Volcanic ash

This work finds a way in which lateritic soil within Ota, Ogun State of Nigeria could be used in the production of hollow sandcrete blocks. This replacement is intended to develop more economic sandcrete blocks since the cost of lateritic soil in Ota is much less than the cost of the conventional fine aggregate used in the production of sandcrete blocks without compromising the intergrity of the blocks. It was deduced from literatures that inclusion of lateritic soil in sandcrete block production results in a lesser quality blocks. However, this work found the maximum permissible replacement that still makes the blocks to be within the recommended standard. The blocks were produced with each lateritic soil sample from different sources replacing sand in steps of ten percent to 60% and their compressive strengths determined and compared with that of a standard sandcrete block to check for the acceptable percentage replacement. In the compressive strength test, 72 numbers of 225 x 225 x 450mm hollow laterised sandcrete block sizes were produced, cured and crushed to determine their twenty-eight-day compressive strength. Cost analysis was performed discovered that the inclusion of the lateritic soil saves the cost of production by 11.89%. This percentage replacement can be recommended to the block moulding industries within Ota with a view to reducing the production costs of the blocks.

This paper investigates the influence of volcanic ash (VA) and vinyl acetate/ethylene copolymer powder (PVA/VE) as partial cement replacement on the engineering properties of blended binders concretes. The parameters studied included density, workability and compressive strength. A total number of 12 trial mixtures were prepared and tested by varying the proportions of binders. Firstly, VA was used to replace OPC at dosage levels of 5%, 10%, 15%, 20%, 25%, and 50% by weight of the binder. Secondly, PVA/VE was used to replace OPC at dosage levels of 0.5%, 1%, 1.5%, 2% and 2.50% by weight of the binder. Finally, the optimum replacement levels of VA and PVA/VE were determined and used to prepare a new trial mix. The results show that cement replacement up to 15% volcanic ash and 1.5% PVE/VE leads to increase in workability and compressive strength for C30 grade compared with the control mixture.

The Quaternary Zarloukh Bentonite -Tuff (ZBT) deposit occurs within the Hemrin South Mountain, northern Iraq. The ZBT deposit occurs as depression-filling exposed on the erosional surface of the siliciclastic Pliocene Muqdadiya Formation and covered by an overburden of recent sediments. The thickness of the studied industrial bentonite bed is ~80-100 cm, occurring at the bottom of these depressions, covered by ~3-4 m thick bedded volcanic tuff, which also contains many 10-12 cm thick bentonite layers along its bedding planes. The volcanic ash at the bottom of lakes/swamps with shallow water content acted as basins for the deposition of falling volcanic ash, which immersed in water and devitrified to bentonite at a later stage by hydration and chemical interactions, meanwhile the continued fallen ash consolidated as tuff beds protecting the bentonite formed at the bottom of the depressions. The bentonite bed shows mini-scale trough crossbedding as a sign for its formation within a low energy, shallow agitated water in lakes/swamps. The bentonite and its precursor tuff show some differences in the concentration of Ca, Mg, Na, and K representing the exchangeable elements in smectite (montmorillonite), which is the predominant clay mineral in bentonite because of the probable gain of bentonite for these elements during the process of bentonitization of volcanic ash, which also formed the tuff. The ZBT has most probably the same origin as the Hemrin Basalt located NW of ZBT deposit. The chondrite-normalized REEs distribution pattern of ZBT and the Hemrin Basalt is similar, both showing enrichment and negative slope for the LREEs relative to the flat-lying HREEs. The Th vs. Co and the Th/ Yb vs. Ta/Yb diagrams indicated that the ZBT and the Hemrin Basalt fall within the field of high-K calc-alkaline basalt and shoshonite and the andesitic basalt-andesite rocks reflecting their common origin.

