Abstract
Lava dome collapse hazards are intimately linked with their morphology and internal structure. We present new lava dome emplacement models that use calibrated rock strengths and allow material behaviour to be simulated for three distinct units: (1) a ductile, fluid core; (2) a solid upper carapace; and (3) disaggregated talus slopes. We first show that relative proportions of solid and disaggregated rock depend on rock strength, and that disaggregated talus piles can act as an unstable substrate and cause collapse, even in domes with a high rock strength. We then simulate sequential dome emplacement, demonstrating that renewed growth can destabilise otherwise stable pre-existing domes. This destabilisation is exacerbated if the pre-existing dome has been weakened following emplacement, e.g., through processes of hydrothermal alteration. Finally, we simulate dome growth within a crater and show how weakening of crater walls can engender sector collapse. A better understanding of dome growth and collapse is an important component of hazard mitigation at dome-forming volcanoes worldwide.
Highlights
Lava domes pose a significant hazard when they become unstable and collapse, generating rockfalls, debris avalanches and pyroclastic density currents (Calder et al, 2002)
We present a suite of models that (1) incorporate different material behaviours for the coherent and disaggregated solid portions of the dome, allowing for more complex morphologies and structures to be simulated; (2) calibrate the computational models to incorporate realistic rock strengths and assess the effect of rock strength on dome stability; (3) investigate the effect of sequential dome growth on dome stability; and (4) investigate crater wall strength as a controlling factor in dome stability
The Discrete Element Method (DEM) is pertinent for modelling lava dome emplacement and stability as it allows for the visualisation of localised strain within a lava dome that cannot be elucidated from satellite or photographic monitoring
Summary
Lava domes pose a significant hazard when they become unstable and collapse, generating rockfalls, debris avalanches and pyroclastic density currents (Calder et al, 2002). Lava dome hazards are highly dependent on dome morphology (Wang et al, 2015), which is predominantly determined by the structure and material properties (such as rock strength) of the dome, as well as the topographic structures that exist in the vicinity of the volcanic vent, e.g., pre-existing domes or crater geometry These topographic structures are vulnerable to alteration due to the efficient circulation of hydrothermal fluids (Byrdina et al, 2017; Ghorbani et al, 2018; Rosas-Carbajal et al, 2016), a process that can influence their material properties, including strength (Cecchi et al, 2004; del Potro and Hürlimann, 2009; Heap et al, 2019; Heap et al, 2021a; Reid et al, 2002; Voight and Elsworth, 1997). For a more complete understanding of dome stability hazards, one must consider dome structure, rock strength, and existing topographic features
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
