Sedimentation Of Volcanic Ash Research Articles

Identification of magnetic minerals in peatland at the section of DD REP B 693 lake Diatas using XRD (X-ray Diffraction)

Volcanic ash is dispersed into the air when an eruption occurs, whilst the magma that reaches the surface of the Earth cools to form igneous rocks before eventually breaking down to form sedimentary rocks. One of the places where the sedimentation of volcanic ash occurs following eruptions are peatlands. This study aims to determine the type of magnetic minerals contained in the peat at Lake Diatas. The identity of the magnetic minerals was determined using the X-Ray Diffraction method. The samples used in this study are taken based on depth of the peat core where a value of magnetic susceptibility had been measured previously. The results of the x-ray diffraction analysis for each sample obtained are the diffraction angle (2θ), distance between fields (dhkl ), diffraction intensity (I) and relative intensity. Data from this measurement are then compared with magnetic mineral data bases in order to identify the identity of the magnetic minerals within the peat. Analysis of the results obtained using X-Ray Diffraction indicate the identity of the magnetic minerals in the peat samples at Lake Diatas. The dominant type of magnetic mineral is magnetite (Fe3O4), along with othermagnetic mineralssuch as hematite. Magnetite diffracts at 18.3773°, 30.9888°, 31.5036°, 53.6169°, 65.7656°, 78.6261°, hematite at 65.9474°, 75.1103°, 78.8619°, while non-magnetic minerals such as quartz diffracts at 28.0575°, 28.2029°, 52.4150°.

Estimating the 3D shape of volcanic ash to better understand sedimentation processes and improve atmospheric dispersion modelling

The sedimentation rate of volcanic ash through the atmosphere influences its travel distance, with important implications for aviation and health. The fall velocity of a particle depends on its size and density, but also shape, and volcanic ash is not spherical. To capture the sedimentation of ash, atmospheric dispersion models use empirical drag equations calibrated using geometric shape descriptors. However, particle shape data are scarce and there is no standard method of shape measurement. In addition, shape measurements are not always available during an eruption, when dispersion models are used operationally to forecast ash hazard. We assess the variability in the shape of volcanic ash from Icelandic eruptions using X-ray computed tomography. To consider how good different drag equations and shape descriptors are at representing the sedimentation of volcanic ash we compare calculated fall velocities to measured fall velocities of volcanic ash in air in a settling column. We then suggest the best drag equations and shape descriptors for use in atmospheric dispersion models. We find that shape-dependent drag equations produce more accurate results than a spherical approximation. However, accurate drag calculations based on the shape descriptor sphericity, which is a function of surface area, require the imaging resolution to be within the range of 102 - 105 voxels per particle (where a voxel is a volumetric pixel) as surface area is sensitive to imaging resolution. We suggest that the large-scale form of the particle impacts sedimentation more than small-scale surface roughness. Shape descriptors based on ratios between principal axis lengths are more practical as they are less variable among particle size classes and much less sensitive to imaging resolution. Finally, we use particle shape data from this study and literature sources to make recommendations on default values for use with atmospheric dispersion models where no shape data are available.

Parameters Governing the Community Structure and Element Turnover in Kermadec Volcanic Ash and Hydrothermal Fluids as Monitored by Inorganic Electron Donor Consumption, Autotrophic CO2 Fixation and 16S Tags of the Transcriptome in Incubation Experiments.