This paper presents the first well-dated palaeoenvironmental study from the Sarliève marsh, a unique sedimentary record in the Limagne plain of central France, where all previous studies suffered from unreliable chronologies. We developed an accurate radiocarbon-based agedepth model and performed high-resolution multi-proxy sedimentological and geochemical analysis on a new sediment core from the heart of the sedimentary basin, improving the chronology and Holocene palaeoenvironmental interpretations. We found six potential (crypto)tephra fallouts (c. 9750, 8500, 7500, 7400, 6300, and 5800 cal yr BP) that enrich the Holocene tephrostratigraphy in Limagne, five of which were not previously documented in the sediments of the marsh. We also detected, for the first time, an array of volcanic phenomena such as degassing episodes (c. 6950 and 6050 cal yr BP), ash leaching phases (10250-9750, 8500-7400, and 5800-5100 cal yr BP), and P r e p r i n t earthquakes (c. 6800, 6600, 6050, 6100, and 1600 cal yr BP), suggesting a hitherto unsuspected period of high volcanic activity in the area between 7500 and 5800 cal yr BP. This increased activity appears to have caused a massive forcing of hydrosedimentary dynamics in the catchment in the Middle Holocene, by supplying significant volumes of fine volcanic ash to the palustrine basin, and thereby questioning the current Holocene morpho-sedimentary narrative for Limagne. The basin became a permanent freshwater lake after the Mid-Holocene climatic shift, and detrital influxes likely due to anthropogenic soil erosion appeared c. 5500 cal yr BP and grew steadily after 5000 cal yr BP, with a marked lull between 3600 and 3000 cal yr BP, perhaps because of a phase of settlement abandonments during the middle and early-late Bronze age. A series of lacustrine low-stands (c. 4750-4600, 3750-3600, 3350-3200 and 2950-2800 cal yr BP) that correlate strongly with western alpine lake records do not seem to have caused significant changes in the anthropogenic impact on soils modifying the sedimentary supply. Our results suggest that this lake could have been artificially drained c. 2550 cal yr BP, several centuries earlier than previously estimated, allowing us to hypothesize that Early Iron age societies already had substantial capacity to modify the hydraulic environment. Hydromorphic conditions developed thereafter, including complex short-lived marshy phases in late Roman times.

The present study discusses lithology and diagenetic characteristics of the siliciclastic Cambrian and the enclosing Ediacaran and Ordovician deposits in the northern Baltic Sedimentary Basin (BSB). The Neoproterozoic and Lower Palaeozoic sediments are despite their age unconsolidated with primary porosity of 20–25% for both shales and sandstones. The sparse Fe-dolomite cementation of arenitic and subarenitic sandstones and siltstones occurs mainly at lithological contacts with the massive Ediacaran and Lower Cambrian claystones and is probably related to ions released during illitization. In contrast to weakmechanical and chemical compaction of sandstone, the clay mineral diagenesis of Cambrian deposits is well advanced. The highly illitic (80–90%) nature of illite-smectite (I-S) suggests evolved diagenetic grade of sediments which conflicts with shallow maximum burial and low compaction. Smectite-to-illite transformation has resulted in formation of diagenetic Fe-rich chlorite in ...

Selama erupsi Gunung Merapi pada tanggal 26 Oktober 2010 hingga 9 Desember 2010 material vulkanik yang dikeluarkan mencapai 140 juta m3, abu vulkanik sebagai salah satu material yang melimpah belum termanfaatkan maksimal, padahal sifat pozzolanic pada abu vulkanik memungkinkannya sebagai bahan subtitusi sebagian semen pada campuran beton. Untuk itu perlu dilakukan penelitian Kuat Tekan Beton dengan menggunakan bahan Abu Vulkanik sebagai pengganti sebagian semen. Target mutu perencanaan beton K-220 dengan pengujian kuat tekan beton dilakukan pada umur 14 hari dengan masing-masing perlakuan dibuat 3 buah benda uji dengan variasi kadar abu vulkanik Gunung Merapi 0%, 10%, 20%, 30% dan 40% dari berat semen. Penambahan abu vulkanik sampai dengan 30% pada beton uji dapat mencapai kuat tekan sebesar 21,21 Mpa, sehingga terjadi peningkatan kuat tekan sebesar 7,16% dari beton kontrol. Selanjutnya pada penambahan abu vulkanik sebesar 40% pada beton uji, kuat tekan mulai menurun yaitu mengalami regresi sebesar 8,58% dibandingkan dengan beton kontrol. Berdasarkan analisis, maka ada batasan yang memungkinkan kombinasi antara abu vulkanik dan semen efektif dijadikan bahan ikat, akan tetapi ada batasan jumlah dari abu vulkanik yang tidak lagi efektif sebagai bahan ikat lagi. Selama erupsi Gunung Merapi pada tanggal 26 Oktober 2010 hingga 9 Desember 2010, material vulkanik yang dikeluarkan mencapai 140 juta m3, Kabupaten Magelang dan Boyolali merupakan daerah yang banyak terkena awan panas sedangkan daerah Sleman lebih karena lahar panas. Timbunan abu vulkanik di Desa Glagaharjo, Kecamatan Cangkringan, Sleman, Daerah Istimewa Yogyakarta mencapai ketinggian 30 meter 1 . Abu vulkanik yang melimpah belum termanfaatkan 1 "Pasir dan Abu Vulkanik Bernilai Ekonomi" Kompas, 8 November 2010, hal 3.

