scholarly journals Explosive-effusive volcanic eruption transitions caused by sintering

2020 ◽  
Vol 6 (39) ◽  
pp. eaba7940 ◽  
Author(s):  
Fabian B. Wadsworth ◽  
Edward W. Llewellin ◽  
Jérémie Vasseur ◽  
James E. Gardner ◽  
Hugh Tuffen
Keyword(s):  
Volcanic Activity ◽  
Numerical Models ◽  
Volcanic Eruptions ◽  
Upper Crust ◽  
Rhyolitic Magma ◽  
Silicic Volcanic ◽  
Geochemical Models ◽  
Effusive Eruptions ◽  
Textural Evidence ◽  
New Framework

Silicic volcanic activity has long been framed as either violently explosive or gently effusive. However, recent observations demonstrate that explosive and effusive behavior can occur simultaneously. Here, we propose that rhyolitic magma feeding subaerial eruptions generally fragments during ascent through the upper crust and that effusive eruptions result from conduit blockage and sintering of the pyroclastic products of deeper cryptic fragmentation. Our proposal is supported by (i) rhyolitic lavas are volatile depleted; (ii) textural evidence supports a pyroclastic origin for effusive products; (iii) numerical models show that small ash particles ≲10−5 m can diffusively degas, stick, and sinter to low porosity, in the time available between fragmentation and the surface; and (iv) inferred ascent rates from both explosive and apparently effusive eruptions can overlap. Our model reconciles previously paradoxical observations and offers a new framework in which to evaluate physical, numerical, and geochemical models of Earth’s most violent volcanic eruptions.

scholarly journals Near-real-time volcanic cloud monitoring: insights into global explosive volcanic eruptive activity through analysis of Volcanic Ash Advisories

2021 ◽  
Vol 83 (2) ◽  
Author(s):  
S. Engwell ◽  
L. Mastin ◽  
A. Tupper ◽  
J. Kibler ◽  
P. Acethorp ◽  
...  
Keyword(s):  
Real Time ◽  
Volcanic Activity ◽  
Volcanic Ash ◽  
Source Parameters ◽  
Volcanic Eruptions ◽  
Volcanic Hazards ◽  
Process Data ◽  
Cloud Monitoring ◽  
Satellite Sensors ◽  
Volcanic Cloud

AbstractUnderstanding the location, intensity, and likely duration of volcanic hazards is key to reducing risk from volcanic eruptions. Here, we use a novel near-real-time dataset comprising Volcanic Ash Advisories (VAAs) issued over 10 years to investigate global rates and durations of explosive volcanic activity. The VAAs were collected from the nine Volcanic Ash Advisory Centres (VAACs) worldwide. Information extracted allowed analysis of the frequency and type of explosive behaviour, including analysis of key eruption source parameters (ESPs) such as volcanic cloud height and duration. The results reflect changes in the VAA reporting process, data sources, and volcanic activity through time. The data show an increase in the number of VAAs issued since 2015 that cannot be directly correlated to an increase in volcanic activity. Instead, many represent increased observations, including improved capability to detect low- to mid-level volcanic clouds (FL101–FL200, 3–6 km asl), by higher temporal, spatial, and spectral resolution satellite sensors. Comparison of ESP data extracted from the VAAs with the Mastin et al. (J Volcanol Geotherm Res 186:10–21, 2009a) database shows that traditional assumptions used in the classification of volcanoes could be much simplified for operational use. The analysis highlights the VAA data as an exceptional resource documenting global volcanic activity on timescales that complement more widely used eruption datasets.

scholarly journals Volcanic activity sparks the Arctic Oscillation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weizheng Qu ◽  
Fei Huang ◽  
Jinping Zhao ◽  
Ling Du ◽  
Yong Cao
Keyword(s):  
Volcanic Activity ◽  
Volcanic Eruption ◽  
Arctic Oscillation ◽  
Polar Vortex ◽  
Volcanic Eruptions ◽  
The Arctic ◽  
Vortex System ◽  
Significant Fluctuation ◽  
The Arctic Oscillation

AbstractThe parasol effect of volcanic dust and aerosol caused by volcanic eruption results in the deepening and strengthening of the Arctic vortex system, thus stimulating or strengthening the Arctic Oscillation (AO). Three of the strongest AOs in more than a century have been linked to volcanic eruptions. Every significant fluctuation of the AO index (AOI = ΔH_middle latitudes − ΔH_Arctic) for many years has been associated with a volcanic eruption. Volcanic activity occurring at different locations in the Arctic vortex circulation will exert different effects on the polar vortex.

