Journal of Volcanology and Seismology最新文献

The period of more than twenty years in which recent movements in the Mountainous Altai were measured by methods of satellite geodesy includes various phases of the seismic process. A network consisting of 20 observing stations extends over a large area from Novosibirsk City in the north to the Mongolian border in the south, from the border with Kazakhstan in the west to the Sayan Mountains in the east. The Chuya earthquake of September 2003 divides, in a natural manner, the period of observation from 2000 to 2022 into several phases: the preseismic (2000‒2003), the coseismic (2003‒2004), the postseismic phase for the epicentral area of the Chuya earthquake (2004‒2013), and the interseismic phase for the other regions of the Mountainous Altai that have not been seriously affected by the earthquake (2000‒2022). The data supplied by multiyear measurements were analyzed using special programs of the most recent modifications. We have identified conspicuous features in the displacement fields during each phase: anomalous displacement rates before the Chuya earthquake, the coseismic displacements during the earthquake, postseismic effects in the epicentral zone, and slow tectonic movements. Our interpretation relied on 2D and 3D elastic and viscoelastic models of the crust. The depth of focus has been determined (14 km), as well as the two-meter relative right lateral displacement jump on the seismic fault. With a two-layered model, we obtained the value of viscosity in the lower crust for a variety of elastic modulus values η = 5 × 10¹⁹‒1.1 × 10²⁰ Pa s. The recent movements in that part of the Mountainous Altai which has not been affected by the Chuya earthquake were 0.8 mm/yr toward NNW. The rate of surface deformation in the southern mountainous part reached 2 × 10^–8/yr in the epoch 2000‒2022, which is an order of magnitude higher than that in the northern flat part of the area of study.

Volcanic eruptions can bring about lava flows, posing significant hazards and rare direct threats to human life, but they can also cause extensive damage to property and economic activities. Managing volcanic disasters demands swift and accurate information on the behaviour and evolution of lava flows, particularly regarding their extension, displacement, and trajectory. This study addresses numerical and laboratory modelling to understand the dynamics of a lava flow and its frontal advancement. Laboratory experiments of a lava flow analogue, exhibiting a non-Newtonian Herschel–Bulkley fluid behaviour, have been conducted. The fluid parameters at varying temperatures have been determined on the basis of the rheometer and thermal camera measurements. A flow of the Herschel–Bulkley fluid (the lava flow analogue with the fluid parameters determined from the laboratory experiments) is then simulated numerically using the Abaqus software, where a smoothed particle hydrodynamics method has been implemented. A run-out distance, frontal flow displacement, and flow velocity have been determined during laboratory and numerical modelling. When the fluid parameters measured at a constant temperature of 80°C are used, the numerical results diverge from the experimental results over time. To mimic closely the dynamics of the lava flow analogue inferred from the laboratory experiment with its dynamics in the numerical modelling, time-dependent adjustments to the Herschel–Bulkley fluid parameters determined at lower temperatures have been introduced by changing their values during a numerical simulation. This study underscores the importance of constraining parameters of numerical models by the values obtained from laboratory measurements.

This study reports comprehensive research (archeological, archaeo- and paleo-seismological, as well as georadar profiling), which enabled us to find out the cause of destruction for the South Churubash settlement (a big manor in the chora around the town of Nymphaion) in eastern Crimea. A strong seismic event whose possible rupture went along the southwestern boundary of the Churubash Liman, which is a segment of the Parpach–Taman active fault, led to the formation of landslide bodies southwest of the rupture. The nearly north–south plane of scar for one of these has traversed the ancient settlement through its middle, having produced a visible flexure in the juvenile soil of this archeological monument—an earthquake-induced gravitational deformation. Large seismic slip at the fault plane had destroyed all structures and led to large deformations in the lower rows of the masonry: tilts, shifts, and rotations of parts of the walls—earthquake-induced inertial deformations. Considering that the earthquake rupture was nearby, and that all houses have been destroyed in the settlement, we hypothesize that the manor was caught in the epicentral zone of an ancient earthquake where the intensity of seismic motion was at least Io ≥ IX. Judging by the findings of amphorae brands, black glazed pottery, as well as of a Bosporus coin, this large manor in the chora of Nymphaion came to the end of its existence owing to a strong earthquake and a fire in the beginning of the fourth quarter of the 4th century BC. We may have previously observed traces of this earthquake in Nymphaion: as an example, the structures of Nymphaion dating back to the 5th—4th centuries BC had been completely or partly destroyed. Further surveys of active geological structures and archeological monuments would enable a more accurate parameterization of the seismic event identified in this study, which would serve the purpose of a more accurate assessment of earthquake hazard for the Crimean Peninsula.

