Fantastic fissure eruptions and where to find them: Insights from an experimental study

Eruptions like Kilauea (2018), Fagradalsfjall (2021), and La Palma (2021) are fed by dikes, that form elongated fissures, spanning hundreds to thousands of meters. While field, seismic, and geodetic data reveal the extensive lateral and vertical dimensions of dikes, fissure eruptions can rapidly become discontinuous and localize to discrete vents. Active vents may migrate, shut down, and reactivate during the initial eruption stages, adding complexity to hazard assessment and risk management. Thus, understanding the key factors governing fissure eruption dynamics is essential for forecasting the early evolution of future eruptions especially in populated areas that could potentially be affected.

We use an experimental setup of an artificial fissure to explore the thermal processes governing flow dynamics in fissures. In these experiments, we inject molten wax into a non-planar slot and monitor flow behavior with particle tracking and temperature measurements at the wax-wall interface. This setup offers flexibility in adjusting fissure width, geometry, wall temperature, and injection rate, with the ability to vary these parameters during a single experiment or keep them constant. Within the first few minutes of an experiment, we observe flow diverting from narrow, colder sections of the fissure to wider, warmer segments. Additionally, wax flow responds dynamically to obstacles such as cavities and blockages leading to interesting flow patterns and feedback effects.

These experiments combined with computational models and monitoring data, have the capability of being useful in assessing the predictability, or unpredictability, of fissure eruption evolution in early eruptive stages.