Linking gas and particle ejection dynamics to boundary conditions in scaled shock-tube experiments

• DOI: 10.1007/s00445-021-01473-0
• Publication Date: 2021-07-20T07:03:26Z
• Authors: Valeria Cigala; Ulrich Kueppers; Juan José Peña Fe...; Donald B. Dingwell
• Keywords: Overpressure; Particle (ecology); Strombolian eruption

Predicting the onset, style and duration of explosive volcanic eruptions remains a great challenge. While fundamental underlying processes are thought to be known, clear correlation between eruptive features observable above Earth's surface conditions properties in immediate subsurface is far from complete. Furthermore, highly dynamic nature inaccessibility events means that progress field investigation such slow. Scaled experimental investigations represent an opportunity study individual separately and, despite their nature, quantify them systematically. Here, impulsively generated vertical gas-particle jets were using rapid decompression shock-tube experiments. The angular deviation vertical, defined as "spreading angle", has been quantified for gas particles on both sides at different time steps high-speed video analysis. variables investigated 1) vent geometry, 2) tube length, 3) particle load, 4) size, 5) temperature. Immediately prior first above-vent observations, expansion accommodates initial overpressure. All inevitably start with particle-free phase (gas-only), which typically clearly visible due expansion-induced cooling condensation. We record spreading angle directly influenced by geometry gas-only phase. After some delay, whose length depends conditions, jet incorporates becoming jet. Below we how our affect temporal evolution these two phases (gas-only gas-particle) each As expected, always least large angle. latter positively correlated load negatively size. Such empirical experimentally derived relationships known can serve input parameterisation equivalent observations active volcanoes, alleviating circumstances where priori knowledge magma textures ascent rate, temperature overpressure and/or shallow plumbing system chronically lacking. generation parameterisations raises possibility detailed frequently erupting volcanoes might used elucidating parameters variability, all implications may have better defining hazard assessment.The online version contains supplementary material available 10.1007/s00445-021-01473-0.