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This data repository contains electrical and seismic tremor measurements, thermal infrared imagery, atmospheric conditions and information on plume heights that were recorded and collected during the 2021 Tajogaite eruption on La Palma, Canary Islands, Spain. The 2021 Tajogaite eruption lasted from 19 September until 13 December 2021. The "data description" file provides more detailed information on each dataset and the way the data is formatted. The electrical data was recorded using a Biral Thunderstorm Detector BTD-200. This sensor was installed at two consecutive locations: BTD1 (28.635°N, 17.876389°W) recorded from 11-26 October 2021 and BTD2 (28.602365°N, 17.880475°W) recorded from 27 October 2021 until the end of the eruption. The volcanic tremor measurements were recorded at seismic station PLPI (28.5722°N, 17.8654°W), which was operated by the Instituto Volcanológico de Canarias. Here we provide the seismic tremor amplitudes within the Very Long Period (0.4-0.6 Hz) and the Long Period (1-5 Hz) frequency bands between 10 September and 20 December 2021. Thermal infrared videography of the explosive volcanic activity was done using an InfraTec HD thermal infrared (TIR) video camera. This camera was installed in El Paso (28.649361°N, 17.882279°W) and recorded almost continuously between 3-8 November 2021. Here we provide individual thermal infrared frames. Atmospheric conditions were obtained from weather balloon measurements at Güímar (station nr. 60018) on Tenerife, which were provided by the University of Wyoming, Department of Atmospheric Science (http://weather.uwyo.edu/). In addition, atmospheric data was collected from ground-based weather stations at El Paso and Roque de los Muchachos, which were operated by the State Meteorological Agency (AEMET) of Spain on La Palma. Information on the volcanic plume heights was obtained from both the Toulouse Volcanic Ash Advisory Center (https://vaac.meteo.fr/volcanoes/la-palma/) as well as the Plan de Emergencias Volcánicas de Canarias.
The described dataset resulted from a joint multidisciplinary measurement campaign in an agroforestry system in the Western Cape region in South Africa. Five participating institutions measured a range of environmental variables to characterise the influence of windbreak trees onto water fluxes, nutrient distribution and microclimate in the adjacent blackberry field. The dataset contains spatially collected soil characteristics, a soil profile description, time series of meteorological measurements as well as soil moisture and matric potential, information on soil hydraulic properties of the soil determined in the laboratory and windbreak characteristics and shape from a point cloud derived from terrestrial LiDAR scanning.
This data publication provides data from 39 experiments performed in 2021 to 2022 in the Gas-mixing lab at the Ludwig Maximilian University of Munich (Germany). The experiments were conducted to investigate the charging and discharging potential of decompressed soda-lime glass beads in varying enveloping gas composition and two different transporting gas species (argon and nitrogen). The experimental setup is a modified version of an apparatus first developed by Alidibirov and Dingwell (1996) and further modified by Cimarelli et al. (2014), Gaudin and Cimarelli (2019), and Stern et al. (2019) to enable the detection and quantification of discharges caused by the interaction of the discharging particles. The latest modifications enable the setup to perform experiments under gas-tight conditions allowing to test different atmospheric composition and pressure and to sample the gas within the particle collector tank. The sample material was ejected from the autoclave into the particle collector tank that is insulated from the autoclave and works as a Faraday cage. Discharges going from the jet to the nozzle were recorded by a datalogger. Additionally, the ejection of the decompressed material was recorded by a high-speed camera. The gas composition in the collector tank was changed from air to CO2 and a mixture of CO2 and CO. The particle collector tank was conditioned in two different modes: purging three times the tank with the desired gas composition or three times of purging and applying a vacuum in between. Analysis of gas samples taken from the collector tank before conducting the experiments revealed that in both cases a complete removal of the air was not achieved, but significantly reduced by the evacuation-purging method. Two gases were used to pressurize the sample within the autoclave: Nitrogen and Argon. The experimental results were compared to previous experiments (Springsklee et al., 2022a; Springsklee et al., 2022b).
These data files contain short periods of electrical data recorded at Stromboli volcano, Italy, in 2019 and 2020 using a prototype version of the Biral Thunderstorm Detector BTD-200. This sensor consists of two antennas, the primary and secondary antenna, which detect slow variations in the electrostatic field resulting from charge neutralisation due to electrical discharges. The sensor recorded at three different locations: BTD1 (38.79551°N, 15.21518°E), BTD2 (38.80738°N, 15.21355°E) and BTD3 (38.79668°N, 15.21622°E). Electrical data of the following explosions is provided (each in a separate data file): - Three Strombolian explosions on 12 June 2019 at 12:46:53, 12:49:27 and 12:56:10 UTC, respectively. - A major explosion on 25 June 2019 at 23:03:08 UTC. - A major explosion on 19 July 2020 at 03:00:42 UTC. - A major explosion on 16 November 2020 at 09:17:45 UTC. - A paroxysmal event at 3 July 2019 at 14:45:43 UTC. Each filename indicates the location of the BTD, the starting date and time of the file in UTC, and a short description of the three data columns inside the file (unixtime, primary, secondary). The first column provides the Unix timestamp of each data point, which is the time in seconds since 01/01/1970. All time is provided in UTC. The second column provides the measured voltage [V] recorded by the primary antenna. The third column provides the measured voltage [V] recorded by the secondary antenna.
