Girina O.A. On Precursor of Kamchatkan Volcanoes Eruptions Based on Data from Satellite Monitoring // Journal of Volcanology and Seismology. 2012. V. 6. № 3. P. 142-149. doi: 10.1134/S0742046312030049.
Kamchatka is one of the most active volcanic regions on the planet. Large explosive volcanic eruptions, in which the ash elevates up to 8–15 km above sea level, occur here every 1.5 years. Study of eruptions precursors in order to reduce a volcanic risk for the population is an urgent problem of Volcanology. The available precursor of strong explosive eruptions of volcanoes, identified from satellite data (thermal anomaly), as well as examples of successful prediction of eruptions using this precursor, are represented in this paper.
Hoff U., Dirksen O., Dirksen V., Herzschuh U., Hubberten H.-W., Meyer H., van den Bogaard C., Diekmann B. Late Holocene diatom assemblages in a lake-sediment core from Central Kamchatka, Russia // Journal of Paleolimnology. 2012. V. 47. V. 4. P. 549-560. doi: 10.1007/s10933-012-9580-y.
Fossil diatom assemblages in a sediment core from a small lake in Central Kamchatka (Russia) were used to reconstruct palaeoenvironmental conditions of the late Holocene. The waterbody may be a kettle lake that formed on a moraine of the Two-Yurts Lake Valley, located on the eastern slope of the Central Kamchatka Mountain Chain. At present, it is a seepage lake with no surficial outflow. Fossil diatom assemblages show an almost constant ratio between planktonic and periphytic forms throughout the record. Downcore variations in the relative abundances of diatom species enabled division of the core into four diatom assemblage zones, mainly related to changes in abundances of Aulacoseira subarctica, Stephanodiscus minutulus, and Discostella pseudostelligera and several benthic species. Associated variations in the composition and content of organic matter are consistent with the diatom stratigraphy. The oldest recovered sediments date to about 3220 BC. They lie below a sedimentation hiatus and likely include reworked deposits from nearby Two-Yurts Lake. The initial lake stage between 870 and 400 BC was characterized by acidic shallow-water conditions. Between 400 BC and AD 1400, lacustrine conditions were established, with highest contributions from planktonic diatoms. The interval between AD 1400 and 1900 might reflect summer cooling during the Little Ice Age, indicated by diatoms that prefer strong turbulence, nutrient recycling and cooler summer conditions. The timing of palaeolimnological changes generally fits the pattern of neoglacial cooling during the late Holocene on Kamchatka and in the neighbouring Sea of Okhotsk, mainly driven by the prevailing modes of regional atmospheric circulation.
Kopylova G.N., Boldina S.V. On the Relationships of Water-Level Variations in the E-1 Well, Kamchatka to the 2008–2009 Resumption of Activity on Koryakskii Volcano and to Large (M ≥ 5) Earthquakes // Journal of Volcanology and Seismology. 2012. V. 6. № 5. P. 312-328. doi: 10.1134/S074204631205003X.
Abstract—We discuss the water!level variations in the E!1 well for the time period between May 2006 and
2010, inclusive. A trend towards an increasing level at an abnormally high rate occurred from mid!2006 to
December 2009. This increase is regarded as the response of the aquifer of gas!saturated ground water that
exists in the volcanogenic–sedimentary deposits of the Avacha volcano!tectonic depression to volumetric
strain changes during the precursory period and the occurrence of a swarm of small earthquakes ( = 8.3)
in the area of Koryakskii Volcano and to its phreatic eruption. We estimated the volumetric compression as
Δε = –(4.1 × 10–6–1.5 × 10–5) from the amplitude of water!level rise using the elastic parameters of the wa!
ter!saturated rocks. While the strain source was active, we observed a decreasing sensitivity of the hydrologic
regime in the well to the precursory processes before large (M ≥ 5.0) tectonic earthquakes.
Ladygin V.М., Girina O.A., Frolova Yu.V. Petrophysical features of lava flows from Bezymyannyi volcano, Kamchatka // Journal of Volcanology and Seismology. 2012. V. 6. № 6. P. 341-351. doi: 10.1134/S074204631206005X.
