Ebeko Volcano Research Articles

Trace Elements and Minerals in Fumarolic Sulfur: The Case of Ebeko Volcano, Kuriles

Native sulfur deposits on fumarolic fields at Ebeko volcano (Northern Kuriles, Russia) are enriched in chalcophile elements (As-Sb-Se-Te-Hg-Cu) and contain rare heavy metal sulfides (Ag2S, HgS, and CuS), native metal alloys (Au2Pd), and some other low-solubility minerals (CaWO4, BaSO4). Sulfur incrustations are impregnated with numerous particles of fresh and altered andesite groundmass and phenocrysts (pyroxene, magnetite) as well as secondary minerals, such as opal, alunite, and abundant octahedral pyrite crystals. The comparison of elemental abundances in sulfur and unaltered rocks (andesite) demonstrated that rock-forming elements (Ca, K, Fe, Mn, and Ti) and other lithophile and chalcophile elements are mainly transported by fumarolic gas as aerosol particles, whereas semimetals (As, Sb, Se, and Te), halogens (Br and I), and Hg are likely transported as volatile species, even at temperatures slightly above 100°C. The presence of rare sulfides (Ag2S, CuS, and HgS) together with abundant FeS2 in low-temperature fumarolic environments can be explained by the hydrochloric leaching of rock particles followed by the precipitation of low-solubility sulfides induced by the reaction of acid solutions with H2S at ambient temperatures. The elemental composition of native sulfur can be used to qualitatively estimate elemental abundances in low-temperature fumarolic gases.

Volcano–hydrothermal system of Ebeko volcano, Paramushir, Kuril Islands: Geochemistry and solute fluxes of magmatic chlorine and sulfur

Ebeko volcano at the northern part of Paramushir Island in the Kuril island arc produces frequent phreatic eruptions and relatively strong fumarolic activity at the summit area ~1000m above sea level (asl). The fumaroles are characterized by low-temperature, HCl- and S-rich gas and numerous hyper-acid pools (pH<1) without drains. At ~550m asl, in the Yurieva stream canyon, many hot (up to 87°C) springs discharge ultra-acidic (pH1–2) SO4–Cl water into the stream and finally into the Sea of Okhotsk. During quiescent stages of degassing, these fumaroles emit 1000–2000t/d of water vapor, <20t/d of SO2 and <5t/d of HCl. The measurement of acidic hot Yurieva springs shows that the flux of Cl and S, 60–80t/d each, is independent on the volcanic activity in the last two decades. Such high flux of Cl is among the highest ever measured in a volcano–hydrothermal system. Oxygen and hydrogen isotopic composition of water and Cl concentration for Yurieva springs show an excellent positive correlation, indicating a mixing between meteoric water and magmatic vapor. In contrast, volcanic gas condensates of Ebeko fumaroles do not show a simple mixing trend but rather a complicated data suggesting evaporation of the acidic brine. Temperatures calculated from gas compositions and isotope data are similar, ranging from 150 to 250°C, which is consistent with the presence of a liquid aquifer below the Ebeko fumarolic fields. Saturation indices of non-silicate minerals suggest temperatures ranging from 150 to 200°C for Yurieva springs. Trace elements (including REE) and Sr isotope composition suggest congruent dissolution of the Ebeko volcanic rocks by acidic waters. Waters of Yurieva springs and waters of the summit thermal fields (including volcanic gas condensates) are different in Cl/SO4 ratios and isotopic compositions, suggesting complicated boiling–condensation–mixing processes.

Subsurface structure of the northeastern fumarole field of the Ebeko Volcano (Paramushir Island) according to the data of geoelectrical and geochemical studies

The results of complex studies of the northeastern fumarole field of the Ebeko Volcano (Paramushir Island) are presented. The geochemical study of the thermal sources and potholes evidences the complex composition of the solutions: the high contents of certain chemical elements in the sources cannot be explained only by leaching from the host rocks. To identify the structural features that can lead to accumulation of elements in the thermal solutions, the geophysical study of the northeastern fumarole field of the volcano is carried out by frequency sounding, electric tomography, and temperature surveying along the profile. As a result, the structure of the subsurface space of the thermal field, the structure of the feeders, and the presence of a phase barrier for fluid separation are revealed. The complex of studies makes it possible to explain some features of the geochemical composition of the thermal sources and to describe the evolution of the fluids in the upper segment of the section.