Improving correlation accuracy of crashworthiness applications by combining the CORA and MADM methods

2021 ◽  
pp. 095440702110696
Author(s):  
Christophe Bastien ◽  
Alexander Diederich ◽  
Jesper Christensen ◽  
Shahab Ghaleb
Keyword(s):  
Numerical Models ◽  
Monotonic Functions ◽  
Virtual Test ◽  
Industry Standard ◽  
Discrepancy Method ◽  
Original Equipment Manufacturers ◽  
The Relationship ◽  
Correlation Accuracy ◽  
New Framework ◽  
Selection Of

With the increasing use of Computer Aided Engineering, it has become vital to be able to evaluate the accuracy of numerical models. This research poses the problem of selection of the most accurate and relevant correlation solution to a set of corridor variations. Specific methods such as CORA, widely accepted in industry, are developed to objectively evaluate the correlation between monotonic functions, while the Minimum Area Discrepancy Method, or MADM, is the only method to address the correlation of non-injective mathematical variations, usually related to force/acceleration versus displacement problems. Often, it is not possible to differentiate objectively various solutions proposed by CORA, which this paper proposes to answer. This research is original, as it proposes a new innovative correlation optimisation framework, which can select the best CORA solution by including MADM as a subsequent process. The paper and the methods are rigorous, having used an industry standard driver airbag computer model, built virtual test corridors and compared the relationship between different CORA and MADM ratings from 100 Latin Hypercube samples. For the same CORA value of ‘1’ (perfect correlation), MADM was capable to objectively differentiate between 13 of them and provide the best correlation possible. The paper has recommended the MADM settings n = 1; m = 2 or n = 3; m = 2 for a congruent relationship with CORA. As MADM is performed subsequently, this new framework can be implemented in already existing industrial processes and provide automotive manufacturers and Original Equipment Manufacturers (OEM) with a new tool to generate more accurate computer models.

Ensemble-based data assimilation of volcanic aerosols using FALL3D+PDAF

2021 ◽  
Author(s):  
Leonardo Mingari ◽  
Andrew Prata ◽  
Federica Pardini
Keyword(s):  
Data Assimilation ◽  
Information Transfer ◽  
High Performance ◽  
Volcanic Ash ◽  
Numerical Models ◽  
Volcanic Eruptions ◽  
Column Height ◽  
Eruption Column ◽  
Operational Environment ◽  
Assimilation System

<p>Modelling atmospheric dispersion and deposition of volcanic ash is becoming increasingly valuable for understanding the potential impacts of explosive volcanic eruptions on infrastructures, air quality and aviation. The generation of high-resolution forecasts depends on the accuracy and reliability of the input data for models. Uncertainties in key parameters such as eruption column height injection, physical properties of particles or meteorological fields, represent a major source of error in forecasting airborne volcanic ash. The availability of nearly real time geostationary satellite observations with high spatial and temporal resolutions provides the opportunity to improve forecasts in an operational context. Data assimilation (DA) is one of the most effective ways to reduce the error associated with the forecasts through the incorporation of available observations into numerical models. Here we present a new implementation of an ensemble-based data assimilation system based on the coupling between the FALL3D dispersal model and the Parallel Data Assimilation Framework (PDAF). The implementation is based on the last version release of FALL3D (versions 8.x) tailored to the extreme-scale computing requirements, which has been redesigned and rewritten from scratch in the framework of the EU Center of Excellence for Exascale in Solid Earth (ChEESE). The proposed methodology can be efficiently implemented in an operational environment by exploiting high-performance computing (HPC) resources. The FALL3D+PDAF system can be run in parallel and supports online-coupled DA, which allows an efficient information transfer through parallel communication. Satellite-retrieved data from recent volcanic eruptions were considered as input observations for the assimilation system.</p>

A model for Archean tectonism. Part 2. Numerical models of vertical tectonism in greenstone belts

1980 ◽  
Vol 17 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Jean-Claude Mareschal ◽  
Gordon F. West
Keyword(s):  
Numerical Models ◽  
Volcanic Eruptions ◽  
Crustal Rocks ◽  
Tectonic Model ◽  
Mechanical Evolution ◽  
Accumulated Strain ◽  
Lava Sequence ◽  
Order Of Magnitude ◽  
Greenstone Belts ◽  
Horizontal Temperature Gradients

