New and published data on the composition of melt inclusions in olivine (Fo73_yi) from volcanoes of the Kamchatka and northern Kurile Arc are used 1) to evaluate the combined systematics of volatiles (H2O, S, Cl, F) and incompatible trace elements in their parental magmas and mantle sources, 2) to constrain thermal conditions of mantle melting, and 3) to estimate the composition of slab-derived components. We demonstrate that typical Kamchatkan arc-type magmas originate through 5-14% melting of sources similar or slightly more depleted in HFSE (with up to -1 wt.% previous melt extraction) compared to MORB-source mantle, but strongly enriched in H2O,B, Be, Li, Cl. F, LILE, LREE, Th and U. Mean H2O in parental melts f 1.8-2.6 wt.%) decreases with increasing depth to the subducting slab and correlates negatively with both 'fluid-immobile* (e.g. Ti, Na, LREE) and most 'fluid-mobile' (e.g. LILE, S, Cl, F) incompatible elements, implying that solubility in hydrous fluids or amount of water does not directly control the abundance of 'fluid-mobile' incompatible elements. Strong correlation is observed between H2O/Ce and B/Zr (or B/LREE) ratios. Both, calculated H2O in mantle sources (0.1-0.4%) and degrees of melting (5-14%) decrease with increasing depth to the slab indicating that the ultimate source of water in the sub-arc mantle is the subducting oceanic plate and that water flux (together with mantle temperature) governs theextent of mantle melting beneath Kamchatka. A parameterized hydrous melting model [Katzetal. 2003, G3,4(9), 1073] is utilized to estimate that mantle melting beneath Kamchatka occurs at or below the dry peridotite solidus (1245-1330 °C at 1.5-2.0 GPa). Relatively high mantle temperatures (yet lower than beneath back-arc basins and ocean ridges) suggest substantial corner flow driven mantle upwelling beneath Kamchatka in agreement with numerical models implying non-isoviscous mantle wedge rheology. Data from Kamchatka, Mexico and Central America indicate that <5% melting would lake place beneath continental arcs without water flux from the subducting slab. A broad negative correlation appears to exist between crustal thickness and the temperature of magma generation beneath volcanic arcs with larger amounts of decompression melting occurring beneath thinner arc crust (Uihosphere). In agreement with the high mantle temperatures, we observe a systematic change in the composition of slab components with increasing slab depth from solute-poor hydrous fluid beneath the volcanic front to solute-rich hydrous melt or supercritical liquid at deeper depths beneath the rear arc. The solute-rich slab component dominates the budget of LILE, LREE,Th and U in the magmas and originates through wet-melting of subducted sediments and/or altered oceanic crust at > 120 km depth. Melting of the upper parts of subducting plates under water flux from deeper luhosphere (e.g. serpentinites), combined with high .emperatures in the mantie wedge, may be a more common process beneath volcanic arcs than has been previously recognized. 0 2006 Klsevier B.V. All rights reserved.

Numerous ash layers deposited at the slopes of Kliuchevskoi volcano provide a detailed and continuous record of its explosive activity during the last ca. 10,000 years.

Since its launch in December 1999, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument has been observing over 1300 of the world's volcanoes during the day and night and at different times of the year. At the onset of an eruption, the temporal frequency of these regularly scheduled observations can be increased to as little as 1–3 days at higher latitudes. However, even this repeat time is not sufficient for near real-time monitoring, which is on the order of minutes to hours using poorer spatial resolution (>1 km/pixel) instruments. The eruption of Bezymianny Volcano (Kamchatkan Peninsula, Russia) in March 2000 was detected by the Alaska Volcano Observatory (AVO) and also initiated an increased observation frequency for ASTER. A complete framework of the eruptive cycle from April 2000 to January 2001 was established, with the Advanced Very High Resolution Radiometer (AVHRR) data used to monitor the large eruptions and produce the average yearly background state for the volcano. Twenty, nearly cloud-free ASTER scenes (2 days and 18 nights) show large thermal anomalies covering tens to hundreds of pixels and reveal both the actively erupting and restive (background) state of the volcano. ASTER short-wave infrared (SWIR) and thermal infrared (TIR) data were also used to validate the recovered kinetic temperatures from the larger AVHRR pixels, as well as map the volcanic products and monitor the thermal features on the summit dome and surrounding small pyroclastic flows. These anomalies increase to greater than 90 °C prior to a larger eruption sequence in October 2000. In addition, ASTER has the first multispectral spaceborne TIR capability, which allowed for the modeling of micrometer-scale surface roughness (vesicularity) on the active lava dome. Where coupled with ongoing operational monitoring programs like those at AVO, ASTER data become extremely useful in discrimination of small surface targets in addition to providing enhanced volcanic mapping capabilities.