The paper presents elements of research conducted in the Faculty of Civil Engineering and Geodesy of the Military University of Technology, Warsaw, Poland, concerning application of mesoscale models and remote sensing data to determining meteorological conditions of aircraft flight directly related with atmospheric instabilities. The quality of meteorological support of aviation depends on prompt and effective forecasting of weather conditions

Bombay hills east of SH1 in late summer (23 March 2007)  irrigators were operating in some fields. Photo: David Lowe Potatoes growing in Pukekohe soils on gently sloping shoulder of Pukekohe Hill, 10 October, 2008. View towards southwest where the hills (some basaltic) are bounded by Waikato Fault. Waikato River flows in valley with its mouth at top right (Port Waikato

Thermodynamic stability diagrams based on a topological procedure constrained by thermodynamic data for idealised smectites and imogolite indicate that imogolite is the favoured alteration product of rhyolitic volcanic glass in both the soil and nearshore marine environments. However, smectites are observed in young nearshore marine sediments, suggesting a rapid alteration. The rate of formation of clay minerals has been previously demonstrated to be a function of their equilibrium constant (K) and the reaction activity quotient (Q) -effectively the divergence from equilibrium. Extending this treatment to include the process of glass dissolution (8) as a prelude to clay mineral formation ($), the rate of clay mineral formation is demonstrated to be a function of the parameter: Where k+ and k' + are the rate constants of dissolution for glass and clay respectively. The values of Q91Ke are such that in general, the rate determining step is determined by Qq.JK~ Based on this approach, the rate of formation of smectite is fast in silica saturated interstitial waters in the nearshore marine environment, perhaps a thousand times faster than the formation of imogolite or halloysite in soil waters.

During explosive eruptions, volcanic plumes inject ash into the atmosphere and may severely affect air traffic, as illustrated by the 2010 Eyjafjallajökull eruption. Quantitative estimates of ash injection can be deduced from the height reached by the volcanic plume on the basis of scaling laws inferred from models of powerful Plinian plumes. In less explosive basaltic eruptions, there is a partitioning of the magma influx between the atmospheric plume and an effusive lava flow on the ground. We link the height reached by the volcanic plume with the rate of ash injection in the atmosphere via a refined plume model that (1) includes a recently developed variable entrainment law and (2) accounts for mass partitioning between ground flow and plume. We compute the time evolution of the rate of injection of ash into the atmosphere for the Eyjafjallajökull eruption on the basis of satellite thermal images and plume heights and use the dispersion model of the Volcanic Ash Advisory Center of Toulouse to translate these numbers into hazard maps. The classical Plinian model would have overestimated ash injection by about 20% relative to the refined estimate, which does not jeopardize risk assessment. This small error was linked to effective fragmentation by intense interactions of magma with water derived from melting of ice and hence strong mass partitioning into the plume. For a less well fragmented basaltic dry eruption, the error may reach 1 order of magnitude and hence undermine the prediction of ash dispersion, which demonstrates the need to monitor both plume heights and ground flows during an explosive eruption.

Le tuf FJ-1 de Fejej (sud-Omo, Éthiopie) Nouvelles corrélations téphrostratigraphiques sur la base de la géochimie avec les formations plio-pléistocènes du bassin de l'Omo-Turkana Fejej FJ-1 tuff (south-Omo, Ethiopia): new tephrostratigraphical correlations based on geochemical compositions with the plio-pleistocene formations from the Omo-Turkana basin

Forecasting volcanic ash atmospheric pathways is of utmost importance for aviation. Volcanic ash can interfere with aircraft navigational instruments and can damage engine parts. Early warning systems, activated after volcanic eruptions can alleviate the impacts on aviation by providing forecasts of the volcanic ash plume dispersion. The quality of these short-term forecasts is subject to the accuracy of the meteorological wind fields used for the initialization of regional models. Here, we use wind profiling data from the first high spectral resolution lidar in space, Aeolus, to examine the impact of measured wind fields on regional NWP and subsequent volcanic ash dispersion forecasts, focusing on the case of Etna’s eruption on March 2021. The results from this case study demonstrate a significant improvement of the volcanic ash simulation when using Aeolus-assimilated meteorological fields, with differences in wind speed reaching up to 8 m/s when compared to the control run. When ...

