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 paper provides an overview of recent studies related to the shock-wave and acoustic effects in the atmosphere from volcanic eruptions. Brief description is given to the development of a new trend known as Acoustics from Volcanic Eruptions (AVE) and informational content of wave disturbances in the atmosphere regarding the dynamics of eruptions and parameters of explosive process. Wave disturbances in the atmosphere from volcanic eruptions were classified and presented in the paper to explain their unique nature.

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.

The paper presents the results of integrated geophysical observations of the Ebeko Volcano’s activity in late 2018 and early 2019. The instrument complex for observation was located at the Severo-Kurilsk seismic station at a distance of 7.2 km far from the volcanic crater. Three types of response in the vertical component of the electric field of the atmosphere have been distinguished during the drift of eruptive clouds from the Ebeko Volcano’s explosions, which gives evidence for various mechanisms of their occurrence. The registration of infrasonic acoustic signals in the near zone made it possible to estimate the trinitrotoluene equivalent for the strongest explosions, which was calculated to be about 100 kg of trinitrotoluene. The authors have revealed certain regularities in the dynamics of the volumetric activity of radon, associated with variations in meteorological values and hydrological features of the registration point. A long period of its activity and the proximity of the observation point to the crater give reason to suggest Ebeko Volcano to be a natural laboratory for studying the mechanisms of eruptions.

Growth of explosive activity of Ebeko volcano in April–June 2020

On March 24, 2017 Kambalniy Volcano started to erupt after a 500-year-long period of rest. The eruption continued till April 10, 2017. The paper provides the analysis of atmospheric wave disturbances as wavetrains of quasi-sinusoidal oscillations with a frequency of 8 Hz ("acoustic tremor" or AT), which occurred at certain moments during the eruption. Besides, the paper describes 3 strongest seismic signals registered at the initial stages of the eruptions simultaneously with AT, which was registered using an infrasound station IS44 installed 208 km NW far from the volcano. The nearest "Pauzhetka" seismic station installed 19 far from the volcano allowed monitoring the seismic build-up, which was short (2 days) and weak (Кmax = 8.6). Lack of definite discrete infrasound signals, which are usually caused by non-stationary process during explosive eruptions, gives evidence for peculiar pattern of formation and effusion of ash-and-gas emissions. Such uncommon acoustic radiations and seismic build-up prove the presumption that this eruption should be classified as a hydrothermal event.

Приводятся сведения об особенностях поведения временного ряда объемной активности радона за период 2000–2015 гг. в зоне влагонасыщения в районе Паратунского геотермального месторождения и временного ряда объемной доли молекулярного водорода газа теплоносителя скв. 016 Мутновского месторождения и их связи с сейсмичностью северо-западного обрамления Тихого океана. Сделан вывод, что длительные тренды в динамике объемной активности радона и высокая объемная доля молекулярного водорода в 2014 г. обусловлены изменением поля напряжений в зоне субдукции северо-западного фланга Тихого океана. Сделано предположение о возможности землетрясения с М > 7.5 в ближайшее 1.5 года. По данным академика С.А. Федотова, наиболее вероятный район этого события – от полуострова Шипунский до острова Шиашкотан (Средние Курилы)

Рассмотрена динамика газового состава теплоносителя Мутновской Геотермальной электростанции за период июнь - декабрь 2004 г. Выявлена тенденция снижения доли газа и понижения в нем отношения CO2/H2S.