Similar behaviour was observed across 10 experiments with the release of either liquid water or superheated water due to steam forming as a result of the depressurization27. However, as reported in Fazio et al.27, the signals generated at elevated temperatures had duration in the order of tens of milliseconds in both scenarios, almost 1000 times shorter than the events reported here (Fig. 3a). Previous studies14,20 found that a longer signal is expected when dusty gases are involved, followed by mixtures of ash and SO2 and finally using mixtures of H2O and water droplets. In addition, by looking at the quality factor (Q) of LP events induced by the different fluid mixtures20,21, it is shown that ash-gases mixture are responsible for the highest Q (followed by H2O and water droplets) while bubbly water accounts for the lowest Q. Therefore we assume that the duration of the signal increases with decreasing liquid water content, in agreement with the results of this study and Fazio et al.27. Finally, we note that as the Nitrogen flows through the fractured rock, it is likely that the finest comminuted material is incorporated in the flowing fluid, hence forming a dusty gas.