This paper presents results from a study of lava flows that were discharged by Bezymyannyi Volcano at different times, from old (about 3500 years ago) to recent ones (1985–1989). We provide detailed descriptions of the composition, structure, and petrophysical properties for the main types of constituent rocks, which are andesites and basaltic andesites. It was found that porosity is the leading factor that controls rock properties, while the effects of structural and mineralogical features are less prominent. We demonstrate the variation in the properties of rocks that compose the lava flows in relation to their ages: the older a rock is, the higher its density and strength and the lower its porosity is.
Ponomareva Vera A chronology of the Holocene eruptions from the northern Kamchatka volcanoes based on linking major C14-dated tephra sequences with the help of EMPA glass data // Quaternary International. 2012. V. 279–28. P. 383 doi: 10.1016/j.quaint.2012.08.1191.
Volcanic eruptions from Kamchatka have deposited many unique tephra layers over a large region within the North Pacific, providing important isochrons between key sites such as marine ODP core 883 (Pacific Ocean, Detroit Seamount) and Elgygytgyn Lake (Chukotka, eastern Siberia). Here we present a compilation of C14 dates on major Holocene tephras from the volcanically highly active region, based on decades of detailed stratigraphical fieldwork on Shiveluch, Kliuchevskoy, and other volcanoes.The 12-m thick tephra sequence at the Kliuchevskoy slope has been continuously accumulating during the last ∼11 ka. It contains over 200 visible individual tephra layers and no datable organic material. The section is dominated by dark-gray mafic cinders related to Kliuchevskoy activity. In addition, it contains 30 light-colored thin layers of silicic tephra from distant volcanoes including 11 layers from Shiveluch volcano located only 65 km to the north. We have used EMPA glass analysis to correlate most of the marker tephra layers to their source eruptions dated earlier by C14 (Braitseva et al., 1997; Ponomareva et al., 2007), and in this way linked Kliuchevskoy tephra sequence to sequences at other volcanoes including Shiveluch. The C14 dates and tephras from the northern Kamchatka are then combined into a single Bayesian framework taking into account stratigraphical ordering within and between the sites. This approach has allowed us to enhance the reliability and precision of the estimated ages for the eruptions. Age-depth models are constructed to analyse changes in deposition rates and volcanic activity throughout the Holocene. This detailed chronology of the eruptions serves as a basis for understanding temporal patterns in the eruption sequence and geochemical variations of magmas. This research could prove important for the long-term forecast of eruptions and volcanic hazards.
Tolstykh M.L., Naumov V.B., Gavrilenko M.G., Ozerov A.Yu., Kononkova N.N. Chemical composition, volatile components, and trace elements in the melts of the Gorely volcanic center, southern Kamchatka: Evidence from inclusions in minerals // Geochemistry International. 2012. V. 50. № 6. P. 522-550. doi:10.1134/S0016702912060079.
Viccaro Marco, Giuffrida Marisa, Nicotra Eugenio, Ozerov Alexey Yu. Magma storage, ascent and recharge history prior to the 1991 eruption at Avachinsky Volcano, Kamchatka, Russia: Inferences on the plumbing system geometry // Lithos. 2012. V. 140–14. P. 11 - 24. doi: 10.1016/j.lithos.2012.01.019.
Textural and compositional features of plagioclase phenocrysts of the 1991 eruption lavas at Avachinsky Volcano (Kamchatka, Russia) were used to investigate the feeding system processes. Volcanics are porphyritic basaltic andesites and andesites with low-K affinity. A fractionation modeling for both major and trace elements was performed to justify the development of these evolved compositions. The occurrence of other magma chamber processes was verified through high-contrast BSE images and core-to-rim compositional profiles (An and FeO wt.) on plagioclase crystals. Textural types include small and large-scale oscillation patterns, disequilibrium textures at the crystal core (patchy zoning, coarse sieve-textures, dissolved cores), disequilibrium textures at the crystal rim (sieve-textures), melt inclusion alignments at the rim. Disequilibrium textures at the cores may testify episodes of destabilization at various decompression rates under water-undersaturated conditions, which suggests different pathways of magma ascent at depth. At shallower, water-saturated conditions, plagioclase crystallization continues in a system not affected by important chemical-physical perturbations (oscillatory zoning develops). Strongly sieve-textured rims, along with An increase at rather constant FeO, are evidence of mixing before the 1991 eruption between a residing magma and a hotter and volatile-richer one. The textural evidence implies that crystals underwent common histories at shallow levels, supporting the existence of a large magma reservoir whose top is at ~ 5.5 km of depth. Distinct textures at the outer rims in a hand-size sample are evidence that crystals mix mechanically at very shallow levels, probably in a small reservoir at ~ 1.8 km of depth.