This paper presents the first results from the monitoring of local seismicity in Severnaya Zemlya from the end of 2016 to 2023 inclusive as recorded by a single permanent seismic station installed on Bolshevik Island. A total of 73 local seismic events have been identified with P and S phases. We considered the question whether these events could be classified (earthquakes or icequakes) by comparing waveforms and spectral-temporal analysis diagrams with regional earthquakes that have occurred in the archipelago area. The spatio-temporal distribution and the rate of migration for the events show that glacial events can arise by stress release in glaciers as shallow crustal earthquakes occur within ~30 km. It is shown that, when a seismograph network is difficult to deploy, even a single permanent seismic station can furnish useful information on glacial events and crustal earthquakes.

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.

The Tonga-Kermadec subduction zone lies between the Pacific and Australian plates. The location shows the highest rate of subduction for the Pacific plate and a dominant tension. Two great earthquakes occurred in the region in 2006 and 2009 whose magnitudes were M_w = 8.0 and 8.1. There are about 170 islands around the Tonga subduction zone; these islands are volcanic centers that have been regularly in eruption during the last several decades. The present study presents the results from the determination of time-dependent variations in the slope of the recurrence curve (the b-value) at the Tonga subduction zone during 2005–2022, and depth-dependent variations in b. The time-dependent variations in b reflect the general tendency of great earthquakes occurring upon the background of lower b-values in the surface layer only, at depths of 0–100 km. The comparison between the depth-dependent variations in b and the tectonic model for the Toga subduction zone implies the hypothesis that lower b-values may reflect greater stresses in the upper part of the plunging plate due to its bending. Higher b-values seem to be connected to tensional mechanisms. A region of higher b-values at depths of 90–100 km has been identified for the Tonga subduction zone, as well as for other subduction zones, which can be related to the presence of a magmatic front at these depths, which is related to active volcanism.

This paper is concerned with the distribution of heat flow in the Baikal Rift Zone, the Shanxi-Liaohe Rift, the Jordan Rift, and in the Orly (Storoya) Trough in the northern Svalbard plate, as well as in the rift zone of Iceland. One notes an asymmetry in heat flow about the rift axial line compared with adjacent areas upon the background of its higher value. The origin of this asymmetry is due, not only to differences in the permeability of the faults in the sides of the rift structure, but also to planet-wide factors, in particular, the Coriolis force. The north–south rift structures considered here are situated in the northern hemisphere; their eastern flanksshow increased heat flow compared with the western flanks, and this is in agreement with the Coriolis force vector in the Earth’s northern hemisphere. The geothermal asymmetry in oceanic crustal divergent zones as noted previously is also seen in pull-apart structures of continental rift zones.

This work is concerned with classification and study of the composition and properties of hydrothermal zeolites from the Yagodninskoe deposit, (Kamchatka) which were formed in volcanic rocks. The study involved X-ray phase analysis and X-ray fluorescence, optical and scanning electron microscopy. We determined specific syrface AREA the pore size distribution, as well as cation exchange capacity in zeolites. The study resulted in the identification of four main rock types at the deposit: the original unaltered perlites, zeolites rock, zeolitized tuffs, as well as poorly zeolitized tuff breccias. The Content of zeolite group minerals reaches 70%. The minerals mostly include clinoptilolite and, to a lesser degree, mordenite, stilbite, and heulandite. The zeolites are of the alkaline type, with the cation exchange capacity equal to 205.9 mg-equi/100 g. It has been found that these zeolites were mostly formed from perlites and tuff breccias. It is pointed out that the Yagodninskoe zeolites are high quality minerals, and make a promising object of further exploration.

We have carried out a correlation analysis to study relationships between the trace element (TE) composition of mud-volcanic and carbon dioxide fluids in the Greater Caucasus on the one hand and the chemical composition of upper, middle, and lower crust, as well as various kinds of biota on the other hand. It has turned out to be possible to relate the roots of the associated fluid flows with definite stages of the Earth’s crust, as well as to point out, in several cases, the kind of the dominant original organic matter. The roots of both carbon dioxide fluids and mud-volcanic fluids were shown to reside in the middle crust. We have compared correlative relationships for deep-seated fluids in the Caucasus with those for oils in several major oil-gas basins in Russia and in the fluid systems of Kamchatka.

We analyzed published datasets relating to the composition of glasses from melt inclusions in minerals of volcanics from the Eastern Volcanic Belt and Sredinny Range of Kamchatka. A significant difference was found between the distribution of silica concentration in the rocks and melts: intermediate and basic compositions are most common among the rocks, whereas the glasses in melt inclusions are predominantly acidic. The distribution of major and trace elements was analyzed. It was shown that the contents of some elements are environment-specific (e.g., Nb and light REEs). We identified trace element ratios in melts that most strongly correlate with the geodynamic setting.