Fracture and compaction of andesite in a volcanic edifice

Bulletin of Volcanology
M J HeapT Reuschlé

Abstract

The failure mode of lava-dilatant or compactant-depends on the physical attributes of the lava, primarily the porosity and pore size, and the conditions under which it deforms. The failure mode for edifice host rock has attendant implications for the structural stability of the edifice and the efficiency of the sidewall outgassing of the volcanic conduit. In this contribution, we present a systematic experimental study on the failure mode of edifice-forming andesitic rocks (porosity from 7 to 25 %) from Volcán de Colima, Mexico. The experiments show that, at shallow depths (<1 km), both low- and high-porosity lavas dilate and fail by shear fracturing. However, deeper in the edifice (>1 km), while low-porosity (<10 %) lava remains dilatant, the failure of high-porosity lava is compactant and driven by cataclastic pore collapse. Although inelastic compaction is typically characterised by the absence of strain localisation, we observe compactive localisation features in our porous andesite lavas manifest as subplanar surfaces of collapsed pores. In terms of volcano stability, faulting in the upper edifice could destabilise the volcano, leading to an increased risk of flank or large-scale dome collapse, while compactant deformation...Continue Reading

References

Nov 30, 2004·Science·Alexander Gerst, Martha K Savage

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Citations

Mar 20, 2020·Bulletin of Volcanology·M ColombierD B Dingwell
Jan 16, 2019·Scientific Reports·Francesco ParisioThomas Nagel

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Methods Mentioned

BETA
lava
flows
lava flow
lavas

Software Mentioned

Google Earth TM
Google Earth

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