Forecasting volcanic ash atmospheric pathways is of utmost importance for aviation. Volcanic ash can interfere with aircraft navigational instruments and can damage engine parts. Early warning systems, activated after volcanic eruptions can alleviate the impacts on aviation by providing forecasts of the volcanic ash plume dispersion. The quality of these short-term forecasts is subject to the accuracy of the meteorological wind fields used for the initialization of regional models. Here, we use wind profiling data from the first High Spectral Resolution Lidar in Space, Aeolus, to examine the impact of measured wind fields on regional NWP and subsequent volcanic ash dispersion forecasts, focusing on the case of Etna’s eruption on March 2021. The results from this case study demonstrate a significant improvement of the volcanic ash simulation when using Aeolus-assimilated meteorological fields, with differences in wind speed reaching up to 8 m/s when compared to the control run. When ...

Volcanic eruptions can emit large amounts of ash into the atmosphere, which can have significant impacts on infrastructure, human health, agriculture and air traffic. Remote sensing instruments can efficiently detect airborne ash plumes, and the measured spectra can be exploited to obtain information on the physical characteristics of ash (grain size distribution, concentration, optical depth). The key parameter on which all such satellite retrievals depend is the complex refractive index (CRI) which remains one of the largest sources of uncertainty in the retrieval process. Here we present a complementary dataset of refractive indices of volcanic ash to that published by , to cover a part of the major explosive eruptions occurred during the past 50 years. These CRIs were obtained using an innovative experimental methodology which consists in measuring simultaneously the extinction spectra in the IR and UV/visible domain and the size distribution of ash in suspension in a nitrogen flow. These experimental data are the main input to the retrieval process of CRI. The numerical routine uses Mie theory coupled with Kramers-Kronig relationship to retrieve the imaginary and the real part of the complex refractive index. This methodology has been successfully applied on samples collected from various eruptions and deposits in Indonesia (Kelud), Chile (Chaitén), Italy (Stromboli), Russia (Karymsky), Tanzania (Rungwe, Mount Meru), Ethiopia (Corbetti), Philippines (Taal, Pinatubo) and USA (Mount St. Helens). Significant variations of the real and imaginary part of the CRI are observed according to the chemical composition of the samples. Moreover, the sensitivity of the CRI to chemical composition and mineralogical structure (amorphous/crystalline fraction) has been investigated and shows a strong dependence of the CRI on these parameters.

The complex refractive indices of eight volcanic ash samples, chosen to have a representative range of SiO2 contents, were retrieved from simultaneous measurements of their spectral mass extinction coefficient and size distribution. The mass extinction coefficients, at 0.33–19 μm, were measured using two optical systems: a Fourier transform spectrometer in the infrared and two diffraction grating spectrometers covering visible and ultraviolet wavelengths. The particle size distribution was measured using a scanning mobility particle sizer and an optical particle counter; values for the effective radius of ash particles measured in this study varied from 0.574 to 1.16 μm. Verification retrievals on high‐purity silica aerosol demonstrated that the Rayleigh continuous distribution of ellipsoids (CDEs) scattering model significantly outperformed Mie theory in retrieving the complex refractive index, when compared to literature values. Assuming the silica particles provided a good analog...

The classical section described by Darwin at the mouth of the Río Santa Cruz was a landmark in the later stratigraphy of the marine Cenozoic of Patagonia. Sedimentological and paleontological studies of rocks from the Monte León Formation at the Darwin and Mount Entrance sections -mouth of the Río Santa Cruz -suggest that they were deposited in an early Miocene inner shelf to subtidal -or even intertidal at the top -environment. The base of the sections is covered and the top is unconformably overlain by Quaternary deposits. The invertebrate fauna (mainly mollusks) mentioned herein -the earliest of which were collected by Darwin and described by Sowerby -were collected from the two sections with a detailed stratigraphic control. It includes brachiopods, echinoderms, scaphopods, bivalves, and gastropods. The similarity of this fauna with that one from the sections at Restinga Norte, Cabeza de León, Las Cuevas, Yegua Quemada and Monte Observación, all south of the study area, allow correlation with them. In addition to the equivalence of the faunas, sedimentological features at all these localities are also the same. Therefore, all the shell beds involved should be referred to the Punta Entrada Member of the Monte León Formation. The Monte Observación Member should be restricted to its original use and included as a member at the base of the overlying Santa Cruz Formation, outcrops at Cerro Monte León and Cerro Observación.