The active volcanoes of Kamchatka and Paramushir Island, North Kurils in 2007

Eight strong eruptions of four Kamchatka volcanoes (Bezymyannyi, Klyuchevskoi, Shiveluch, and Karymskii) and Chikurachki Volcano on Paramushir Island, North Kurils took place in 2007. In addition, an explosive event occurred on Mutnovskii Volcano and increased fumarole activity was recorded on Avacha and Gorelyi volcanoes in Kamchatka and Ebeko Volcano on Paramushir Island, North Kurils. Thanks to close cooperation with colleagues involved in the Kamchatkan Volcanic Eruption Response Team (KVERT) project from the Elizovo Airport Meteorological Center and volcanic ash advisory centers in Tokyo, Anchorage, and Washington (Tokyo VAAC, Anchorage VAAC, and Washington VAAC), all necessary precautions were taken for flight safety near Kamchatka.

Increased activity on Ebeko Volcano, Paramushir I., North Kurils in 2005–2006

In recent years the gas hydrothermal activity of Ebeko Volcano has been characterized by a constant heat flow and a constant chemical composition of water and fumarole gases. The volcano’s activity suddenly increased on January 27, 2005. Two high-output steam-gas jets 5 m across formed in the Active Funnel of the North Crater. A new high-output, high-temperature, fumarole field originated in the funnel in July 2005. Changes have been recorded in the chemical composition of fumarole gases. Ratios between individual components of the gas were calculated, with the ratios being geochemical precursors of eruptions for the volcano under study. Based on these results and on the very fact of increased fumarole activity on Ebeko, an intermediate-term forecast of explosive eruptions has been developed. Atmospheric contamination by a toxic gas (hydrogen sulfide) is described. It was previously thought that toxic gases pose a short-lived threat only to the population of the town of Severo-Kuril’sk because of frequent strong winds prevailing there. It is shown that the presence of a snow cover during increased activity on Ebeko sharply enhances the hazard of contamination by toxic gases, the hazard being constant both on the volcano itself and in the Severo-Kuril’sk area.

Drilling at Santorini Volcano, Greece

Metalliferous hydrothermal systems and other volcanic manifestations related to subduction zones are well known from areas like the Aegean (Santorini), the Kuriles (at Ebeko volcano, for example), and off the Antarctic Peninsula (Deception Island). Iron‐rich deposits have been encountered at all these sites [Gorshkov, 1958; Elderfield, 1972]. However, direct observations through a cross section of such hydrothermal systems seem to be lacking, despite the existence of extensive studies over the last few decades of processes related to the genesis o f metalliferous hydrothermal systems, made partly through the international seafloor drilling program. It is apparent that such cross‐sectional observations could greatly advance our understanding of ore‐forming processes and hydrothermal systems. The Santorini island group in the southern Aegean Sea (Figure 1) is an ideal site for study, from both scientific and logistical points of view.

Results of geochemical monitoring of the activity of Ebeko volcano (Kurile Islands) used for eruption prediction

The monitoring of the state of active volcanoes, carried out using different parameters, including geochemical, is very important for studies of deep processes and geodynamics. All changes which occur within the crater before eruptions reflect the magma activation and depend on the deep structure of volcano. This paper gives the results of prolonged monitoring of Ebeko volcano, located in the contact zone between the oceanic and continental plates (the Kurile Island Arc). The geochemical method has been used as the basis for eruption prediction because the increase in the activity of the Ebeko in the period from 1963 to 1967 that ended in a phreatic eruption was not preceded by seismic preparation. Investigations carried out at Ebeko volcano give evidence that change of all the chosen geochemical parameters is a prognostic indicator of a forthcoming eruption. This change depends on the type of eruption, and the deep structure and hydrodynamic regime of the volcano.