In this dataset we provide data for 6 experimental models of caldera collapse and subsequent resurgence monitored through geophysical sensors (a force or “impact sensor”, Piezotronics PCB 104 200B02 and a Triaxial piezoelectric accelerometer, Model 356B18). The analogue modelling experiments were carried out at the TOOLab (Tectonic Modelling Laboratory), which is a joint laboratory between the Istituto di Geoscienze e Georisorse of the Consiglio Nazionale delle Ricerche, Italy and the Department of Earth Sciences of the University of Florence.
The laboratory work that produced these data was partly supported by the European Plate Observing System (EPOS), by the Joint Research Unit (JRU) EPOS Italia and by the “Monitoring Earth's Evolution and Tectonics” (MEET) project (NextGenerationEU). Specifically, this work was performed in the frame of the DynamiCal project, funded by the 2° TNA-NOA call of the ILGE-MEET project.
This dataset provides data from 36 rapid decompression experiments performed in the Fragmentation Lab at Ludwig-Maximilians-Universität München (LMU, Munich, Germany) supporting the publication Schmid, M, Kueppers U, Cigala V, Sesterhenn J and Dingwell DB (202x) “Release characteristics of overpressurised gas from complex vents: implications for volcanic hazards”.
The experiments were aimed to constrain the influence of complex vent geometry on the instantaneous gas expansion in a shock-tube setup, mimicking impulsive volcanic explosions. They were performed at the following experimental conditions: 1) six vent geometries (conduit geometry always cylindrical), composed by 2 sets of inner geometry (cylindrical and 15° diverging) with inclined exit planes of 5, 15 or 30° slant angle, 2) constant temperature (25°C), 3) four starting overpressure scenarios (5, 8, 15, 25 MPa), and 4) two reservoir volumes (127.4 cm3, 31.9 cm3), achieved via variable conduit length, with Argon being used for the pressurization.
During the experiments the setup is incrementally pressurized. When the desired experimental pressure in the reservoir is reached, rapid decompression is triggered (Kueppers et al., 2006; Cigala et al., 2017), producing a starting jet of expanding gas. Expansion-induced cooling leads to condensation of the Argon jet, allowing for optical analysis of gas expansion dynamics using highspeed videos. Gas dynamics (jet spreading and jet inclination) were analysed and correlated to experimental variables.
The dataset includes movies of 29 analogue experiments performed to investigate the effects on dike propagation by the following imposed parameters: density ratio between host-rock and magma analogues, rigidity layering and density layering of the host medium, flow rate and topography. The purpose of the experiments is to define a hierarchy of all the parameters considered, by varying systematically each of them, comparing semi-quantitatively the variations on dike geometry and velocity.
Experimental setup
The experimental set-up consists of a 33 × 58 × 38.5 cm3 Plexiglas box and a peristaltic pump that injects water (magma analogue) into pig-skin gelatin (crustal analogue) alternatively from the bottom (Set 1) and the side of the box (Set 2).
The gelatin rheological properties are varied by mixing different concentrations of gelatin powder and NaCl. We refer to “rigidity layering” when the rigidity ratio (i.e. Young’s Modulus) between the upper and lower layer (Eu/El) is < or > 1, and to “density layering” when Eu/El ~ 1, but the two layers show different densities (i.e. the ratio between the density of the upper and lower layer, ρU/ρL). The experiments with topography are prepared by imposing a mold with gently inward dipping flanks (2.4° and 3.7°) on the opposite sides of the box separated by a 8 cm wide horizontal plain on the gelatin surface.
This configuration simulates the 2-D along-strike topography of the 2014 Bardarbunga intrusion (Iceland) and allows investigating the role of two opposite slopes on dike propagation. The topography profile dips parallel to the long side of the Plexiglas box (x axis in Figure 1 of Urbani et al. 2018). The flow rate has been changed between 0.079 and 0.435 ml/s. For the details about the model set-up, experimental results and interpretation refer to Urbani et al. (2018).
The time-lapse movies show the time evolution of the dike shape, in side and map view, of 29 out of 33 models presented in Urbani et al. (2018). It is recommended to open the films with the VLC media player. The time-lapse of each experiment is indicated in the bottom left corner.
A full list of files is given in “Experiments_Summary_2018-012.pdf” in which Set 1 (bottom injection) and Set 2 (lateral injection) experiments are indicated in red and blue color respectively. The same file also provides a summary of the boundary conditions imposed in each experiment. Tu and Tl indicate the thickness of the upper and lower layer respectively.