Geomechanical Properties of Volcanic Materials

Volcanic materials encompass a spectrum of rock types—from dense lavas and intrusive bodies to highly porous tuffs and fragmental pyroclastics—each exhibiting distinct mechanical and petrophysical characteristics. Porosity, reflecting the proportion of void space, and permeability, governing fluid flow, are primary controls on strength, deformability and stability of volcanic edifices. Microstructural features such as vesicle size, connectivity and microcrack networks further modulate mechanical response under varying temperature, pressure and fluid-chemistry conditions. Hydrothermal alteration can precipitate mineral infill, reducing permeability and altering stiffness, while thermal stressing and cyclic loading influence fracture toughness, tensile strength and elastic moduli. Laboratory deformation experiments reveal transitions from brittle failure, marked by shear fracturing and permeability increases, to ductile compaction and cataclastic pore collapse with porosity and permeability decline. These geomechanical insights underpin volcanic-hazard assessments, slope-stability analyses and the design of geothermal exploitation schemes, highlighting the need to integrate microstructural characterisation, in situ monitoring and numerical modelling for robust prediction of volcanic behaviour.

Research from Nature Portfolio

Recent studies have demonstrated that acid-sulphate hydrothermal alteration within lava domes can reduce permeability by multiple orders of magnitude, promoting pore-pressure build-up sufficient to fragment dome material and trigger explosive eruptions. Parallel work on fractured volcanic cores has quantified how macro-fractures amplify both permeability and its sensitivity to effective pressure, yielding generalised relationships to predict fluid transmissivity in intact and fractured rocks. Together, these findings establish quantitative frameworks linking alteration-driven permeability reduction and fracture-enhanced flow pathways to volcanic instability and hazard potential.

Geomechanical Properties of Volcanic Materials publication trend

The graph below shows the total number of articles in geomechanical properties of volcanic materials across all publications each year (not limited to Nature Index journals).

Technical terms

Porosity: Fraction of a rock’s volume occupied by voids or pores.

Permeability: Measure of a rock’s ability to transmit fluids through connected pore networks.

Uniaxial Compressive Strength (UCS): Maximum axial stress a rock sample can sustain under compression before failure.

Hydrothermal alteration: Chemical transformation of minerals by hot fluids, often altering strength and porosity.

Vesicularity: Abundance and size distribution of gas-formed bubbles (vesicles) in volcanic rock.

Cataclastic deformation: Inelastic compaction involving crushing and collapse of pore spaces under stress.

References

1. Hydrothermal alteration and physical and mechanical properties of rocks in a volcanic environment: A review. Earth-Science Reviews (2024).
2. Porosity, strength, and alteration – Towards a new volcano stability assessment tool using VNIR-SWIR reflectance spectroscopy. Earth and Planetary Science Letters (2023).
3. Compaction and Permeability Evolution of Tuffs From Krafla Volcano (Iceland). Journal of Geophysical Research: Solid Earth (2024).
4. The mechanical behaviour and failure modes of volcanic rocks: a review. Bulletin of Volcanology (2021).
5. The permeability of fractured rocks in pressurised volcanic and geothermal systems. Scientific Reports (2017).
6. Hydrothermal alteration of andesitic lava domes can lead to explosive volcanic behaviour. Nature Communications (2019).