The microbial community composition and its functionality was assessed for hydrothermal fluids and volcanic ash sediments from Haungaroa and hydrothermal fluids from the Brothers volcano in the Kermadec island arc (New Zealand). The Haungaroa volcanic ash sediments were dominated by epsilonproteobacterial Sulfurovum sp. Ratios of electron donor consumption to CO2 fixation from respective sediment incubations indicated that sulfide oxidation appeared to fuel autotrophic CO2 fixation, coinciding with thermodynamic estimates predicting sulfide oxidation as the major energy source in the environment. Transcript analyses with the sulfide-supplemented sediment slurries demonstrated that Sulfurovum prevailed in the experiments as well. Hence, our sediment incubations appeared to simulate environmental conditions well suggesting that sulfide oxidation catalyzed by Sulfurovum members drive biomass synthesis in the volcanic ash sediments. For the Haungaroa fluids no inorganic electron donor and responsible microorganisms could be identified that clearly stimulated autotrophic CO2 fixation. In the Brothers hydrothermal fluids Sulfurimonas (49%) and Hydrogenovibrio/Thiomicrospira (15%) species prevailed. Respective fluid incubations exhibited highest autotrophic CO2 fixation if supplemented with iron(II) or hydrogen. Likewise catabolic energy calculations predicted primarily iron(II) but also hydrogen oxidation as major energy sources in the natural fluids. According to transcript analyses with material from the incubation experiments Thiomicrospira/Hydrogenovibrio species dominated, outcompeting Sulfurimonas. Given that experimental conditions likely only simulated environmental conditions that cause Thiomicrospira/Hydrogenovibrio but not Sulfurimonas to thrive, it remains unclear which environmental parameters determine Sulfurimonas’ dominance in the Brothers natural hydrothermal fluids.

An adaptive semi-Lagrangian advection model for transport of volcanic emissions in the atmosphere

Abstract. The dispersion of volcanic emissions in the Earth atmosphere is of interest for climate research, air traffic control and human wellbeing. Current volcanic emission dispersion models rely on fixed-grid structures that often are not able to resolve the fine filamented structure of volcanic emissions being transported in the atmosphere. Here we extend an existing adaptive semi-Lagrangian advection model for volcanic emissions including the sedimentation of volcanic ash. The advection of volcanic emissions is driven by a precalculated wind field. For evaluation of the model, the explosive eruption of Mount Pinatubo in June 1991 is chosen, which was one of the largest eruptions in the 20th century. We compare our simulations of the climactic eruption on 15 June 1991 to satellite data of the Pinatubo ash cloud and evaluate different sets of input parameters. We could reproduce the general advection of the Pinatubo ash cloud and, owing to the adaptive mesh, simulations could be performed at a high local resolution while minimizing computational cost. Differences to the observed ash cloud are attributed to uncertainties in the input parameters and the course of Typhoon Yunya, which is probably not completely resolved in the wind data used to drive the model. The best results were achieved for simulations with multiple ash particle sizes.

The joy of transient chaos.

We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

Mioceńskie poziomy tufitowe z otworów wiertniczych Busko (Młyny) PIG-1 i Kazimierza Wielka (Donosy) PIG-1

MIOCENE TUFFITE LEVELS FROM THE BUSKO (MŁYNY) PIG-1 AND KAZIMIERZA WIELKA (DONOSY) PIG-1 BOREHOLES Abstract. The paper presents detailed description of the tuffite levels from the Busko (Mlyny) PIG-1 and Kazimierza Wielka (Donosy) PIG-1 boreholes (Miocene, Carpathian Foredeep). Mineral and petrographic composition of the tuffites was examined with a polarizing microscope and a scanning electron microscope (SEM-EDS). Chemical composition of whole rock samples was determined with the ICP and INAA methods. Research has shown that the tuffite levels differ in terms of the chemical composition of glass, alkaline plagioclase content, grain size of the components and content of typical rock-forming minerals (e.g. biotite, pyroclastic quartz and potassium feldspar). Normal gradations and lamination of the tuffites indicate that they originated as a result of sedimentation of volcanic ash in marine conditions. Degree of preservation of pyroclastic minerals in the tuffites reflects changes in the geochemical environment of deposition. The first tuffite level above the evaporites, the most widespread and with characteristic chemical composition of pyroclastic components, can be applied in the correlation of deposits in the Carpathian Foredeep.