In June 2019, the Raikoke volcano, Kuril Islands, emitted 0.4-1.8 x 10 9 kg of very fine ash and 1-2 x 10 9 kg of SO 2 up to 14 km into the atmosphere. The eruption was characterized by several phases or puffs of different duration and eruption heights. Resolving such complex eruption dynamics is required for precise volcanic plume dispersion forecasts. To address this issue, we coupled the atmospheric model system ICON-ART (ICOsahedral Nonhydrostatic -Aerosols and Reactive Trace gases) with the 1-D plume model FPlume to calculate the eruption source parameters (ESPs) online. The main inputs are the plume heights for the different eruption phases that are geometrically derived from satellite data. An empirical relationship is used to derive the amount of very fine ash (particles <32µm), which is relevant for long range transport in the atmosphere. On the first day after the onset of the eruption, the modeled ash loading agrees very well with the ash loading estimated from AHI (Advanced Himawari Imager) observations due to the resolution of the eruption phases and the online treatment of the ESPs. In later hours, aerosol dynamical processes (nucleation, condensation, coagulation) explain the loss of ash in the atmosphere in agreement with the observations. However, a direct comparison is partly hampered by water and ice clouds overlapping the ash cloud in the observations. We compared 6-hourly means of model and AHI data with respect to the structure, amplitude, and location (SAL-method) to further validate the simulated dispersion of SO 2 and ash. In the beginning, the structure and amplitude values differed largely because the dense ash cloud leads to an underestimation of the SO 2 amount in the satellite data. On the second and third day, the SAL values are close to zero for all parameters indicating a very good agreement of model and observations. Furthermore, we found a separation of the ash and SO 2 plume after one day due to particle sedimentation, chemistry, and aerosol-radiation interaction. The results confirm that coupling the atmospheric model system and plume model enables detailed treatment of the plume dynamics (phases and ESPs) and leads to significant improvement of the ash and SO 2 dispersion forecast. This approach can benefit the operational forecast of ash and SO 2 especially in case of complex and non-continuous volcanic eruptions like the Raikoke 2019.

The UK Met Office, in its role as one of nine Volcanic Ash Advisory Centres (VAACs) around the world, is responsible for advising international aviation authorities in all impacted countries of the location and movement of clouds of volcanic ash which originate from the ...

The paper presents a multi-model study of a short period of the Eyjafjallajokull eruption in May 2010. As such it is a very limited study, but it highlights some useful challenges with using and comparing a multi-model ensemble for probabilistic volcanic ash forecasting. Some further details on the source terms used would be helpful for the reader to understand the differences between the model outputs. The authors apply the Fractions Skill Score as their measure of model skill, but I have some serious concerns about the way it has been applied here. The WRF-CHEM a priori simulation is clearly much worse than the other models, but this is really not reflected in the FSS. I believe the application of the pixel filtering is biasing the FSS results to suggest the models are performing better than they are. The use of the 99 th percentile is also not mathematically justified. With some revisions to the statistics and data displayed, this would be a more balanced and hence interesting paper for the community.

High quality volcanic ash forecasts are crucial to minimize the economic impact of volcanic hazards on air traffic. Decisionmaking is usually based on numerical dispersion modeling with only one model realization. Given the inherent uncertainty of such approach, a multi-model multi-source term ensemble has been designed and evaluated for the Eyjafjallajökull eruption in May 2010. Its use for air traffic management is discussed. Two multi-model ensembles were built: the first is based on the output of four dispersion models and their own implementation of ash ejection. All a priori model source terms were constrained by observational evidence of the volcanic ash cloud top as a function of time. The second ensemble is based on the same four dispersion models, which were run with three additional source terms: (i) a source term obtained with background modeling constrained with satellite data (a posteriori source term), (ii) its lower bound estimate, and (iii) its upper bound estimate. The a priori ensemble gives valuable information about the probability of ash dispersion during the early phase of the eruption, when observational evidence is limited. However, its evaluation with observational data reveals lower quality compared to the second ensemble. While the second ensemble ash column load and ash horizontal location compare well to satellite observations, 3D ash concentrations are negatively biased. This might be caused by the vertical distribution of ash, which is too much diluted in all model runs, probably due to defaults in the a posteriori source term and vertical transport and/or diffusion processes in all models. Relevant products for the air traffic management are horizontal maps of ash concentration quantiles (median, 75 %, 99 %) at a fine-resolved flight level grid. These maps can be used for route optimization in the areas where ash does not pose a direct and urgent threat to aviation. Cost-optimized consideration of such hazards will result in much less impact on flight cancellations, reroutings, and traffic flow congestions.

