Can earthquake locations be improved for real-time monitoring? Revisiting the 1995 seismicity at Soufriere Hills Volcano, Montserrat

Eyles, Jade, Johnson, Jessica, Barclay, Jenni, Smith, Paddy and Miller, Victoria (2025) Can earthquake locations be improved for real-time monitoring? Revisiting the 1995 seismicity at Soufriere Hills Volcano, Montserrat. Seismica, 4 (1). ISSN 2816-9387

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Abstract

Volcanic earthquakes provide a wealth of information about the magmatic system. Monitoring volcanic seismicity is one of the primary methods used by volcano observatories globally, including at Soufri`ere Hills Volcano, Montserrat. Computed earthquake locations represent the optimal solution given the information available, and vary depending on the chosen location method and seismic velocity model, but rarely are these parameters tested for suitability in each region. We propose a new method that utilises synthetic earthquakes to evaluate whether the calculated hypocenters and their associated errors accurately represent the true source locations. We define this evaluation as a confidence parameter that highlights events we can 'trust'. By comparing several location methods and seismic velocity models for Montserrat we show the current setup is not optimal, and suggest an alternative location method. Analysis using new 'trusted' relocations focuses on four seismic clusters distal from Soufriere Hills in 1995. Our results highlight differences in hypocenters during this period, suggesting alternative interpretations of the distal seismicity. We propose a WNW dyke orientation supporting previous studies, and local fault complexes in the region. Overall, this paper highlights the importance of using a robust location method suitable for the region to ensure that calculated hypocenters are trustworthy and accurate. Use of sub-optimal methods can influence apparent spatial earthquake trends, impacting interpretations and our understanding of volcanic systems.

Item Type: Article
Additional Information: Data and code availability: The seismic catalogue used in this paper was provided by the Montserrat Volcano Observatory through a data agreement between J.E. and MVO. Data requests should be made to the Montserrat Volcano Observatory. Code used for real and synthetic hypocenter calculations was from the location methods Hypocenter and NonLinLoc. The Hypocenter program was used within the SEISAN software package which can be down-loaded at: https://www.geo.uib.no/seismo/SOFTWARE/-SEISAN/. The NonLinLoc software can be downloaded online at: http://alomax.free.fr/nlloc/index.html.The supplemental material provides additional im-ages relating to the velocity models, seismic stations and synthetic earthquake grid used for the synthetic testing. It includes a more comprehensive table of results from the synthetic testing and a full list of earth-quake hypocenters and corresponding errors for events used in this analysis. Funding information: J.E. was funded by NERC studentship NE/L002582/1. J.E. is currently funded by a Marie Curie Fellowship Grant.
Uncontrolled Keywords: geophysics,computers in earth sciences,3* ,/dk/atira/pure/subjectarea/asjc/1900/1908
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Groups > Geosciences
Depositing User: LivePure Connector
Date Deposited: 04 Jun 2025 14:30
Last Modified: 04 Jun 2025 14:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/99394
DOI: 10.26443/seismica.v4i1.1429

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