Major, trace and platinum-group element geochemistry of the Upper Triassic nonmarine hot shales in the Ordos basin, Central China

The Upper Triassic Chang 7 non-marine hot shales have been proven to contribute to Mesozoic oil reservoirs in the Ordos basin, Central China. These shales have been studied extensively in sedimentology, petrology and organic geochemistry. However, the factors controlling the development of the shales are still ambiguously constrained. This paper presents the major, trace, and platinum-group elements (PGEs) data to address these issues. The Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), C-values and clay mineral compositions indicate that the Chang 7 hot shales were developed in a humid paleoclimate. The indicators of redox conditions (Eu/Eu∗, Ce/Ce∗, Ceanom, δU, U/Th, V/(V+Ni) and V/Cr) suggest that the Chang 7 hot shales were developed under anoxic environment. Uranium enrichment (average 46.10ppm) is an important distinguished signature of the Chang 7 hot shales, which was mainly related to synchronous volcanic ash sediments and/or possibly hydrothermal fluids. The PGE concentrations of the Chang 7 hot shales were reported for the first time here, and can be subdivided into two groups. The total abundances of the Group One samples are relatively lower and derived mainly from detrital minerals, while the Group Two samples are relatively higher, and are also likely linked to the synchronous volcanic ash sediments and/or possibly hydrothermal fluids. Combined with the regional geological setting, we tentatively propose that the tectonics is the major control on the development of the Chang 7 hot shales.

완도 송곡지구 화산암류 비탈면의 현장조사 및 안정성 검토 사례 연구

화산활동은 용암의 분출과 화산재의 퇴적 작용이 복합적으로 발생함에 따라 지질학적으로 매우 복잡한 화산암복합체를 형성하는 경우가 많다. 화산암류 암석들로 구성된 송곡 지구는 단층을 중심으로 한 여러 불연속면의 조합으로 비탈면 하단부에서 붕괴가 발생하였다. 붕괴부를 중심으로 한 평사투영 해석 결과 모든 형태의 붕괴 가능성이 인지되었으며, 개별요소법(DEM)을 이용한 불연속면 거동 특성 분석 결과, 전체변위 207 mm, 절리 최대전단 변위 114 mm로 나타났으며, 소성 영역 발생 구간은 붕괴부의 단층면에서 확인되었다. 화산암류 비탈면은 암종간의 차별 풍화, 암석의 높은 투수성에 기인한 지하수 영향, 냉각 수축에 의한 체계적 절리 발달로 인해 공학적으로 취약한 특성을 보인다. 화산암류 비탈면의 안정화 대책 고려시, 상세 지질조사를 통한 구성암석의 지질학적 특성, 불연속면과 이완암블록의 변화량 분포 등의 자료가 활용되어야 할 것이다. Volcanic activity commonly creates a highly complicated volcanic complex due to the admixture of lava flow and sedimentation of volcanic ash. The Song-Gok site is composed of volcanic rocks that collapsed at the lower part of the slope, in combination with several discontinuities in and around a fault. The results of projection analysis indicated the possibility of plane, wedge, and toppling failure in the failure section. The results of discontinuity modeling using the Distinct Element Method (DEM) revealed a total displacement of 207 mm and a joint shear displacement of 114 mm. The yield surface zone was verified at the fault plane of the failure section. In geotechnical terms, volcanic rock slopes are characteristically vulnerable to failure because of differential weathering among the various rock types, the effect of groundwater based on the permeability of the rocks, and the presence of systematic joints generated by the cooling and contraction of lava. When considering the stability of a volcanic rock slope, it is necessary to consider data such as the geological features of the rock, as obtained through detailed geological survey, and variations in discontinuities and rock blocks.

