TY - CONF

T1 - Exploring the Impact of Fracture State on Volcanic Edifice Stability

AU - McGlynn, Nadia

AU - Harnett, Claire

AU - Villeneuve, Marlene C.

AU - Heap, M. J.

AU - Ní Nualláin, Kendra

PY - 2024

Y1 - 2024

N2 - Large-scale instability of volcanic edifices, which influences eruption style and timing,is dependent on the strength and fracture state of the composite rock. We can estimate therange of rock strength using the Geological Strength Index, which is based on the characterand distribution of fractures and discontinuities in a rock. This is usually based on qualitativeobservations of an in-situ rock mass. Small-scale strength of a rock sample can also beassessed in the laboratory via uniaxial compressive strength (UCS) testing. This small-scalestrength determined in the lab does not necessarily reflect the rock mass strength as it doesnot include the possibility of fractures in the rock mass.Numerical models have used different methods of upscaling these laboratory valuesto generate appropriate large-scale properties, such as bulk reduction of UCS values, andincorporation of natural fracture states that reduce the UCS. Appropriate strength of volcanicrock is important to create reliable, large scale models of volcanic instability. Here, we create2D models in Particle Flow Code, where we incorporate a discrete fracture network thatreproduces qualitative observations from GSI. We validate the relationship between GSI andUCS using modeled laboratory testing. Then we incorporate fracture networks intolarge-scale volcanic instability models to assess the impact of fracture distribution onvolcanic deformation.

AB - Large-scale instability of volcanic edifices, which influences eruption style and timing,is dependent on the strength and fracture state of the composite rock. We can estimate therange of rock strength using the Geological Strength Index, which is based on the characterand distribution of fractures and discontinuities in a rock. This is usually based on qualitativeobservations of an in-situ rock mass. Small-scale strength of a rock sample can also beassessed in the laboratory via uniaxial compressive strength (UCS) testing. This small-scalestrength determined in the lab does not necessarily reflect the rock mass strength as it doesnot include the possibility of fractures in the rock mass.Numerical models have used different methods of upscaling these laboratory valuesto generate appropriate large-scale properties, such as bulk reduction of UCS values, andincorporation of natural fracture states that reduce the UCS. Appropriate strength of volcanicrock is important to create reliable, large scale models of volcanic instability. Here, we create2D models in Particle Flow Code, where we incorporate a discrete fracture network thatreproduces qualitative observations from GSI. We validate the relationship between GSI andUCS using modeled laboratory testing. Then we incorporate fracture networks intolarge-scale volcanic instability models to assess the impact of fracture distribution onvolcanic deformation.

M3 - Poster

T2 - AGU Annual Meeting 2024

Y2 - 9 December 2024 through 13 December 2024

ER -