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New Constraints on Seismic Source Type Evident in 3D Waveform Inversions, Application to Remote Historical Nuclear Explosions in Western China

Description: 

Using historical nuclear tests from Western China, we compare the performance of legacy 1D and new 3D Earth models in scenarios involving sparse station coverage, low signal-to-noise ratio, and complex local geology.  In such challenging circumstances, conventional best-fitting inversions fail to reliably constrain moment tensor source type.  Detailed uncertainty analysis using the Moment Tensor Uncertainty Quantification (MTUQ) software package highlights the pronounced nonuniqueness of conventional 1D inversions, with error bars spanning nearly the entire space of source types.   By using 3D Earth models and jointly inverting multiple data types, however, we show that well-constrained solutions are possible. This enhanced resolution allows for additional experimentation with source wavelet selection and moment magnitude analysis.  These results highlight the complimentary character of body waves, Rayleigh waves, Love waves, and first motions for constraining source type, and point to the emergence of entirely new constraints in 3D inversions.  Particularly striking are new Rayleigh wave constraints, which persist even with highly lopsided stations distributions and thus appear distinct from radiation pattern constraints that tend to dominate 1D inversions, and new Love wave constraints on moment tensor trace, which are completely absent from 1D inversions.

Session: Advancements in Forensic Seismology and Explosion Monitoring - III

Type: Oral

Date: 4/17/2025

Presentation Time: 02:00 PM (local time)

Presenting Author: Jonas

Student Presenter: No

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