TY - JOUR
T1 - Constitutive Laws for Etnean Basement and Edifice Lithologies
AU - Bakker, Richard R.
AU - Violay, Marie E.S.
AU - Vinciguerra, Sergio
AU - Fazio, Marco
AU - Benson, Philip M.
PY - 2019
Y1 - 2019
N2 - The mechanical dynamics of volcanic systems can be better understood with detailed knowledge on strength of a volcanic edifice and subsurface. Previous work highlighting this on Mt. Etna has suggested that its carbonate basement could be a significant zone of widespread planar weakness. Here, we report new deformation experiments to better quantify such effects. We measure and compare key deformation parameters using Etna basalt, which is representative of upper edifice lava flows, and Comiso limestone, which is representative of the carbonate basement, under upper crustal conditions. These data are then used to derive empirical constitutive equations describing changes in rocks strength with pressure, temperature, and strain rate. At a constant strain rate of 10-5 s-1 and an applied confining pressure of 50 MPa, the brittle-to-ductile transitions were observed at 975 °C (Etna basalt) and 350 °C (Comiso limestone). For the basaltic edifice of Mt. Etna, the strength is described with a Mohr-Coulomb failure criterion with μ ~ 0.704, C = 20 MPa. For the carbonate basement, strength is best described by a power law-type flow in two regimes: a low-T regime with stress exponent n ~ 5.4 and an activation energy Q ~ 170.6 kJ/mol and a high-T regime with n ~ 2.4 and Q ~ 293.4 kJ/mol. We show that extrapolation of these data to Etna's basement predicts a brittle-to-ductile transition that corresponds well with the generally observed trends of the seismogenic zone underneath Mt. Etna. This in turn may be useful for future numerical simulations of volcano-tectonic deformation of Mt. Etna, and other volcanoes with limestone basements.
AB - The mechanical dynamics of volcanic systems can be better understood with detailed knowledge on strength of a volcanic edifice and subsurface. Previous work highlighting this on Mt. Etna has suggested that its carbonate basement could be a significant zone of widespread planar weakness. Here, we report new deformation experiments to better quantify such effects. We measure and compare key deformation parameters using Etna basalt, which is representative of upper edifice lava flows, and Comiso limestone, which is representative of the carbonate basement, under upper crustal conditions. These data are then used to derive empirical constitutive equations describing changes in rocks strength with pressure, temperature, and strain rate. At a constant strain rate of 10-5 s-1 and an applied confining pressure of 50 MPa, the brittle-to-ductile transitions were observed at 975 °C (Etna basalt) and 350 °C (Comiso limestone). For the basaltic edifice of Mt. Etna, the strength is described with a Mohr-Coulomb failure criterion with μ ~ 0.704, C = 20 MPa. For the carbonate basement, strength is best described by a power law-type flow in two regimes: a low-T regime with stress exponent n ~ 5.4 and an activation energy Q ~ 170.6 kJ/mol and a high-T regime with n ~ 2.4 and Q ~ 293.4 kJ/mol. We show that extrapolation of these data to Etna's basement predicts a brittle-to-ductile transition that corresponds well with the generally observed trends of the seismogenic zone underneath Mt. Etna. This in turn may be useful for future numerical simulations of volcano-tectonic deformation of Mt. Etna, and other volcanoes with limestone basements.
KW - Comiso limestone
KW - constitutive laws
KW - Etna basalt
KW - experimental data
KW - rheological profile
KW - rock deformation
UR - http://www.scopus.com/inward/record.url?scp=85074347661&partnerID=8YFLogxK
U2 - 10.1029/2019JB017399
DO - 10.1029/2019JB017399
M3 - Article
AN - SCOPUS:85074347661
SN - 2169-9313
VL - 124
SP - 10074
EP - 10088
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 10
ER -