Abstract We test two methods of 3-D acoustic source localization on volcanic explosions and small-scale jetting events at Karymsky Volcano, Kamchatka, Russia. Recent infrasound studies have provided evidence that volcanic jets produce low-frequency aerodynamic sound (jet noise) similar to that from man-made jet engines. For man-made jet noise, noise sources localize along the turbulent jet flow downstream of the nozzle. Discrimination of jet noise sources along the axis of a volcanic jet requires high resolution in the vertical dimension, which is very difficult to achieve with typical volcano-acoustic network geometries. At Karymsky Volcano, an eroded edifice (Dvor Caldera) adjacent to the active cone provided a platform for the deployment of five infrasound sensors in July 2012 with intra-network relief of ~ 600 m. The network was designed to target large-scale jetting, but unfortunately only small-scale jetting and explosions were recorded during the 12-day experiment. A novel 3-D inverse localization method, srcLoc, is tested and compared against a more common grid-search semblance technique. Simulations using synthetic signals show that srcLoc is capable of determining vertical solutions to within ± 150 m or better (for signal-to-noise ratios ≥ 1) for this network configuration. However, srcLoc locations for explosions and small-scale jetting at Karymsky Volcano show a persistent overestimation of source elevation and underestimation of sound speed. The semblance method provides more realistic source locations, likely because it uses a fixed, realistic sound speed of ~ 340 m/s. Explosion waveforms exhibit amplitude relationships and waveform distortion strikingly similar to those theorized by modeling studies of wave diffraction around the crater rim. We suggest that the delay of acoustic signals and apparent elevated source locations are due to raypaths altered by topography and/or crater diffraction effects, implying that topography in the vent region must be accounted for when attempting 3-D volcano acoustic source localization. Though the data presented here are insufficient to resolve small-scale jet noise sources, similar techniques may be successfully applied to large volcanic jets in the future.

Abstract The active basaltic volcano Plosky Tolbachik (Pl. Tolbachik) is located in the southern part of the Klyuchevskoy volcano group on the Kamchatka Peninsula. The previous 1975–1976 Great Tolbachik Fissure Eruption (1975–1976 GTFE) occurred in the southern sector of Pl. Tolbachik. It was preceded by powerful earthquakes with local magnitudes between 2.5 and 4.9 and it was successfully predicted with a short-term forecast. The Kamchatka Branch of Geophysical Survey (KBGS) of the Russian Academy of Science (RAS) began to publish the results of daily seismic monitoring of active Kamchatka volcanoes on the Internet in 2000. Unlike the 1975–1976 {GTFE} precursor, (1) seismicity before the 2012–2013 Tolbachik Fissure Eruption (2012–2013 TFE) was relatively weak and earthquake magnitudes did not exceed 2.5. (2) Precursory earthquake hypocenters at 0–5 km depth were concentrated mainly under the southeastern part of the volcano. (3) The frequency of events gradually increased in September 2012, and rose sharply on the eve of the eruption. (4) According to seismic data, the explosive-effusive 2012–2013 {TFE} began at ~ 05 h 15 min {UTC} on November 27, 2012; the outbreak occurred between the summit of the Pl. Tolbachik and the Northern Breakthrough of the 1975–1976 GTFE. (5) Because of bad weather, early interpretations of the onset time and the character of the eruption were made using seismological data only and were confirmed later by other monitoring methods. The eruption finished in early September 2013. This article presents the data obtained through real-time seismic monitoring and the results of retrospective analysis, with additional comments on the future monitoring of volcanic activity.

This paper considers the propagation of ash during the paroxysmal eruption of Sheveluch Volcano which occurred April 10–13, 2023, and its impact on the water resources of the affected area. We characterize ash thicknesses at various population centers and describe the grain-size composition of the ash. We show that the propagation of ash plumes is primarily driven by the eruption dynamics, but atmospheric circulation actually controls the spatial distribution of deposit thickness. The water-soluble salts contained in the ash and the dynamics of their washing out under natural conditions have been determined. The water-soluble part of fresh ash is dominated by calcium and magnesium sulfates, sodium chloride, with minor amounts of chlorides and fluorides of aluminum, potassium, and ammonium. The first substances to be washed out from ashes are well-soluble chlorides, to be followed by sulfates. As time goes on, the total concentration of soluble salts is decreasing, and their qualitative composition changes: hydrogen carbonates of calcium, magnesium, and sodium begin to dominate. Several months after the eruption, the impact of the ashfall on water resources of the settlements, including open springs at the ground surface, was leveled out.