Investigation of shocked materials provides unique information about behavior of substances in ex... more Investigation of shocked materials provides unique information about behavior of substances in extreme thermodynamic conditions. Near surface nuclear tests have induced multiple transformations of affected soils. Examination of nuclear glasses and relics of entrapped minerals provides a unique database on their behavior under an intense temperature flash. In this work, several types of nuclear fallout particles from historic tests at the Semipalatinsk test site are investigated using complementary analytical methods. Distribution of radionuclides in all types of samples is highly heterogeneous; domains with high content of radionuclides are often intermixed with non-active materials. There is no general correlation between chemical composition of the glassy matrix and content of radionuclides. In aerodynamic fallout, the main fraction of radionuclides is trapped in the outer glassy shell. Relics of quartz grains are always devoid of radionuclides, while glass regions of high activit...
The Fuego de Colima volcano (Mexico) showed a complex eruptive behaviour with periods of rapid an... more The Fuego de Colima volcano (Mexico) showed a complex eruptive behaviour with periods of rapid and slow lava dome growth, punctuated by explosive activity. We reconstructed the weekly discharge rate average between 1998 and 2018 by means of satellite thermal data integrated with published discharge rate data. By using spectral and wavelet analysis, we found a multi-year long-, multi-month intermediate-, and multi-week short-term cyclic behaviour during the period of the investigated eruptive activity, as those of many others dome-forming volcanoes. We use numerical modelling in order to investigate the non-linear cyclic eruptive behaviour considering a magma feeding system composed of a dual or a single magma chamber connected to the surface through an elastic dyke evolving into a cylinder conduit in the shallowest part. We investigated the cases in which the periodicity is controlled by i) the coupled deep-shallow magma reservoirs, ii) the single shallow chamber, and iii) the elastic shallow dyke when is fed by a fixed influx rate or a constant pressure. The model outputs indicate that the observed multi-year periodicity (1.5-2.5 years) can be described by the fluctuations controlled by a shallow magma chamber with a volume of 20-50 km 3 coupled with a deep reservoir of 500 km 3 , connected through a deep elastic dyke. The multi-month periodicity (ca. 5-10 months) appears to be controlled by the shallow magma chamber for the same range of volumes. The short-term multi-week periodicity (ca. 2.5-5 weeks) can be reproduced considering a fixed influx rate or constant pressure at the base of the shallower dyke. This work provides new insights on the non-linear cyclic behaviour of Fuego de Colima, and a general framework for the comprehension of eruptive behaviour of andesitic volcanoes.
To the present moment there are a lot of ways to define heat conductivity and thermal diffusivity... more To the present moment there are a lot of ways to define heat conductivity and thermal diffusivity of solid bodies. The schemes of determining heat conductivity, which use transient methods, usually include a heater and a cooler. The sample is placed in between them. The temperature and temperature differential is determined using several thermocouples. The authors present a method of determining the thermal characteristics of a sample in the form of a rectangular plate, allowing to apply only one thermocouple, which leads to a simple analytical expression for thermal diffusivity. The described method provides high-precision determination of thermal diffusivity of the body of small size and with the accuracy sufficient for practice — conductivity coefficient. The method uses a simple mathematical model and minimal hardware resources compared to other methods. The exception is the heat-insulating materials. The determination of their thermal conductivity using this method can lead to poor accuracy.
, except for brief excerpts in connection with reviews or scholarly analysis. Use in connection w... more , except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. springer.com
An unsteady model which describes the eruption dynamics of high-viscosity gas-saturated magmas an... more An unsteady model which describes the eruption dynamics of high-viscosity gas-saturated magmas and generalizes the steady model outlined in [1] is proposed. The evolution of the eruption in the transition between various steady regimes is investigated. It is shown that in this process undamped oscillations of the magma flow rate with a period of from tens of minutes to several hours can arise .
Summary Lava domes form during effusive eruptions due to an extrusion of highly viscous magmas fr... more Summary Lava domes form during effusive eruptions due to an extrusion of highly viscous magmas from volcanic vents. In this paper we present a numerical study of the lava dome growth at Volcán de Colima, Mexico during 2007-2009. The mathematical model treats the lava dome extrusion dynamics as a thermo-mechanical problem. The equations of motion, continuity, and heat transfer are solved with the relevant boundary and initial conditions in the assumption that magma viscosity depends on the volume fraction of crystals and temperature. We perform several sets of numerical experiments to analyse the internal structure of the lava dome (i.e., the distributions of the temperature, crystal content, viscosity, and velocity) depending on various heat sources and thermal boundary conditions. Although the lava dome growth at Volcán de Colima during short (a few months) dome-building episodes can be explained by an isothermal model of lava extrusion with the viscosity depending on the volume fr...