This data publication provides data from 13 experiments performed in 2022 in the Gas-mixing lab at the Ludwig Maximilian University of Munich (Germany). The experiments were conducted to investigate the charging and discharging potential of material collected from a mud volcano from the Salton Sea (GPS-Data 33°12'2.7"N 115°34'41.4"W). The sample material was used in decompression experiments. The material was pressurized with argon gas instead of methane to assure safety conditions while running the experiments in the laboratory. The experimental setup is a modified version first developed by Alidibirov and Dingwell (1996) and further modified by Cimarelli et al. (2014); Gaudin and Cimarelli (2019); Stern et al. (2019) to enable the detection and quantification of discharges caused by the interaction of the discharging particles. The material was ejected from the autoclave into a Faraday cage, that is insulated from the autoclave and discharges going from the jet to the nozzle were recorded by a datalogger. Additionally, the eruption of the decompressed material was recorded by a high-speed camera. In the experiments, the influence of humidity and grain size distribution were tested. The influence of humidity was tested by using the material as wet as collected but also dried and milled and later exposed to varying but controlled humidity conditions. The grain size distribution was tested by mixing the dried and milled mud sample with 10, 50 and 90% of sea sand.
This data publication provides data from 96 experiments from 2020 to 2022 in the gas-mixing lab at the Ludwig-Maximilians-Universität München (Germany). The experiments were conducted to investigate the influence of grain size distribution, especially the influence of very fines [<10 µm] on the generation of experimental volcanic lightning (VL). The influence of grain size distribution was tested for three different materials. Experimental discharges during rapid decompression were evaluated by their number and their total magnitude. The three materials used in this study are a tholeiitic basalt (TB), industrial manufactured soda-lime glass beads (GB) and a phonolitic pumice from the lower Laacher See unit (LSB). The samples were sieved into several grain size fractions, and coarse and fines were mixed to test the influence of the added fines on the discharge behaviour. For the tholeiitic basalt, the coarse grain size fraction is 180-250 µm, for the glass beads 150-250 µm and for the phonolitic pumice, two coarse grain size fractions, 180-250 µm and 90-300 µm were tested. The experiments were carried out in a new experimental setup, a modification of the shock tube experiments first described by Alidibirov and Dingwell (1996) and its further modifications (Cimarelli et al., 2014; Gaudin & Cimarelli, 2019; Stern et al., 2019). A mixture of coarse and fine sample material is placed into an autoclave and continuously set under pressure with argon gas up to the desired decompression pressure (⁓10 MPa). Then, rapid decompression is initialized, and the sample material is ejected from the autoclave through a nozzle into a gas-tight particle collector tank. The particle collector tank is insulated from the nozzle and the ground and serves as a Faraday cage (FC). All discharges going from the erupting gas-particle mixture, the jet, to the nozzle will be recorded by a datalogger. All the discharges measured during the first 5 ms of ejection were taken into the evaluation of the discharge behaviour. The raw signals of the experiments were evaluated by a processing code developed by Gaudin and Cimarelli (2019). Additionally, the jet behaviour was recorded by a high-speed camera: the gas-exit angle and the exit angle of the gas-particle mixture were determined. The background of the high-speed video was divided into a black side and a white side. The gas-exit angle and the exit angle gas-particle-mixture were determined as the mean of the deviation angle of a straight trajectory angle of both sides.
This data publication provides data from 42 experiments from 2018 and 2019 in the Fragmentation Lab at the Ludwig-Maximilians University Munich (Germany). The experiments were taken out to analyse the influence of the water content and the initial temperature of the pre-experimental sample on the produced electrification in rapid decompression, shock-tube experiments. All samples used in this study are 90-300 μm loose ash samples from the lower Laacher See unit.To carry out this study, we have built up on previous studies by Cimarelli et al. (2014) and Gaudin & Cimarelli (2019b, dataset to be found in Gaudin & Cimarelli, 2019a). A sample of loose ash gets placed in an autoclave. In our study, we have added water in some experiments. Also, a furnace was often used to heat the sample to up to 320 °C. After both water addition and heating, the autoclave gets pressurized using argon gas. Once a target pressure of 9 MPa is reached, the experiment gets triggered by rupturing metal diaphragms, which rapid decompresses the sample and ejects it into a collector tank. This collector tank is made out of steel and electrically insulated from its surrounding, thus working as a Faraday cage (FC), which is able to detect the net charge within at any point during the experiment. We detect discharges on that net charge up to 10 ms after the ejection of the particles.This dataset contains:- an overview .xlsx file (ExperimentOverview) containing key information for the 42 experiments used for analysis in this study- raw .csv files for all experiments- .pdf files showing the key elements of the analysed experiments, incl. data from Faraday cage and pressure sensorsFor more information please refer to the data description and the associated publication (Stern et al., 2019).
Series of experiments to assess the role of pressure, mass of particles, and grain size distribution in the generation of charges and discharges during shock-tube experiments. Experiments have been achieved between 2017 and 2018 in the facilities of Department of Earth and Environmental Sciences - LMU München.This dataset contains:- an excel spreadsheet summarizing the 63 experiments in the database with their main characteristics- a pdf file for each experiment, with the waveforms of the main instruments used in the experiment (Pressure sensors and Faraday cage) as well as ellaborated data (total amount of charges and discharges, discharge size distribution.
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