Group by:  
Jump to:
Records: 2773
Koulakov Ivan, Gordeev Evgeniy I., Dobretsov Nikolay L., Vernikovsky Valery A., Senyukov Sergey, Jakovlev Andrey, Jaxybulatov Kayrly Rapid changes in magma storage beneath the Klyuchevskoy group of volcanoes inferred from time-dependent seismic tomography // Journal of Volcanology and Geothermal Research. 2013. Vol. 263. P. 75 - 91. doi: 10.1016/j.jvolgeores.2012.10.014.
We present the results of time-dependent local earthquake tomography for the Kluchevskoy group of volcanoes in Kamchatka, Russia. We consider the time period from 1999 to 2009, which covers several stages of activity of Kluchevskoy and Bezymianny volcanoes. The results are supported by synthetic tests that recover a common 3D model based on data corresponding to different time windows. Throughout the period, we observe a robust feature below 25 km depth with anomalously high Vp/Vs values (up to 2.2). We interpret this feature as a channel bringing deep mantle materials with high fluid and melt content to the bottom of the crust. This mantle channel directly or indirectly determines the activity of all volcanoes of the Kluchevskoy group. In the crust, we model complex structure that varies over time. During the pre-eruptive period, we detected two levels of potential magma storage: one in the middle crust at 10–12 km depth and one close to the surface just below Kluchevskoy volcano. In 2005, a year of powerful eruptions of Kluchevskoy and Besymiyanny volcanoes, we observe a general increase in Vp/Vs throughout the crust. In the relaxation period following the eruption, the Vp/Vs values are generally low, and no strong anomalous zones in the crust are observed. We propose that very rapid variations in Vp/Vs are most likely due to abrupt changes in the stress and deformation states, which cause fracturing and the active transport of fluids. These fluids drive more fracturing in a positive feedback system that ultimately leads to eruption. We envision the magma reservoirs beneath the Kluchevskoy group as sponge-structured volumes that may quickly change the content of the molten phases as fluids pulse rapidly through the system.
Ponomareva Vera, Portnyagin Maxim, Derkachev Alexander, Juschus Olaf, Garbe-Schönberg Dieter, Nürnberg Dirk Identification of a widespread Kamchatkan tephra: A middle Pleistocene tie-point between Arctic and Pacific paleoclimatic records // Geophysical Research Letters. 2013. Vol. 40. № 14. P. 3538-3543. doi:10.1002/grl.50645.
Very few age controls exist for Quaternary deposits over the vast territory of the East Russian Arctic, which hampers dating of major environmental changes in this area and prevents their correlation to climatic changes in the Arctic and Pacific marine domains. We report a newly identified ~177 ka old Rauchua tephra, which has been dispersed over an area of >1,500,000 km2 and directly links terrestrial paleoenvironmental archives from Arctic Siberia with marine cores in the northwest Pacific, thus permitting their synchronization and dating. The Rauchua tephra can help to identify deposits formed in terrestrial and marine environments during the oxygen isotope stage 6.5 warming event. Chemical composition of volcanic glass from the Rauchua tephra points to its island-arc origin, while its spatial distribution singles out the Kamchatka volcanic arc as a source. The Rauchua tephra represents a previously unknown, large (magnitude >6.5) explosive eruption from the Kamchatka volcanic arc.
Ponomareva Vera, Portnyagin Maxim, Derkachev Alexander, Pendea I. Florin, Bourgeois Joanne, Reimer Paula J., Garbe-Schönberg Dieter, Krasheninnikov Stepan, Nürnberg Dirk Early Holocene M~6 explosive eruption from Plosky volcanic massif (Kamchatka) and its tephra as a link between terrestrial and marine paleoenvironmental records // International Journal of Earth Sciences. 2013. Vol. 102. № 6. P. 1673-1699. doi:10.1007/s00531-013-0898-0.
