AWT workflow. The improved source mechanisms allow us to iterate the AWT model to shorter periods, producing a higher resolution model. We also explore the effects of using 3D models on moment tensor accuracy by testing a synthetic catalogue of moment tensors inverted using 1D and 3D Earth models in the Middle East. We show that considering 3D Earth structure improves moment tensor accuracy, particularly in regions with limited station coverage.