Vikulin A.V., Akmanova D.R., Vikulina S.A., Dolgaya A.A. Migration of seismic and volcanic activity as display of wave geodynamic process
// Geodynamics & Tectonophysics. 2012. V. 3. № 1. P. 1-18. doi: 10.5800/GT-2012-3-1-0058.
Publications about the earthquake foci migration have been reviewed. An important result of such studies is establishment of wave nature of seismic activity migration that is manifested by two types of rotational waves; such waves are responsible for interaction between earthquakes foci and propagate with different velocities. Waves determining long-range interaction of earthquake foci are classified as Type 1; their limiting velocities range from 1 to 10 cm/s. Waves determining short-range interaction of foreshocks and aftershocks of individual earthquakes are classified as Type 2; their velocities range from 1 to 10 km/s. According to the classification described in [Bykov, 2005], these two types of migration waves correspond to slow and fast tectonic waves.
The most complete data on earthquakes (for a period over 4.1 million of years) and volcanic eruptions (for 12 thousand years) of the planet are consolidated in a unified systematic format and analyzed by methods developed by the authors. For the Pacific margin, Alpine-Himalayan belt and the Mid-Atlantic Ridge, which are the three most active zones of the Earth, new patterns of spatial and temporal distribution of seismic and volcanic activity are revealed; they correspond to Type 1 of rotational waves. The wave nature of the migration of seismic and volcanic activity is confirmed. A new approach to solving problems of geodynamics is proposed with application of the data on migration of seismic and volcanic activity, which are consolidated in this study, in combination with data on velocities of movement of tectonic plate boundaries. This approach is based on the concept of integration of seismic, volcanic and tectonic processes that develop in the block geomedium and interact with each other through rotating waves with a symmetric stress tensor. The data obtained in this study give grounds to suggest that a geodynamic value, that is mechanically analogous to an impulse, remains constant in such interactions. It is thus shown that the process of wave migration of geodynamic activity should be described by models with strongly nonlinear equations of motion.
Проведен обзор работ по миграции очагов землетрясений. Важным результатом явилось установление волновой природы миграции сейсмической активности, которая осуществляется двумя типами ротационных волн, ответственными за взаимодействие очагов землетрясений и распространяющимися с разными скоростями. Первому типу с предельными скоростями 1–10 см/с соответствуют волны, определяющие дальнодействующее взаимодействие очагов землетрясений, второму – с предельными скоростями 1–10 км/с – соответствуют волны, определяющие близкодействующее взаимодействие форшоков и афтершоков в пределах отдельно взятых очагов землетрясений. Согласно классификации [Bykov, 2005], такие типы волн миграции соответствуют медленным и быстрым тектоническим волнам.
В едином формате представлены наиболее полные данные о землетрясениях за 4.1 тыс. лет и извержениях вулканов за 12 тыс. лет. Собранные данные систематизированы и проанализированы с помощью разработанных авторами методик. Для трех наиболее активных поясов Земли – Пацифики, Альпийско-Гималайского и Срединно-Атлантического – установлены новые, отвечающие первому типу ротационных волн, закономерности пространственно-временного распределения сейсмической и вулканической активности. Подтверждена волновая природа их миграции. Полученные в работе данные в совокупности с данными о скоростях движения границ тектонических плит предлагается использовать в качестве нового подхода к решению задач геодинамики. В основе такого подхода заложена идея единства сейсмического, вулканического и тектонического процессов, протекающих в блоковой геосреде и взаимодействующих между собой посредством ротационных волн с симметричным тензором напряжений. Полученные авторами данные позволяют предположить, что при таком взаимодействии сохраняется геодинамическая величина, механическим аналогом которой является импульс. Показано, что процесс волновой миграции геодинамической активности должен описываться в рамках моделей с сильно нелинейными уравнениями движения.