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

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.

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.

Приводятся результаты применения авторской компьютерной технологии для интерпретации материалов комплексных исследований подводных вулканов 2.7 и 2.8, расположенных к западу от юго-западного берега о. Онекотан в Курильской островной дуге. В результате проведенных исследований выполнена оценка магнитных свойств горных пород в естественном залегании и установлено, что наиболее намагниченными являются юго-западные склоны подводного вулкана 2.8, эффективная намагниченность которых достигает 2 А/м. Сделаны предположения о юго-западном направлении подводящего канала подводного вулкана 2.7 и субвертикальном, юго-западном и юго-восточном направлениях подводящих каналов подводного вулкана 2.8. Отмечено наличие на глубине около 650 м периферического магматического очага вулкана 2.8.

The paper provides results from application of designed modern computer techniques for interpretation of materials from complex geophysical investigation of submarine volcanoes 2.7 and 2.8, which are located west of the south-western coast of Onekotan Island in the Kurile island arc. The research resulted in estimation of rock magnetic properties in natural deposits and revealed that the south-western flanks of submarine volcano 2.8 are the most magnetized with their productive magnetization of about 2 A/m. The authors suggested that the feeding channels of volcano 2.7 stretch southwest, while the feeding channels of volcano 2.8 stretch subverticaly, southwest and southeast. A peripheral magma chamber of the volcano was revealed at the depth of about 650 m.

Во время полевых работ были исследованы базальты Толбачинского дола и их магнитные свойства. По химическому и петрофизическому составу породы Толбачинского дола относятся к магнезиальным (например, прорывов 1941 г. и 1975 г.) и глиноземистым базальтам (например, конуса Клешня, даек и поля Магуськина). Выяснено, что для пород Толбачинского дола величина магнитной восприимчивости глиноземистых базальтов ниже, чем магнезиальных.