We report tephrochronological and geochemical data on early Holocene activity from Plosky volcanic massif in the Kliuchevskoi volcanic group, Kamchatka Peninsula. Explosive activity of this volcano lasted for ~1.5 kyr, produced a series of widely dispersed tephra layers, and was followed by profuse low-viscosity lava flows. This eruptive episode started a major reorganization of the volcanic structures in the western part of the Kliuchevskoi volcanic group. An explosive eruption from Plosky (M~6), previously unstudied, produced tephra (coded PL2) of a volume of 10–12 km3 (11–13 Gt), being one of the largest Holocene explosive eruptions in Kamchatka. Characteristic diagnostic features of the PL2 tephra are predominantly vitric sponge-shaped fragments with rare phenocrysts and microlites of plagioclase, olivine and pyroxenes, medium- to high-K basaltic andesitic bulk composition, high-K, high-Al and high-P trachyandesitic glass composition with SiO2 = 57.5–59.5 wt%, K2O = 2.3–2.7 wt%, Al2O3 = 15.8–16.5 wt%, and P2O5 = 0.5–0.7 wt%. Other diagnostic features include a typical subduction-related pattern of incompatible elements, high concentrations of all REE (>10× mantle values), moderate enrichment in LREE (La/Yb ~ 5.3), and non-fractionated mantle-like pattern of LILE. Geochemical fingerprinting of the PL2 tephra with the help of EMP and LA-ICP-MS analyses allowed us to map its occurrence in terrestrial sections across Kamchatka and to identify this layer in Bering Sea sediment cores at a distance of >600 km from the source. New high-precision 14C dates suggest that the PL2 eruption occurred ~10,200 cal BP, which makes it a valuable isochrone for early Holocene climate fluctuations and permits direct links between terrestrial and marine paleoenvironmental records. The terrestrial and marine 14C dates related to the PL2 tephra have allowed us to estimate an early Holocene reservoir age for the western Bering Sea at 1,410 ± 64 14C years. Another important tephra from the early Holocene eruptive episode of Plosky volcano, coded PL1, was dated at 11,650 cal BP. This marker is the oldest geochemically characterized and dated tephra marker layer in Kamchatka to date and is an important local marker for the Younger Dryas—early Holocene transition. One more tephra from Plosky, coded PL3, can be used as a marker northeast of the source at a distance of ~110 km.
Romanova Iraida M. IVS FEB RAS Geoportal for integration and increasing availability of volcanological data // IAVCEI 2013 Scientific Assembly. July 20 - 24, Kagoshima, Japan. 2013. P. 1279
Romanova Iraida M., Girina O.A., Maximov Alexander P., Melekestsev Ivan V. Volcanoes of Kurile-Kamchatka Islands Arc information system // IAVCEI 2013 Scientific Assembly. July 20 - 24, Kagoshima, Japan. 2013. P. 1278
Shcherbakov Vasily D., Neill Owen K., Izbekov Pavel E., Plechov Pavel Yu. Phase equilibria constraints on pre-eruptive magma storage conditions for the 1956 eruption of Bezymianny Volcano, Kamchatka, Russia // Journal of Volcanology and Geothermal Research. 2013. Vol. 263. P. 132-140. doi:10.1016/j.jvolgeores.2013.02.010.
Taran Yuri, Inguaggiato Salvatore, Cardellini Carlo, Karpov Gennady Posteruption chemical evolution of a volcanic caldera lake: Karymsky Lake, Kamchatka // Geophysical Research Letters. 2013. Vol. 40. № 19. P. 5142-5146. doi:10.1002/grl.50961.
