Дано описание извержений двух гигантских вулканов Камчатки, которые произошли в 1993 г. Наблюдались пирокластические потоки, лахары, пеплопады и взаимодействие лавовых и пирокластических потоков с ледниками. Приведены данные о росте андезитового купола и объеме выброшенного пепла вулкана Шивелуч, а также объеме излившейся андезитобазальтовой магмы Ключевского вулкана. Изучены последствия обоих извержений. Показано, что Шивелуч и Ключевской различаются по типу извержений и составу вулканических продуктов и поэтому оказывают разное влияние на окружающую среду. Отмечены существенные отличия в характере вулканической опасности.

Records of microbarographic instruments in the near zone (45 and 113 km) were used for a detailed analysis of wave disturbances in the atmosphere accompanying the November 12, 1964 Shiveluch eruption. It is shown that the wave disturbances due to this major explosive eruption were largely caused by the formation of a convective column; they provide information on the time history of the eruption and the amount of erupted ash. The relation between seismic and acoustic intensities shows that the eruption started with a giant landslide (1.5 km3) giving rise to an ash cloud that produced the first acoustic signal. Volcanic tremor began 12 min after the slide and a second acoustic source began operating. This was related to starting Plinian activity and eruption of pyroclastic flows. The transition from one phase of the eruption to the next was accompanied by increased volcanic tremor and acoustic signal component of frequency > 0.05 Hz, as well as by generation of a long period (greater than 10 min) disturbance having an excess pressure of 50 Pa at 113 km distance. The amount of ash ejected into the atmosphere as inferred from long period disturbance energy is estimated to be 0.35-0.45 km3, which is in satisfactory agreement with geological evidence (0.3 km3).

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 positivegoing signal that is attributive to the aerial-electrical structure of the positively charged type of the cloud.