A tectonic model that attempts to explain common features of Archean geology is investigated. The model supposes the accumulation, by volcanic eruptions, of a thick basaltic pile on a granitoid crust. The thermal blanketing effect of this lava raises the temperature of the granitic crust and eventually softens it enough that gravitational slumping and downfolding of the lava follows.Numerical models of the thermal and mechanical evolution of a granitoid crust covered with a thick lava sequence indicate that such an evolution is possible when reasonable assumptions are made about the temperature dependence of the viscosity in crustal rocks. These models show the lava sinking in relatively narrow regions while wider granite diapirs appear in between. The convection produces strong horizontal temperature gradients that may cause lateral changes in metamoprhic facies. A one order of magnitude drop in accumulated strain occurs between the granite–basalt interface and the center of the granite diaper at a depth of 10–15 km.

SedCas_Volcano: Simulating decadal patterns of lahar hazard and sediment transfer following volcanic disturbance in the Belham River Valley, Montserrat 

2021 ◽  
Author(s):  
James Christie ◽  
Georgina Bennett ◽  
Jacob Hirschberg ◽  
Jenni Barclay ◽  
Richard Herd
Keyword(s):  
Volcanic Activity ◽  
Vegetation Cover ◽  
Volcanic Eruptions ◽  
River Valley ◽  
Sediment Supply ◽  
Recovery Cycle ◽  
Frequency Distributions ◽  
Volcanic Disturbance ◽  
Multi Phase ◽  
Disturbance Recovery

<p>Explosive volcanic eruptions are among the most significant natural disturbances to landscapes on Earth. The widespread and rapid influx of pyroclastic sediment, together with subsequent changes to topography and vegetation cover, drives markedly heightened runoff responses to rainfall and increased downstream water and sediment fluxes; principally by way of hazardous lahars. The nature and probability of lahar occurrence under given rainfall conditions evolves as the landscape responds and subsequently recovers following the disturbance. The relationship between varying sediment supply, rainfall patterns, vegetation cover and lahar activity is complex, and impedes forecasting efforts made in the interest of hazard and land use management. Thus, developing an improved understanding of how these systems evolve in response to volcanic eruptions is of high importance.</p><p>Here we present SedCas_Volcano[MOU1] , a conceptual sediment cascade model, designed to simulate the first-order trends, such as magnitude-frequency distributions or seasonal patterns, in lahar activity and sediment transport. We use the Belham River Valley, Montserrat, as a case study. This small (~15km<sup>2</sup>) catchment has been repeatedly disturbed by five phases of volcanic activity at the Soufrière Hills Volcano since 1995. The multi-phase nature of this eruption, together with the varying nature and magnitude of disturbances throughout the eruption, has driven a complex disturbance-recovery cycle, which is further compounded by inter-annual climatic variations (e.g. ENSO). Lahars have occurred frequently in response to rainfall in the Belham River Valley, and their occurrence has evolved through the repeated disturbance-recovery cycle. This activity has resulted in significant net valley floor aggradation and widening, consequent burial and destruction of buildings and infrastructure, as well as coastal aggradation of up to ~250m. Within SedCas_Volcano, we account for evolving sediment supply, vegetation cover and rainfall, to simulate the lahar activity and channel change observed in the Belham River Valley since January 2001. Following this, we test the model under different hypothetical eruptive scenarios. [MOU2] Our goal is to assess the efficacy of such models for reproducing patterns of lahar activity and geomorphic change in river systems that are repeatedly disturbed by volcanic activity.</p>

scholarly journals Simulation of Historic Glacier Variations with a Simple Climate-Glacier Model

1988 ◽  
Vol 34 (118) ◽  
pp. 333-341 ◽  
Author(s):  
Johannes Oerlemans
Keyword(s):  
Volcanic Activity ◽  
Climate Model ◽  
Ring Width ◽  
Volcanic Eruptions ◽  
Solar Variability ◽  
Surface Radiation ◽  
Greenhouse Warming ◽  
Radiation Balance ◽  
Equilibrium Line Altitude ◽  
Modelling Studies