The effect of Etna volcanic ash clouds on the Maltese Islands

In this paper, we have studied in depth the effect of Etna volcanic ash clouds on the Maltese Islands. Research was carried out to gather information about Etna's eruptions that impacted the Maltese Islands, starting with historical eruptions dating back to the 14th century continuing to present day. A statistical approach was utilized to provide tephra deposit load and ash concentration using PUFF — a model which simulates the transport, dispersion and sedimentation of volcanic ash. Three different eruptive scenarios that characterize Etna's recent activity were considered; the first scenario representing the 2001 eruption (Sc1), the second scenario representing the July 1998 eruption (Sc2) whilst the third scenario represents the recent activity in 2011–2012 (Sc3). We found that the time taken for the volcanic ash cloud to reach the Maltese Islands, when the wind direction is toward the south-west ranges from 4 to 6h. The probability that an Etna volcanic cloud reaches Malta during an eruption is about 15% per annum. The now calibrated model may be now used to produce deposit load and cumulative columnar load (i.e. summation from maximum height of volcanic cloud to ground) of volcanic ash in atmosphere for the Maltese area and help the aviation authorities and Malta airport to make decisions during Etna eruptions. This will be of direct use to local communities and aviation.

Influence of volcanic ash sediments on spore adhesion of the red alga Gelidium elegans from the coastal seabed around Miyakejima Island, Japan

The populations of red alga Gelidium elegans along the coast of Miyakejima Island were severely damaged by a volcanic eruption in 2000. The effect of this volcanic eruption has been long lasting, and populations of this red alga still have not recovered. We investigated the effect of seabed sediment particles derived from volcanic ash on the substrate adhesion of G. elegans spores. The analysis provides evidence that increasing amounts of sediment particles result in lower adhesion rates of G. elegans spores, and that smaller sediment particles have a greater influence on adhesion. The amount of seabed sediment particles around Miyakejima Island was 9.3–1815.4 mg/cm2. This amount has changed greatly from year to year. The adhesion rate of G. elegans spores in water around Miyakejima Island was 0 % at all points in 2008 and 2010, but it was estimated as 6.3–38.6 % in 2009. These results suggest that there is significant inhibition of algal spore adhesion by seabed sediment particles derived from volcanic ash around Miyakejima Island.

A model for wet aggregation of ash particles in volcanic plumes and clouds: 2. Model application

The occurrence of particle aggregation has a dramatic effect on the transport and sedimentation of volcanic ash. The aggregation process is complex and can occur under different conditions and in multiple regions of the plume and in the ash cloud. In the companion paper, Costa et al. develop an aggregation model based on a fractal relationship to describe the rate particles are incorporated into ash aggregates. The model includes the effects of both magmatic and atmospheric water present in the volcanic cloud and demonstrates that the rate of aggregation depends on the characteristics of the initial particle size distribution. The aggregation model includes two parameters, the fractal exponent Df, which describes the efficiency of the aggregation process, and the aggregate settling velocity correction factor ψe, which influences the distance at which distal mass deposition maxima form. Both parameters are adjusted using features of the observed deposits. Here this aggregation model is implemented in the FALL3D volcanic ash transport model and applied to the 18 May 1980 Mount St. Helens and the 17–18 September 1992 Crater Peak eruptions. For both eruptions, the optimized values for Df (2.96–3.00) and ψe (0.27–0.33) indicate that the ash aggregates had a bulk density of 700–800 kg m−3. The model provides a higher degree of agreement than previous fully empirical aggregation models and successfully reproduces the depositional characteristics of the deposits investigated over a large range of scales, including the position and thickness of the secondary maxima.

A new genus and species of cockroach (Blattida: Phyloblattidae) from the Permian/Triassic boundary beds of Tunguska Basin in eastern Siberia, Russia

Macroscopic fossils of terrestrial animals originating directly from deposits close to the Permian/Triassic boundary are very scarce. Volcanic ash sediments in Eastern Siberia were found to hold the cockroach Sobytie tungusicum gen. et sp. n. This new taxon belongs to the predominantly Palaeozoic family Phyloblattidae, but has many advanced features characteristic of the Mesozoic family Caloblattinidae, and also of the basal Liberiblattinidae. These connections provide an indication of the origin of the family Liberiblattinidae and thus all the Mesozoic cockroach lineages from such Phyloblattidae – precursors of the Caloblattinidae.