{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T09:38:00Z","timestamp":1786441080484,"version":"build-2736575974"},"reference-count":41,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T00:00:00Z","timestamp":1786406400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"CO2CRC Limited"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Passive distributed acoustic sensing (DAS) is an attractive tool for monitoring geological CO2 storage, but its dense, continuous recordings create a data-volume problem: a multi-month, multi-well archive yields enormous numbers of detector triggers, of which confirmed seismic events form a vanishingly small fraction, and conventional supervised classification is ill-posed when labels remain scarce and the negative class undefined because the non-event population is open-ended and spans noise families that vary over time and between wells. We present Argus, a sparse-label machine-learning workflow that converts continuous DAS recordings into a reproducible, auditable catalogue of event candidates. A deterministic front end reduces the archive to comparable trigger objects, each described by a 67-feature interpretable representation of its two-dimensional time\u2013channel character (e.g., duration and channel span, detector-mask morphology, apparent moveout, inter-channel waveform coherence, and spectral shape); a retrieval-first machine-learning layer then ranks these triggers by their similarity, in this interpretable feature space, to a small seed catalogue of independently confirmed events, within an iterative human-in-the-loop process that introduces local supervised noise-rejection gates only for recurrent artefact families once they have been labelled. Applied to the CO2CRC Otway Stage 4 dataset\u2014120 days of recordings on two wells, comprising roughly 23 TB and 14.14 million raw triggers\u2014the workflow expanded a 39-event seed catalogue into 631 analyst-reviewed events, demonstrating complementarity with an independent template-matching analysis: two additional induced-event candidates were recovered, one within the CRC4 template-matching coverage and one on CRC7 during a CRC4 data gap. The induced-event class itself grew only from four to six candidates, and its counts are reported as a reviewed lower bound rather than a complete census. The result is a provenance-preserving, conservatively interpreted event inventory rather than an opaque classifier output, an outcome aligned with the reproducibility and audit requirements of CO2 storage assurance.<\/jats:p>","DOI":"10.3390\/s26165084","type":"journal-article","created":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T09:11:16Z","timestamp":1786439476000},"page":"5084","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Argus: A Sparse-Label Machine-Learning Workflow for Passive DAS Seismic Catalogue Expansion in CO2 Storage Monitoring\u2014Application to the CO2CRC Otway Stage 4 Dataset"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-9429-8379","authenticated-orcid":false,"given":"Ilgiz","family":"Almukhametov","sequence":"first","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Olivia","family":"Collet","sequence":"additional","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2752-3528","authenticated-orcid":false,"given":"Boris","family":"Gurevich","sequence":"additional","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5741-8091","authenticated-orcid":false,"given":"Roman","family":"Isaenkov","sequence":"additional","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1484-6405","authenticated-orcid":false,"given":"Pavel","family":"Shashkin","sequence":"additional","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8456-7391","authenticated-orcid":false,"given":"Konstantin","family":"Tertyshnikov","sequence":"additional","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mikhail","family":"Vorobev","sequence":"additional","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5058-4348","authenticated-orcid":false,"given":"Nepomuk","family":"Boitz","sequence":"additional","affiliation":[{"name":"Division of Geophysics, Freie Universit\u00e4t Berlin, Malteserstr. 74-100, 12249 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2555-6860","authenticated-orcid":false,"given":"Roman","family":"Pevzner","sequence":"additional","affiliation":[{"name":"Centre for Exploration Geophysics, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"325","DOI":"10.2113\/gselements.4.5.325","article-title":"CO2 sequestration in deep sedimentary formations","volume":"4","author":"Benson","year":"2008","journal-title":"Elements"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Ringrose, P. 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