AbstractGlacier variations during the last few centuries have shown a marked coherence over the globe. Characteristic features are the maximum stand somewhere in the middle of the nineteenth century, and the steady retreat afterwards (with some minor interruptions depending on the particular region). In many papers, qualitative statements have been made about the causes of these fluctuations. Lower temperatures associated with solar variability and/or volcanic activity are the most popular explanations. In particular, the statistical relation between glacier activity and major volcanic eruptions appears to be strong.In this paper, an attempt is made to simulate recent glacier fluctations with a physics-based model. A simple climate model, calculating perturbations of surface-radiation balance and air temperature (not necessarily in phase!), is coupled to a schematic time-dependent glacier model. The climate model is forced by volcanic activity (Greenland acidity and/or Lamb’s dust-veil index) and greenhouse warming. Solar variability was not considered, because its effect on climate has still not been demonstrated in a convincing way. The output is translated into variations in equilibrium-line altitude, driving the glacier model.The simulated variations in glacier length show good agreement with the observed record, but the amplitude is too small. This is improved when mass-balance gradients are assumed to be larger in warmer climates. Compared to recently published modelling studies of particular glaciers, in which series of local parameters (e.g. tree-ring width and temperature) were used as forcing, the present simulation is better. This suggests that the radiation balance is a decisive factor with regard to glacier variations on longer time-scales. The model experiments lend support to the results of Porter (1986), who concluded from a more qualitative study that a strong relation exists between periods of increased volcanic activity and glacier advances.A comparison of some selected runs shows that, according to the present model, the greenhouse warming would be responsible for about 50% of the glacier retreat observed over the last 100 years.

A continuous 250-year record of volcanic activity from Princess Elizabeth Land, East Antarctica

2002 ◽  
Vol 14 (1) ◽  
pp. 55-60 ◽  
Author(s):  
M.J. Zhang ◽  
Z.Q. Li ◽  
C.D. Xiao ◽  
D.H. Qin ◽  
H.A. Yang ◽  
...  
Keyword(s):  
Volcanic Activity ◽  
Major Ions ◽  
Accumulation Rate ◽  
Ice Core ◽  
Volcanic Eruptions ◽  
East Antarctica ◽  
Mean Annual Temperature ◽  
High Definition ◽  
Concentration Data ◽  
High Accumulation

A 51.85 m ice core collected from site LGB65 (accumulation rate 127 kg m−2 a−1, mean annual temperature −33.1°C) in Princess Elizabeth Land, East Antarctica, during the 1996–97 Chinese First Antarctic Inland Expedition has been analysed for chemical composition and oxygen isotope ratio. Based on the high definition of seasonal variations of major ions, the ice core was dated with errors within ± 3 years. The continuous sulphate analysis of the ice core provides an annually resolved proxy history of southern hemisphere volcanism in the past 250 years. High nssSO42−, concentrations seem to be well correlated to some explosive volcanic eruptions, such as Tambora (AD 1815), Coseguina (AD 1835), Krakatoa (AD 1883) and Tarawera (AD 1886). In comparison with other volcanic records, it seems that nssSO42− concentration data provide a better proxy for detecting volcanic activity than nssSO42− fluxes in low and intermediate accumulation regions, however, in high accumulation regions, small and moderate events may be more identifiable using of nssSO42− flux data.

scholarly journals On the agency of water in volcanic eruptions; with some observations on the thickness of the Earth's crust from a geological point of view; and on the primary cause of volcanic action

1887 ◽  
Vol 41 (246-250) ◽  
pp. 117-173 ◽  
Keyword(s):  
Volcanic Activity ◽  
Volcanic Eruptions ◽  
Point Of View ◽  
Earth’S Crust ◽  
Difference Of Opinion ◽  
Established Fact ◽  
The Subject ◽  
Earth's Crust

The important part played by water in volcanic eruptions is a well recognised and established fact, but there is great difference of opinion among geologists as to whether water should be considered the primary or secondary agent, and as to the mode, time, and place of its intervention. The prevailing opinion in this country is that water is the primary cause of volcanic activity. Whichever view may be adopted, the subject is one which is so largely concerned with the laws regulating the underground circulation of water, that the consideration of the two questions must proceed pari passu .

scholarly journals Sound Waves Help Scientists Track Volcanic Eruptions

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
JoAnna Wendel
Keyword(s):  
Volcanic Activity ◽  
Seismic Waves ◽  
Volcanic Eruptions ◽  
Sound Waves

When sound waves hit the ground, they shake seismometers like earthquake waves. Scientists can now use these sound-induced seismic waves to investigate volcanic activity.

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