


Vol 10, No 6 (2016)
- Year: 2016
- Articles: 4
- URL: https://journal-vniispk.ru/0742-0463/issue/view/10885
Article
Estimating the predictability of the seismicity rate: The 1964 eruption of Shiveluch Volcano
Abstract
This paper describes a method for estimating the predictability of the seismicity rate for volcanic edifices. The mathematical model is a nonlinear second-order differential equation, with our own algorithms for optimization and for estimating predictability. The method is illustrated by the 1964 eruption on Shiveluch Volcano. Calculations showed that the seismicity rate can be predicted with success for a time interval ranging between a few days and a few tens of days during the active phase and between a few tens of days and a few hundreds of days during the decay phase. The level of predictability is rather high, with the prediction distance exceeding the mean error by two to four orders of magnitude. The nonlinear character of both the active phase of the process and of its decay phase is close to the law of an equilateral hyperbola. The method, as developed in this paper, allows a realistic approach to the prediction of that part of the volcanic process which involves brittle deformation and/or rapid displacements of material along the newly arisen cracks.



Dynamics of exrtrusive dome growth and variations in chemical and mineralogical composition of Young Shiveluch andesites in 2001–2013
Abstract
This paper discribes characteristic features of the extrusive dome growth of the Young Shiveluch Volcano in 2001–2013 and analyzes variations in the chemical and mineralogic composition of magmas erupted during this period. It is shown that, compared with the earlier phases in the dome growth during 1980–1981 and 1993–1995, the andesites that were erupted in the 2000s are less homogeneous in bulk composition, crystal contents and contain phenocrysts, which differ in composition and the conditions of crystallization. These compositional feature of rocks are interpreted as resulting from convection in a shallow magma chamber, with the convection being caused by the arrival of a fresh portion of deep magma.



The VolSatView information system for Monitoring the Volcanic Activity in Kamchatka and on the Kuril Islands
Abstract
Kamchatka and the Kuril Islands are home to 36 active volcanoes with yearly explosive eruptions that eject ash to heights of 8 to 15 km above sea level, posing hazards to jet planes. In order to reduce the risk of planes colliding with ash clouds in the north Pacific, the KVERT team affiliated with the Institute of Volcanology and Seismology of the Far East Branch of the Russian Academy of Sciences (IV&S FEB RAS) has conducted daily satellite-based monitoring of Kamchatka volcanoes since 2002. Specialists at the IV&S FEB RAS, Space Research Institute of the Russian Academy of Sciences (SRI RAS), the Computing Center of the Far East Branch of the Russian Academy of Sciences (CC FEB RAS), and the Far East Planeta Center of Space Hydrometeorology Research (FEPC SHR) have developed, introduced into practice, and were continuing to refine the VolSatView information system for Monitoring of Volcanic Activity in Kamchatka and on the Kuril Islands during the 2011–2015 period. This system enables integrated processing of various satellite data, as well as of weather and land-based information for continuous monitoring and investigation of volcanic activity in the Kuril–Kamchatka region. No other information system worldwide offers the abilities that the Vol-SatView has for studies of volcanoes. This paper shows the main abilities of the application of VolSatView for routine monitoring and retrospective analysis of volcanic activity in Kamchatka and on the Kuril Islands.



An analysis of geomagnetic response functions prior to the Tohoku, Japan earthquake
Abstract
Geomagnetic records from 20 Japanese observatories have been used to yield time series of response function (RF) components for 20 years at periods of between 2.5 and 60 min. Six observatories showed anomalous variations lasting 3–5 years in the short period part of the above range of periods prior to the March 11, 2011 Tohoku earthquake. The variations could have been intermediate-term precursors. We made a detailed analysis of how noise affects the results using coherence criteria, visual control, and the remote-reference technique. We clarified the conditions that make response functions dependent on geomagnetic activity. For 19 observatories we constructed the tensor of the anomalous magnetic field with Kakioka as the base site. An anomaly in electrical conductivity striking WNW–ESE has been identified beneath the Boso Peninsula near Tokyo in the conditions of strong noise. We sought to corroborate the reality of the anomaly by visual control and processing of nighttime records with minimum noise. We advanced idea that precursors can be monitored using the DC noise field in the presence of a shallow conductivity anomaly. We provided a tectonic interpretation of the obtained RF anomalies. The Boso conductivity anomaly is interpreted as being due to a graben-shaped structure of the sediments and possibly to a deeper plate-tectonics structure, that is, the Sagami Trough. We examine similarities and differences between the Boso anomaly and the Avacha anomaly in Kamchatka, and provided recommendations for further study of the Boso anomaly and for using the Avacha anomaly to monitor EM precursors in Kamchatka.


