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Published August 2, 2021 | Submitted
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Bayesian framework for inversion of second-order stress glut moments: application to the 2020 M_w 7.7 Caribbean Earthquake


We present a fully Bayesian inverse scheme to determine second moments of the stress glut using teleseismic earthquake seismograms. The second moments form a low-dimensional, physically-motivated representation of the rupture process that captures its spatial extent, source duration, and directivity effects. We determine an ensemble of second moment solutions by employing Hamiltonian Monte Carlo and automatic differentiation to efficiently approximate the posterior. Our method explicitly constrains the parameter space to be symmetric positive definite, ensuring the derived source properties have physically meaningful values. The framework accounts for the autocorrelation structure of the errors and incorporates hyperpriors on the uncertainty. We validate the methodology using a synthetic test and subsequently apply it to the 2020 M_w 7.7 Caribbean earthquake. The second moments determined for this event indicate the rupture was nearly unilateral and relatively compact along-strike. The solutions from this inverse framework can resolve ambiguities between slip distributions with minimal a priori assumptions on the rupture process.

Additional Information

The copyright holder for this preprint is the author/funder. Published Online: Wed, 21 Jul 2021. This work was partially funded by the National Science Foundation's (NSF) Graduate Research Fellowships Program (GRFP) under grant number DGE-1745301. The teleseismic waveforms used in this study are from the Global Seismographic Network (GSN) operated by Scripps Institution of Oceanography (II: IRIS/IDA; https://doi.org/10.7914/SN/II) (Scripps Institution Of Oceanography, 1986) and the Albuquerque Seismological Laboratory (IU: IRIS/USGS; https://doi.org/10.7914/SN/IU) (Albuquerque Seismological Laboratory (ASL)/USGS, 1988). These waveforms and associated metadata used in this study were accessed through the IRIS Data Management Center (DMC). The centroid and moment tensor solution used in this study were obtained from Global Centroid Moment Tensor (gCMT) catalog (Dziewonski et al., 1981; Ekstrom et al., 2012) at https://www.globalcmt.org/. The synthetic waveforms used in this study were generated using the software Mineos, version 1.0.2 (Masters et al., 2011), available at https://geodynamics.org/cig/software/mineos/ through the Computational Infrastructure for Geodynamics (CIG). Figure 1 was generated using The Generic Mapping Tools (GMT), version 6 (Wessel et al., 2019), available at https://www.generic-mapping-tools.org/.

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