This study aims to determine the response of growth and production as well as the availability of silica to the application of chicken manure and volcanic ash in shallot plants (Allium ascalonicum l.). This study used a Randomized Group Design (RAK) with 2 factors. The first factor is chicken manure consisting of 4 levels, namely: A0 = Control (No chicken manure), A1 = 3.75 kg/plot (10 tons/ha), A2 = 7.5 kg/plot (20 tons/ha), A3 = 11.25 kg/plot (30 tons/ha). The second factor is volcanic ash consisting of 4 levels, namely: V0 = Control (No volcanic ash), V1 = 1.9 kg/plot (5 tons/ha), V2 = 3.8 kg/plot (10 tons/ha), V3 = 5.6 kg/plot (15 tons/ha). The results showed that chicken manure up to a dose of 11.25 kg/plot had a significant effect on leaf length, plant wet weight/sample, plant wet weight/plot, plant dry weight/sample, plant dry weight/plot, base saturation, Corganic, pH H2O, but had no significant effect on the number of tubers, CEC and Si availability in paddy fields. Volcanic ash dose treatment had no significant effect on all parameters observed. The interaction between the doses of chicken manure and volcanic ash had no significant effect on leaf length at 2, 3, and 5 weeks of planting, wet weight of plants/sample, dry weight of plants/sample, base saturation, C-organic, pH H2O, number of tubers, CEC and availability of Si in the paddy field, but had a significant effect on leaf length at 4 weeks of planting with the best combination that produced the highest average leaf length, namely treatment A2V3 (7.5 kg/plot of chicken manure and 5.62 kg/plot of volcanic ash): 5.62 kg/plot of volcanic ash), and significantly affected the wet weight of plants/plot and dry weight of plants/plot with the best combination that produced the heaviest average weight, namely treatment A1V2 (3.75 kg/plot of chicken manure : 3.75 kg/plot of volcanic ash).

Portland cement remains the most common type generally in use throughout the world as a basic ingredient of concrete. Five brands of Portland cement commonly available in Nigeria were investigated through series of tests conducted to determine their strength characteristics, setting time, soundness, workability and fineness among others and examined if they meet the minimum standard as stipulated by the British Standard Institute. Five brands of cement considered were Dangote, Elephant, Burham, Diamond and Purechem. The results show that all the brands examined meet the British Standard requirements on all the tests subjected to. Burham cement was fastest with initial setting time of 100 minutes ahead of other, while Dangote cement was the least with initial setting time of 180 minutes. The strengths characteristics of the five brands are similar with slight difference recorded. Dangote cement had the highest strength at 28 th day curing period of 474 KN as the crushing load while the least strength was of Purechem at 370.6 KN as the crushing load.

Portland cement remains the most common type generally in use throughout the world as a basic ingredient of concrete. Five brands of Portland cement commonly available in Nigeria were investigated through series of tests conducted to determine their strength characteristics, setting time, soundness, workability and fineness among others and examined if they meet the minimum standard as stipulated by the British Standard Institute. Five brands of cement considered were Dangote, Elephant, Burham, Diamond and Purechem. The results show that all the brands examined meet the British Standard requirements on all the tests subjected to. Burham cement was fastest with initial setting time of 100 minutes ahead of other, while Dangote cement was the least with initial setting time of 180 minutes. The strengths characteristics of the five brands are similar with slight difference recorded. Dangote cement had the highest strength at 28 th day curing period of 474 KN as the crushing load while the least strength was of Purechem at 370.6 KN as the crushing load.

LITA develops and field tests a long-range automated rover and a science payload to search for microbial life in the Atacama. The Atacama&#x27;s evolution provides a unique training ground for designing and testing exploration strategies and life detection methods for the search for life on Mars.

The 2010 eruption of Eyjafjallajökull (Iceland) and the 2011 eruptions of Grimsvötn (Iceland), Cordon Caulle (Chile) and Nabro (Ethiopia) have drastically heightened the level of awareness in the general population of how volcanic activity can affect everyday life by disrupting air travel. The ingestion of airborne volcanic matter into jet turbines may cause harm by (1) abrasion of engine parts, (2) destabilisation of the fuel/air mix and its dynamics and (3) by melting and sintering ash onto engine parts. To investigate the behaviour of volcanic ash upon reheating, we have performed experiments at ten temperature steps between 700 and 1600°C on (1) fresh volcanic ash from the final explosive phase of the 2010 Eyjafjallajökull (EYJA) eruption and (2) two standard materials used in ingestion tests in the history of turbine testing (MIL E 5007C test sand, MIL; Arizona Test Dust, ATD). We confirm expected large differences in the samples' response to thermal treatment. We quantify the physical basis for these differences using thermogravimetry and differential scanning calorimetry. Glassy volcanic ash softens at temperatures that are considerably lower than those required for crystalline silicates to start to melt. We find that volcanic ash starts softening at temperatures as low as 600°C and that complete sintering takes place at temperatures as low as 1050°C. Accordingly, the ingestion of volcanic ash in the hot zone of turbines will rather efficiently transform the angular volcanic particles into sticky droplets with a high potential of adhering to surfaces. These experiments demonstrate both a large variability in the material properties of ash from Eyjafjallajökull volcano and a strong contrast to the behaviour of the test sands. In light of these differences, the application in volcanic crises of models of the impact of ash on operability of passenger jet turbines that have been based on test sand calibrations must be re-evaluated. We stress as well that ingestion tests should not only investigate the turbine's response to ash concentration (g/m 3 ) but also to ash dosage.

