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Dyke-induced seismicity: depth-dependent acoustic emissions and strain in rock deformation experiments

Matías Clunes 1,3, Philip Benson2,3, Carmen Solana1,3

  • Affiliations: 1School of the Environment and Life Sciences, University of Portsmouth, Portsmouth, UK; 2Department of Earth Sciences, LMU München, Germany; 3 Project FEVER, UK Research and Innovation

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 255

  • Programme No: 2.4.33

  • Theme 2 > Session 4

Abstract

Understanding dyke intrusions and related seismicity is a key tool in forecasting volcanic eruptions. Modified triaxial experiments were conducted on brittle volcanic rocks using heated and pressurized plexiglass as an analog for rhyolitic magma. Experiments simulated depths of 1, 2 and 3 km respectively, in each case inducing tensile failure in the host rock through conduit overpressure. Acoustic Emission (AE) monitoring captured microseismic activity (a proxy for field scale earthquake activity), while radial strain measurements linked AE observations to fracture dynamics. Preliminary results reveal complex depth-dependent mechanical and AE behaviors: All experiments showed radial dilation before failure. At 1 km, exponential AE increase precedes tensile failure, followed by an AE peak (50/10 s), a gradual pressure drop from 6 to 5 MPa and abrupt strain increase. At 2 km, minor AE activity precedes failure, followed by a peak of 78 AE/10 s, correlated with a sharp pressure drop from 9.5 to 1.5 MPa and ~2% strain increase. At 3 km, few high-energy AE events (8/10 s) accompany a 1 MPa pressure drop and no strain changes, followed by gradual pressure increase, immediately followed by a large (main) drop of 9 MPa with 180 AE/10 s and ~3% strain increase. Post-failure AE activity diminished significantly at greater depths. Our experiments show that greater conduit overpressures are required to induce tensile failure at depth, and how crustal depth influence seismic activity related to dyke initiation and propagation, providing useful insights to understand precursor activity in active volcanoes.