TY - JOUR
T1 - Fracturing around magma reservoirs can explain variations in surface uplift rates even at constant volumetric flux
AU - Biggs, J.
AU - Rafferty, T.
AU - Macha, J.
AU - Dualeh, E.W.
AU - Weber, G.
AU - Burgisser, A.
AU - Carroll, F.
AU - Hart, L.
AU - Rust, A.C.
AU - Gilbertson, M.
AU - Morand, A.
PY - 2024/8/1
Y1 - 2024/8/1
N2 - Many volcanoes show continuous but variable deformation over timescales of years to decades. Variations in uplift rate are typically interpreted as changes in magma supply rate and/or a viscoelastic response of the host rock. Here we conduct analogue experiments in the laboratory to represent the inflation of a silicic magma body at a constant volumetric flux, and measure the chamber pressure and resulting surface displacement field. We observe that dyke intrusions radiating from the magma body cause a decrease in the peak uplift rate, but do not significantly affect the spatial pattern of deformation or spatially averaged uplift rate. We identify 4 distinct phases: 1) elastic inflation of the chamber, 2) a gradual decrease in the rate of uplift and pressurisation, associated with the formation of visible cracks 3) propagation of a dyke by mode 1 failure at the crack tip and 4) a pressure decrease within the chamber. Phase 2 can be explained by either a) crack damage, which reduces the elastic moduli of the surrounding rock or b) magma filling pre-existing cracks. Thus these experiments provide alternative mechanisms to explain observed variations in uplift rate, with important implications for the interpretation of deformation patterns at volcanoes around the world.
AB - Many volcanoes show continuous but variable deformation over timescales of years to decades. Variations in uplift rate are typically interpreted as changes in magma supply rate and/or a viscoelastic response of the host rock. Here we conduct analogue experiments in the laboratory to represent the inflation of a silicic magma body at a constant volumetric flux, and measure the chamber pressure and resulting surface displacement field. We observe that dyke intrusions radiating from the magma body cause a decrease in the peak uplift rate, but do not significantly affect the spatial pattern of deformation or spatially averaged uplift rate. We identify 4 distinct phases: 1) elastic inflation of the chamber, 2) a gradual decrease in the rate of uplift and pressurisation, associated with the formation of visible cracks 3) propagation of a dyke by mode 1 failure at the crack tip and 4) a pressure decrease within the chamber. Phase 2 can be explained by either a) crack damage, which reduces the elastic moduli of the surrounding rock or b) magma filling pre-existing cracks. Thus these experiments provide alternative mechanisms to explain observed variations in uplift rate, with important implications for the interpretation of deformation patterns at volcanoes around the world.
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85196488237&partnerID=MN8TOARS
U2 - 10.1016/j.jvolgeores.2024.108129
DO - 10.1016/j.jvolgeores.2024.108129
M3 - Article (Academic Journal)
SN - 0377-0273
VL - 452
JO - Journal of Volcanology and Geothermal Research
JF - Journal of Volcanology and Geothermal Research
M1 - 108129
ER -