Abstract. According to World Wide Lightning Location Network (WWLLN) data, a sequence of lightning discharges was detected which occurred in the area of the explosive eruption of Shiveluch volcano on 16 November 2014 in Kamchatka. Information on the ash cloud motion was confirmed by the measurements of atmospheric electricity, satellite observations and meteorological and seismic data. It was concluded that WWLLN resolution is enough to detect the earlier stage of volcanic explosive eruption when electrification processes develop the most intensively. The lightning method has the undeniable advantage for the fast remote sensing of volcanic electric activity anywhere in the world. There is a good opportunity for the development of WWLLN technology to observe explosive volcanic eruptions.

Резюме Rus PDFInfrasound signals (IS), accompanied the most powerful episodes of the Raykoke volcano of the 21-22 June 2019, were registered by the network of observation stations, located at the distances of 335 to 974 km from the volcano. We identified IS of two frequency ranges: f = 0.08-0.5 Hz and f = 0.004-0.012 Hz. The first one was caused by magma fragmentation and nonstationary processes, appeared during the ash-gas mix outflowing from the crater. The second IS range is associated with an eruptive column forming and an eruptive cloud appearance. In this case the separate eruption episodes are considered as a continuous heat source. On the base of kinematic and dynamic parameters of IS of the first range, we carried out the detailed reconstruction of the eruption course, there 11 separate episodes (explosions) were distinguished. Wave pattern of IS allowed to defined four episodes (no. 1, 5, 6, 8) as explosions, in other cases a high-speed outflow of ash-gas mix ("blow") occurred from the volcano vent. The most long "blow" (no. 9) lasted for ~3.5 hr. On the base of IS of the second range, we estimated the minimal volume of the ash ejected into the atmosphere (by the methodology of Yu.A. Gostintsev and Yu.A. Shatskih) as >0.1 km 3 , that allows us to assign the index of explosive activity VEI -4 for this eruption.

The number of explosive eruptions at Shiveluch Volcano has significantly increased over the past years, which requires close volcanic monitoring using all available techniques. In order to implement a new monitoring technique into integrated methods of volcano monitoring, the authors analyze response to the intensity of the vertical component in the atmospheric electrical field (EZ AEF) during the movement of ash clouds. Two eruptions of different intensity that occurred December 16, 2016 and June 14, 2017 at Shiveluch were selected for study. We used a combination of satellite, seismic, and infrasound data to select signals in the EZ AEF field. Signals with negative polarity that accompanied ashfalls in the EZ AEF dynamics were registered for both eruptions within the closest area (< 50 km). In the former case, the ash cloud was “dry” and thus it caused aerial-electrical structure of the negatively charged cloud. In the latter case, a strong explosion sent into the atmosphere the large volume of ash and volcanic gases (98% in form of vapour) that resulted in the formation of a dipolar aerial-electrical structure caused by eolian differentiation within the closest area. At the distance of more than 100 km we registered a positive-going signal that is attributive to the aerial-electrical structure of the positively charged type of the cloud.

No abstract

The number of explosive eruptions at Shiveluch Volcano has significantly increased over the past years, which requires close volcanic monitoring using all available techniques. In order to implement a new monitoring technique into integrated methods of volcano monitoring, the authors analyze response to the intensity of the vertical component in the atmospheric electrical field (EZ AEF) during the movement of ash clouds. Two eruptions of different intensity that occurred December 16, 2016 and June 14, 2017 at Shiveluch were selected for study. We used a combination of satellite, seismic, and infrasound data to select signals in the EZ AEF field. Signals with negative polarity that accompanied ashfalls in the EZ AEF dynamics were registered for both eruptions within the closest area (< 50 km). In the former case, the ash cloud was “dry” and thus it caused aerial-electrical structure of the negatively charged cloud. In the latter case, a strong explosion sent into the atmosphere the large volume of ash and volcanic gases (98% in form of vapour) that resulted in the formation of a dipolar aerial-electrical structure caused by eolian differentiation within the closest area. At the distance of more than 100 km we registered a positive-going signal that is attributive to the aerial-electrical structure of the positively charged type of the cloud.