“…Thermohydraulic explosion represents the most violent phreatomagmatic activity, that is, the phreatomagmatic explosion [Zimanowski, 1998]. In the context of fragmentation of solid material [e.g., Petrenko and Gluschenkov, 1996;Yoshida et al, 1997Yoshida et al, , 1998], impact events [e.g., Crawford and Schultz, 1988; Adushkin and Soloviev, 2819 1996], and nuclear explosion [e.g., Zablocki, 1966], very high electric charges were detected on a short timescale, and in some cases a proportionality of signal strength and intensity of the respective process was reported. The potency of brittle-type fragmentation of molten volcanic rock to generate significant electrical signals on a short timescale in laboratory experiments was reported by Biittner et al [1997].…”