Bayesian regional moment tensor from ocean bottom seismograms recorded in the Lesser Antilles: Implications for regional stress field

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Lindner, Mike, Rietbrock, Andreas, Bie, Lidong ORCID: https://orcid.org/0000-0002-8130-7084, Goes, Saskia, Collier, Jenny, Rychert, Catherine, Harmon, Nicholas, Hicks, Stephen P. and Henstock, Tim and VioLA working group (2022) Bayesian regional moment tensor from ocean bottom seismograms recorded in the Lesser Antilles: Implications for regional stress field.

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Abstract

In this paper, we perform full-waveform regional moment tensor (RMT) inversions, to gain insight into the stress distribution along the Lesser Antilles arc. We developed a novel inversion approach, AmPhiB - Amphibious Bayesian, taking into account uncertainties associated with OBS deployments like the orientation of horizontal components and the high noise level. The inversion is conducted using a direct, uniform importance sampling of the fault parameters within a tree structure. We show that the alignment of the horizontal OBS components influences the obtained source mechanism when using standard least-squares (L2) RMT inversion schemes, resulting in systematic errors in the recovered focal mechanisms including high artificial CLVD contributions. AmPhiB reduces these CLVD components by nearly 60% and the aberration of the focal geometry as measured by the Kagan angle by around 40% relative to a standard L2 inversion. Subsequently, we obtain 45 (Mw > 3.8) regional MT solutions. Combining our new results with existing solutions, we subsequently analyze a total of 151 solutions in a FMC diagram and map them to the regional tectonic setting. We perform stress tensor inversions along the arc. On the plate interface, we observe a compressional stress regime and find evidence for upper-plate strike slip and normal fault behaviour in the north and a near arc-perpendicular extensional stress regime towards the south. A dominant slab perpendicular extensional stress regime is found in the slab at 100-200 km at the arcs center. We interpret this stress condition to be a result of slab pull varying along the arc due to partial slab detachment along previously hypothesized lateral slab tear near Grenada, at the southern end of the LA arc, leading to reactivation of preexisting structures around the subducted Proto-Caribbean ridge.

Item Type:	Article
Additional Information:	This preprint has been accepted for publication in Geophysical Journal International. Mike Lindner, Andreas Rietbrock, Lidong Bie, Saskia Goes, Jenny Collier, Catherine Rychert, Nicholas Harmon, Stephen P Hicks, Tim Henstock, the VoiLA working group, Bayesian regional moment tensor from ocean bottom seismograms recorded in the Lesser Antilles: implications for regional stress field, Geophysical Journal International, Volume 233, Issue 2, May 2023, Pages 1036–1054, https://doi.org/10.1093/gji/ggac494
Uncontrolled Keywords:	physics.geo-ph
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Geosciences
Related URLs:	http://arxiv.org/pdf/2206.05502v1
Depositing User:	LivePure Connector
Date Deposited:	16 Nov 2022 14:30
Last Modified:	07 Oct 2023 01:32
URI:	https://ueaeprints.uea.ac.uk/id/eprint/89889
DOI:

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