Volcanic ash is known to charge electrically, producing some of the most spectacular displays of lightning in nature. Here we investigate the electrical characteristics of ash from two different Icelandic volcanoes -Eyjafjallajökull in 2010 and Grímsvötn in 2011. Laboratory tests investigated the charge transferred to a conducting plate due to fall of volcanic ash through an insulating cylinder. Ash from the Eyjafjallajökull eruption was found to charge slightly positively, whilst Grímsvötn ash was substantially negatively charged. Measurement of the volumetric ratio of particle diameters showed the Eyjafjallajökull ash to have a bimodal distribution, and the Grímsvötn ash a monomodal distribution. Previous experiments with single-material particle systems show that smaller particles charge negatively and larger ones positively [e.g. Lacks and Levandovsky 2007]. Since charge is carried by individual particles, the charging is likely to be dominated by the number size distribution, therefore the large negative charge of the Grímsvötn ash is likely to be related to a large number of small particles within the number size distribution of the ash.

Volcanoes need to be monitored to mitigate the risk that they pose to society. This can be done on a global scale using satellite sensors. The goal of this doctorate was to develop methods for the monitoring of volcanic thermal activity from space. This was achieved through the use of a variety of orbital infrared sensors. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which offers moderate to high spatial resolution imagery (30 -90 m) in the short-wave infrared (SWIR) and thermal infrared (TIR), was used to characterize the size and intensity of thermal anomalies. Its TIR channels were capable of detecting subtle thermal anomalies. This permitted the observation of new thermal precursors to eruptive events. The Moderate Resolution Imaging Spectroradiometer (MODIS) offers high temporal resolution imagery (i.e. daily global coverage). It was therefore used to investigate thermal activity through time. Wavelet analysis was used to quantify the time period over which such activity oscillates. Hyperion is an orbiting imaging spectrometer. It was used to demonstrate a new method for calculating radiant flux from thermally heterogeneous targets (i.e. such as volcanoes). These methods utilized the strengths of each sensor system, i.e. high spatial, temporal or spectral resolution. They all improve the ability to detect and/or quantify thermal anomalies from space and can be executed in an automated global basis. This thesis therefore presents a solid foundation on which the next generation global volcano monitoring system can be based.

Volcanoes are associated with the movement of heat from the Earth's mantle to the surface. The ability to measure the temperature of volcanic targets from space would provide a particularly useful tool in furthering the understanding of volcanic systems. However this goal has remained difficult to obtain because of the heterogeneous nature of volcanoes and their ability to saturate sensor channels, especially those spanning through the infrared wavelengths that are sensitive to magmatic temperatures. We propose a new approach based on the Grey-body Emissivity Method and the similar atmospheric transmissivity of wavelengths within the thermal infrared (TIR) region at around 10-12 μm. This has allowed approximate temperature estimates of Lascar volcano to be made using ASTER bands 13 and 14. We find that eruptive events are generally associated with increases in temperature, which have been attributed to degassing events. The youngest temperature estimates show the summit crater has ceased to display elevated temperatures, this has followed the longest and warmest eruptive period. Thermal maps, created over Lascar's edifice, provide constraints on the spatial extent of the heat source. Future amendments to the model, so that atmospheric effects are quantitatively incorporated, are likely to allow the additional detection of temperatures at low altitudes as well.