The original version of this article contained an error in the name of I. S. Utkin which was inco... more The original version of this article contained an error in the name of I. S. Utkin which was incorrectly given as I. V. Utkin. Furthermore, there was an error in Affiliation 5, which was incorrectly given as '
We present a numerical model of trace-element oscillatory zoning patterns formed when zircon crys... more We present a numerical model of trace-element oscillatory zoning patterns formed when zircon crystallizes from silicate melt, which is also appropriate for other accessory phases with known partition and diffusion coefficients and saturation conditions. The model accounts for diffusion-controlled accessory mineral growth and the equilibrium crystallization of major mineral phases. Consideration of recent, experimentally determined dependencies of partition coefficients on temperature, we find that thermal changes provide the simplest explanations of oscillatory zoning in accessory minerals. Numerical experiments with different cooling rates explore different crystallization scenarios with and without the precipitation of other phases and/or the interface reaction of phosphorus (P) and yttrium (Y) to form xenotime. However, these processes are monotonically related to growth rate and do not cause oscillations. Minor 3-10 °C variations in temperature do not result in zircon dissolution, but strongly influence zircon growth and lead to variations in coeval Y, Hf, and rare earth element (REE) concentrations of up to a factor of two, comparable to those observed in nature. Such temperature variations may be very common in any igneous body in response to external factors such as replenishment by hotter magmas or convection. More significant temperature fluctuations may result in initial minor dissolution at higher temperatures during a mafic recharge event but with continuous growth afterward. At high temperature (>~850 °C) the amplitude of oscillations is relatively small that confirms observations of both less common oscillatory zoning in hot and dry volcanic rhyolites and abundant oscillations in plutonic zircons and in zircons in cold and wet crystal-rich mushes. Additional oscillations in zircon are modeled in response to oscillations of pressure on the order of ±35-50 bars, causing water concentration fluctuations of ±0.1 wt% in water-saturated melt cells with a gas bubble. These variations cause variations of Zr diffusion and zircon growth rates. Such fluctuations could result from pressure oscillations due to recharge and convection in the magma chamber. All simulated runs generate smoothed oscillatory growth zoning; similar patterns found in nature may not necessarily require post-growth intracrystalline diffusion.
<p>Fagradalsfjall eruption showed a remarkable pulsatory magma discharge activity i... more <p>Fagradalsfjall eruption showed a remarkable pulsatory magma discharge activity in Jul-Aug 2021, with a characteristic timescale of ~36 hours (with cycles varying from 17 to 76 hours) and a duration of lava outflow from the crater of 10 to 70 hours. Active lava discharge coincides with the presence of both shallow and deep volcanic tremors that stops abruptly as soon as the active phase of the cycle finishes. The initial phase of each eruption cycle is characterized by some shifts of the tremor source between a depth of ~ 5 km and a shallow level, active degassing, and appearance of fresh lava at the top of the crater. Deep tremor source might be continuously active.</p><p>We propose that the pulsatory activity is caused by the dynamics of magma flow in a feeding dike. The model assumes purely elastic wall-rocks rheology and Newtonian temperature-dependent magma viscosity. Elastic displacement of host rocks is calculated by means of the analytical solution for an elliptic cavity subject to fluid overpressure. We assume that surrounding rocks temperature is linearly increasing with depth and the heat transfer from the magma following Newton’s law. The influx of the magma at the base of the dike is controlled by the dike overpressure. For reasonable values of governing parameters, the system shows pulsatory activity in accordance with the observed timescales. During low discharge rate magma viscosity in the upper part of the dike increases dramatically, magma flow stops, and the dike starts to inflate at depth storing large amounts of magma. As the pressure increases the flow of the fresh hot magma destroys the plug and discharge episode occurs. The dike deflates and the flow rate decreases leading to consequent cooling of the magma and blockage of the dike.</p><p>Parametric study reveals the influence of controlling parameters (magma influx rate, elastic modulus of rocks, heat exchange coefficient end others) on the period of discharge and the presence of pulsatory activity.</p>
... Preface The andesitic dome-building eruption of Soufriere Hills Volcano has wreaked havoc on ... more ... Preface The andesitic dome-building eruption of Soufriere Hills Volcano has wreaked havoc on the small Caribbean island of Montser ... About half of this' Emerald Isle'has been rendered barren and uninhabitable, almost two-thirds of the original population has left, and ...
Предложена математическая модель процесса легирования поверхности металла с помощью импульсного л... more Предложена математическая модель процесса легирования поверхности металла с помощью импульсного лазерного излучения, в которой учитывается зависимость температурного градиента поверхностного натяжения от концентрации поверхностно-активного вещества в расплаве и температуры разогрева. Проведено численное моделирование, результаты которого выявили развитие многовихревых течений, способствующих проникновению легирующего материала в глубину расплава.
