To achieve the main goal of ENDGAME, we performed more than 200 experiments of jet flow dynamics with a shock-tube apparatus in combination with Schlieren shadow photography. Schlieren shadow photography is a technique used to visualize density contrasts within fluids (especially low-density fluids, such as gases, Fig. 1). Experiments were performed with a cylindrical shock-tube, where pressurized gas (with different amount of particles and/or viscous liquids) has been injected into the pipe to simulate gas flow during the first instant of an explosive eruption (Fig. 2). By using Schlieren shadow photography and high speed cameras, we were able to capture the propagation of shock waves and acoustic waves in the atmosphere during the experiments, which were not visible otherwise. We also deployed a several acoustic sensors and a pressure sensor at the vent of the pipe, to record both the acoustic signals and the pressure evolution during the experiments (Fig. 3). These provided us a unique multiparametric dataset of jet flow dynamics. Preliminary results on experiments performed with pressurized gas only have been published in a scientific journal (Spina et al., 2023), and other manuscripts are currently in preparation.
We also designed and developed a new experimental setup, consisting of a 2D planar shock-tube apparatus obtained using two parallel glass sheets. With these type of experiments we wanted to describe and characterize explosive eruptions from fissure vents. The design and development of the 2D apparatus was a difficult task, but workshop technicians at the host institution were able to provide us with the 2D shock tube apparatus before the end of the project, allowing us to perform some preliminary experiments with it.
The multiparametric datasets we collected with our experiments, combined with numerical simulations and field observations, will be extremely useful in unravelling jet flow dynamics during explosive eruptions at basaltic volcanoes. For this reason, to better understand the dynamics of jet flow occurring during our laboratory experiments, and more in general during explosive eruptions, we performed numerical simulations with a magma ascent model. The numerical model is a multidimensional transient model of two-phase flow, which has been used to replicate some of the laboratory experiments performed with the cylindrical shock-tube. Overall, we found a good agreement between jet flow dynamics observed from the experiments compared with that simulated with the numerical code (Fig. 4). We can reproduce the propagation of the shock wave in the atmosphere when the pressurized gas exits the tube, and the formation of the vortex ring and of the shock cells due to supersonic jet flow.
Furthermore, we performed numerical simulations investigating how different particle size, flatness and elongation affect magma ascent dynamics. As test case scenarios, we simulated explosive activity at Etna and Stromboli, and the results of this investigation will be the focus of another manuscript, which is currently under preparation.
To collect data from an active volcano during explosive activity, two field campaigns at Stromboli volcano were conducted. Stromboli is an active volcano, which produces persistently mild explosive activity, approximately every 15-30 minutes. Sometimes, however, is able to generate highly explosive eruptions, with an ash cloud that can reach up to several kilometres in height. We collected multiparametric data using simultaneously a high speed camera, a thermal camera, and a microphone during mild explosive activities (Fig. 5). Analyses of the data are still on-going, but having multiparametric datasets of real explosive activities which can be compared with laboratory experiments and numerical modelling will provide a great opportunity to better understand explosive dynamics at Stromboli volcano, and in general at basaltic volcanoes.
Results obtained within ENDGAME have been exploited in many ways. Achievements of the project have been presented in several national and international conferences, during seminars, and with scientific publications. Furthermore, some of the activities and results obtained during the course of the project have been illustrated in the website of the ENDGAME project (
https://progetti.ingv.it/it/endgame(odnośnik otworzy się w nowym oknie)). Finally, to reach a more general audience, social media accounts (on Instagram and X, @endgame_msca) have been also created and populated with dedicated contents.
