Fault-mediated magma propagation and triggered seismicity revealed by the 2022 São Jorge Azores unrest

Hicks, Stephen P., Gonzalez, Pablo J., Lomax, Anthony, Ferreira, Ana M.G. and Ramalho, Ricardo S. 2026. Fault-mediated magma propagation and triggered seismicity revealed by the 2022 São Jorge Azores unrest. Nature Communications 17 (1) , 3531. 10.1038/s41467-026-71668-6

	PDF - Supplemental Material Download (81kB)
	PDF - Published Version Download (17MB)
	PDF - Supplemental Material Download (17MB)

Abstract

Understanding failed volcanic eruptions is key to mapping magma plumbing and forecasting hazards. Faults and fractures guide magma, but their mechanisms remain unclear due to the lack of precise earthquake locations and limited 3-D fault mapping in volcanic regions. The triple-junction setting of the Azores Archipelago, where volcanic systems and seismogenic faults coexist, offers a natural laboratory to study fault–magma interactions. We analysed ~18,000 earthquakes relocated to high precision using onshore and ocean-bottom seismometers, combined with geodetic data and seismic autocorrelation imaging, during a failed 2022 eruption on São Jorge Island. A magmatic dike ascended rapidly and mostly aseismically from the upper mantle, intruding a crustal fault before stalling ~1,600 m below the surface. Seismicity indicates that magma branching and lateral fluid escape along the fault triggered an intense, months-long swarm with rotated focal mechanisms. This study demonstrates the dual role of faults in facilitating and arresting magma ascent.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Earth and Environmental Sciences
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/, Type: open-access
Publisher:	Nature Research
Date of First Compliant Deposit:	27 April 2026
Date of Acceptance:	26 March 2026
Last Modified:	27 Apr 2026 10:45
URI:	https://orca.cardiff.ac.uk/id/eprint/186653

Actions (repository staff only)

Edit Item