Investigation of shocked materials provides unique information about behavior of substances in ex... more Investigation of shocked materials provides unique information about behavior of substances in extreme thermodynamic conditions. Near surface nuclear tests have induced multiple transformations of affected soils. Examination of nuclear glasses and relics of entrapped minerals provides a unique database on their behavior under an intense temperature flash. In this work, several types of nuclear fallout particles from historic tests at the Semipalatinsk test site are investigated using complementary analytical methods. Distribution of radionuclides in all types of samples is highly heterogeneous; domains with high content of radionuclides are often intermixed with non-active materials. There is no general correlation between chemical composition of the glassy matrix and content of radionuclides. In aerodynamic fallout, the main fraction of radionuclides is trapped in the outer glassy shell. Relics of quartz grains are always devoid of radionuclides, while glass regions of high activit...
The Fuego de Colima volcano (Mexico) showed a complex eruptive behaviour with periods of rapid an... more The Fuego de Colima volcano (Mexico) showed a complex eruptive behaviour with periods of rapid and slow lava dome growth, punctuated by explosive activity. We reconstructed the weekly discharge rate average between 1998 and 2018 by means of satellite thermal data integrated with published discharge rate data. By using spectral and wavelet analysis, we found a multi-year long-, multi-month intermediate-, and multi-week short-term cyclic behaviour during the period of the investigated eruptive activity, as those of many others dome-forming volcanoes. We use numerical modelling in order to investigate the non-linear cyclic eruptive behaviour considering a magma feeding system composed of a dual or a single magma chamber connected to the surface through an elastic dyke evolving into a cylinder conduit in the shallowest part. We investigated the cases in which the periodicity is controlled by i) the coupled deep-shallow magma reservoirs, ii) the single shallow chamber, and iii) the elastic shallow dyke when is fed by a fixed influx rate or a constant pressure. The model outputs indicate that the observed multi-year periodicity (1.5-2.5 years) can be described by the fluctuations controlled by a shallow magma chamber with a volume of 20-50 km 3 coupled with a deep reservoir of 500 km 3 , connected through a deep elastic dyke. The multi-month periodicity (ca. 5-10 months) appears to be controlled by the shallow magma chamber for the same range of volumes. The short-term multi-week periodicity (ca. 2.5-5 weeks) can be reproduced considering a fixed influx rate or constant pressure at the base of the shallower dyke. This work provides new insights on the non-linear cyclic behaviour of Fuego de Colima, and a general framework for the comprehension of eruptive behaviour of andesitic volcanoes.
To the present moment there are a lot of ways to define heat conductivity and thermal diffusivity... more To the present moment there are a lot of ways to define heat conductivity and thermal diffusivity of solid bodies. The schemes of determining heat conductivity, which use transient methods, usually include a heater and a cooler. The sample is placed in between them. The temperature and temperature differential is determined using several thermocouples. The authors present a method of determining the thermal characteristics of a sample in the form of a rectangular plate, allowing to apply only one thermocouple, which leads to a simple analytical expression for thermal diffusivity. The described method provides high-precision determination of thermal diffusivity of the body of small size and with the accuracy sufficient for practice — conductivity coefficient. The method uses a simple mathematical model and minimal hardware resources compared to other methods. The exception is the heat-insulating materials. The determination of their thermal conductivity using this method can lead to poor accuracy.
, except for brief excerpts in connection with reviews or scholarly analysis. Use in connection w... more , except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. springer.com
An unsteady model which describes the eruption dynamics of high-viscosity gas-saturated magmas an... more An unsteady model which describes the eruption dynamics of high-viscosity gas-saturated magmas and generalizes the steady model outlined in [1] is proposed. The evolution of the eruption in the transition between various steady regimes is investigated. It is shown that in this process undamped oscillations of the magma flow rate with a period of from tens of minutes to several hours can arise .
Summary Lava domes form during effusive eruptions due to an extrusion of highly viscous magmas fr... more Summary Lava domes form during effusive eruptions due to an extrusion of highly viscous magmas from volcanic vents. In this paper we present a numerical study of the lava dome growth at Volcán de Colima, Mexico during 2007-2009. The mathematical model treats the lava dome extrusion dynamics as a thermo-mechanical problem. The equations of motion, continuity, and heat transfer are solved with the relevant boundary and initial conditions in the assumption that magma viscosity depends on the volume fraction of crystals and temperature. We perform several sets of numerical experiments to analyse the internal structure of the lava dome (i.e., the distributions of the temperature, crystal content, viscosity, and velocity) depending on various heat sources and thermal boundary conditions. Although the lava dome growth at Volcán de Colima during short (a few months) dome-building episodes can be explained by an isothermal model of lava extrusion with the viscosity depending on the volume fr...