The 1996 short-lived subaqueous eruption at the Karymsky caldera lake suddenly changed the composition of the lake water. The lake, with a surface area of ∼10 km^2 and a volume of ∼0.5 km^3, became acidic, increased its salinity to ∼1000 mg/kg, and became dominated by SO4^2- and Ca^2+. Since the eruption, the lake chemistry has evolved in a predictable manner described by simple box model. As a result of dilution by incoming SO4-Ca-Mg-poor water, SO4, Ca, and Mg concentrations follow a simple exponential decrease with a characteristic time close to the residence time of the lake. Na, K, and Cl decrease relatively significantly slower, indicating a continuing input of these constituents into the lake that was initiated during the eruption. Thus, the dynamics of two groups of lake water solutes can be predicted by a simple box model for water and solute mass balance. Key Points Karymsky lake suddenly changed chemistry as a result of the 1996 eruption One-box dynamic model correctly describes the evolution of the lake chemistry The calculated fluxes of chemicals are in a good agreement with the field data
Volynets A.O., Melnikov D.V., Yakushev A.I. First data on composition of the volcanic rocks of the IVS 50th anniversary Fissure Tolbachik eruption (Kamchatka) // Doklady Earth Sciences. 2013. Vol. 452. № 1. P. 953-957. doi:10.1134/S1028334X13090201.
First data on major, minor and trace element (XRF. ICP-MS) concentrations in the volcanic rocks of the IVS 50th anniversary Fissure Tolbachik eruption are reported for the period from 27.11.2012 to 25.01.2013; scheme of lava flows distribution by March 2013 is made. The volcanic rocks of the new eruption are substantially different from the other studied volcanic rocks of Tolbachinsky Dol by their higher alkalis and incompatible elements content. The rocks of the first three days of eruption (Menyailov Vent) have higher silica and alkalis content than all previously reported volcanic rocks of Tolbachinsky Dol. Volcanic rocks of the Naboko Vent, at silica content similar to high-Al basalts of Tolbachinsky Dol, have different concentrations of trace elements and some major elements (K2O, CaO, TiO2, P2O5). REE and other incompatible element concentrations in the rocks of the Menyailov Vent are higher than in the rocks of the Naboko Vent at the same element ratios. The differences of the volcanic rocks of the two vents of the new eruption may be caused by the fact that the erupted lavas came from the different levels of the same magma chamber.
Volynets Anna, Melnikov Dmitry, Yakushev Anton, Tolstykh Maria Petrology and geochemistry of the New Tolbachik Fissure Eruption volcanic rocks and their evolution during the first two weeks of eruption // IAVCEI 2013 Scientific Assembly. July 20 - 24, Kagoshima, Japan. 2013. P. 743
West Michael E. Recent eruptions at Bezymianny volcano — a seismological comparison // Journal of Volcanology and Geothermal Research. 2013. Vol. 263. P. 42 - 57. doi: 10.1016/j.jvolgeores.2012.12.015.
Abstract For the past few decades, Bezymianny volcano has erupted once to twice per year. Here, I examine eight eruptive events between 2006 and 2010. This is the first time period for which proximal or broadband seismic data have been recorded at Bezymianny. Several recurring patterns are demonstrated in advance of eruptions. Eruptions are generally preceded by 12–36 h of tremor energy elevated by 2 to 3 orders of magnitude. Locatable earthquake activity is quite erratic in the days before eruptions. For eruptions of juvenile magma, however, the cumulative moment magnitude increases with the repose time since the previous eruption. Though tenuous, this relationship is statistically significant and could improve forecasts of Bezymianny eruptions. The most energetic eruptions demonstrate increasing multiplet activity in the run-up, followed by a rapid cessation at the time of eruption. When present, this behavior marks increasing pressure in the conduit system as degassing eclipses the capacity for venting. Very long period seismicity (> 20 s periods) accompanies some eruptions. These tend to be the same short-lived high-energy eruptions that exhibit multiplet precursors. Four eruptions are examined in detail to illustrate the variety in eruption mechanisms. Lava dome collapses, sustained eruptions, singular paroxysmal explosions and post-explosion lava flows occur in different combinations demonstrating that more than one eruption trigger is regulating Bezymianny. Compared to Bezymianny's fifty-year modern history, recent eruptions have been shorter-lived and separated by longer repose times. Some evidence suggests that these eruptions may be increasingly explosive—a speculation that carries significant hazard implications. If true, however, this threat is tempered by solid evidence that the most explosive eruptions are preceded by the clearest precursors, suggesting an ability to improve the already excellent eruption forecasts available for Bezymianny.