The original version of this article contained an error in the name of I. S. Utkin which was inco... more The original version of this article contained an error in the name of I. S. Utkin which was incorrectly given as I. V. Utkin. Furthermore, there was an error in Affiliation 5, which was incorrectly given as '
We present a numerical model of trace-element oscillatory zoning patterns formed when zircon crys... more We present a numerical model of trace-element oscillatory zoning patterns formed when zircon crystallizes from silicate melt, which is also appropriate for other accessory phases with known partition and diffusion coefficients and saturation conditions. The model accounts for diffusion-controlled accessory mineral growth and the equilibrium crystallization of major mineral phases. Consideration of recent, experimentally determined dependencies of partition coefficients on temperature, we find that thermal changes provide the simplest explanations of oscillatory zoning in accessory minerals. Numerical experiments with different cooling rates explore different crystallization scenarios with and without the precipitation of other phases and/or the interface reaction of phosphorus (P) and yttrium (Y) to form xenotime. However, these processes are monotonically related to growth rate and do not cause oscillations. Minor 3-10 °C variations in temperature do not result in zircon dissolution, but strongly influence zircon growth and lead to variations in coeval Y, Hf, and rare earth element (REE) concentrations of up to a factor of two, comparable to those observed in nature. Such temperature variations may be very common in any igneous body in response to external factors such as replenishment by hotter magmas or convection. More significant temperature fluctuations may result in initial minor dissolution at higher temperatures during a mafic recharge event but with continuous growth afterward. At high temperature (>~850 °C) the amplitude of oscillations is relatively small that confirms observations of both less common oscillatory zoning in hot and dry volcanic rhyolites and abundant oscillations in plutonic zircons and in zircons in cold and wet crystal-rich mushes. Additional oscillations in zircon are modeled in response to oscillations of pressure on the order of ±35-50 bars, causing water concentration fluctuations of ±0.1 wt% in water-saturated melt cells with a gas bubble. These variations cause variations of Zr diffusion and zircon growth rates. Such fluctuations could result from pressure oscillations due to recharge and convection in the magma chamber. All simulated runs generate smoothed oscillatory growth zoning; similar patterns found in nature may not necessarily require post-growth intracrystalline diffusion.
<p>Fagradalsfjall eruption showed a remarkable pulsatory magma discharge activity i... more <p>Fagradalsfjall eruption showed a remarkable pulsatory magma discharge activity in Jul-Aug 2021, with a characteristic timescale of ~36 hours (with cycles varying from 17 to 76 hours) and a duration of lava outflow from the crater of 10 to 70 hours. Active lava discharge coincides with the presence of both shallow and deep volcanic tremors that stops abruptly as soon as the active phase of the cycle finishes. The initial phase of each eruption cycle is characterized by some shifts of the tremor source between a depth of ~ 5 km and a shallow level, active degassing, and appearance of fresh lava at the top of the crater. Deep tremor source might be continuously active.</p><p>We propose that the pulsatory activity is caused by the dynamics of magma flow in a feeding dike. The model assumes purely elastic wall-rocks rheology and Newtonian temperature-dependent magma viscosity. Elastic displacement of host rocks is calculated by means of the analytical solution for an elliptic cavity subject to fluid overpressure. We assume that surrounding rocks temperature is linearly increasing with depth and the heat transfer from the magma following Newton’s law. The influx of the magma at the base of the dike is controlled by the dike overpressure. For reasonable values of governing parameters, the system shows pulsatory activity in accordance with the observed timescales. During low discharge rate magma viscosity in the upper part of the dike increases dramatically, magma flow stops, and the dike starts to inflate at depth storing large amounts of magma. As the pressure increases the flow of the fresh hot magma destroys the plug and discharge episode occurs. The dike deflates and the flow rate decreases leading to consequent cooling of the magma and blockage of the dike.</p><p>Parametric study reveals the influence of controlling parameters (magma influx rate, elastic modulus of rocks, heat exchange coefficient end others) on the period of discharge and the presence of pulsatory activity.</p>
... Preface The andesitic dome-building eruption of Soufriere Hills Volcano has wreaked havoc on ... more ... Preface The andesitic dome-building eruption of Soufriere Hills Volcano has wreaked havoc on the small Caribbean island of Montser ... About half of this' Emerald Isle'has been rendered barren and uninhabitable, almost two-thirds of the original population has left, and ...
Предложена математическая модель процесса легирования поверхности металла с помощью импульсного л... more Предложена математическая модель процесса легирования поверхности металла с помощью импульсного лазерного излучения, в которой учитывается зависимость температурного градиента поверхностного натяжения от концентрации поверхностно-активного вещества в расплаве и температуры разогрева. Проведено численное моделирование, результаты которого выявили развитие многовихревых течений, способствующих проникновению легирующего материала в глубину расплава.
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