1. Explosive volcanic eruptions are one of the few natural phenomena that can produce global catastrophic effects. On 4 June 2011, an eruption in the Puyehue volcanic complex (40°35′S, 72°06′W, Chile) discharged massive amounts of ash and pumice into the surrounding landscape in Argentina (North Andean Patagonia). The ejected material affected nearby aquatic environments, producing an increase in total suspended solids. 2. We combined field data and laboratory experiment data to determine the effect of the volcanic ashes suspended in the water column on cladoceran populations. 3. During the summer of 2011-2012 (6 months after the eruption), zooplankton populations in these lakes decreased, mainly due to the disappearance of cladocerans. This decrease in zooplankton was not caused by food shortage; chlorophyll a concentrations in the lakes were higher than in previous years or in the following season, and no change in phytoplankton size was observed. By the following summer (2013), 18 months after the eruption, a recovery of cladoceran populations was observed, with a concomitant decrease in total suspended solids. 4. We performed a life-table experiment, examining Daphnia commutata survival and fecundity at a series of ash concentrations. Ash concentrations of 2, 3, 5 and 8 mg L À1 negatively affected survival and fecundity. Populations exposed to 8 mg L À1 of ash cannot persist; these organisms fail to produce offspring because they die before reaching reproductive age. 5. We conclude that the disappearance of cladocerans was due to the presence of ash. As the sedimentation process occurs, ash concentrations decrease, favouring population recovery, as observed the following summer. When the lakes recovered their original transparency with low total suspended solids values, the cladoceran populations also returned to their historical abundances. 6. Previous data on other explosive volcanic eruptions and the present data indicate that immediately after ash fall, the zooplankton suffer reduced abundance, particularly of non-selective filter feeders such as daphnids. However, recovery of zooplankton population growth can be expected within a few years.

Although CO2 is generally the most abundant dissolved gas found in submarine hydrothermal fluids, it is rarely found in the form of CO2 liquid. Here we report the discovery of an unusual CO2‐rich hydrothermal system at 1600‐m depth near the summit of NW Eifuku, a small submarine volcano in the northern Mariana Arc. The site, named Champagne, was found to be discharging two distinct fluids from the same vent field: a 103°C gas‐rich hydrothermal fluid and cold (&lt;4°C) droplets composed mainly of liquid CO2. The hot vent fluid contained up to 2.7 moles/kg CO2, the highest ever reported for submarine hydrothermal fluids. The liquid droplets were composed of ∼98% CO2, ∼1% H2S, with only trace amounts of CH4 and H2. Surveys of the overlying water column plumes indicated that the vent fluid and buoyant CO2 droplets ascended &lt;200 m before dispersing into the ocean. Submarine venting of liquid CO2 has been previously observed at only one other locality, in the Okinawa Trough back‐arc ba...

This study uses the National Institutes of Health ImageJ software to investigate the colour variation and degree of compaction in paleosols developed on 3500–2600 BCE layers of volcanic ash in the excavation site for the new Chiaia Metro Station at Piazza Santa Maria degli Angeli in downtown Naples. Plough marks on the paleosols indicate agrarian activity during a 700-year period. The darkening toward the top of the paleosols, especially around root-like stringers extending down from the surface, is due almost exclusively to alteration of glass in pumice particles to clay minerals. Feldspar crystals in the same ash show no signs of alteration. One set of plough marks appears to be too regular and closely spaced (<12 cm) to have been formed by multiple passes with a single-bladed stick plough, raising the question of whether a multiple-pronged plough could have been used, even though no archeological evidence indicates their use at that time. Bent crystals of biotite indicate that the ashes underwent compaction. The preferred orientation of mineral grains indicate that all of the ashes underwent about 12% compaction, regardless of proximity to a ploughed surface. We conclude that the compaction was due to load pressure rather than to agrarian activity.

In recent years, many research works have been done to investigate the possibility of utilizing a broad range of materials as raw materials in the production of geopolymer cements. The use of artificial pozzolans or aluminosilicate-type industrial waste materials such as granulated blast-furnace slag and fly ash has been reported in many research works. Natural pozzolans are also aluminosilicate-type materials which can be activated with solutions of NaOH and Na 2 SiO 3 . Using a pumice-type natural pozzolan from Taftan Mountain located at the south east of Iran and different alkaliactivators based on combinations of Na 2 SiO 3 and NaOH, a number of natural-pozzolanbased geopolymer cement systems were designed and prepared. Final setting time, workability, and 28-day compressive strength of the systems were studied. The results obtained reveal that Taftan pozzolan can be activated using a proportioned mixture of Na 2 SiO 3 and NaOH resulting in the formation of a geopolymer cement system exhibiting suitable workability and relatively high 28-day compressive strengths up to 63 MPa.

A large volcanic eruption can generate large amounts of ash which affect the socio-economic activities of surrounding areas, affecting airline transportation, socio-economics activities, and human health. Accumulated ashfall has devastating impacts on areas surrounding the volcano and in other regions, and eruption scale and weather conditions may escalate ashfall hazards to wider areas. It is crucial to discover places with a high probability of exposure to ashfall deposition. Here, as a reference for ashfall disaster countermeasures, we present a dataset containing the estimated distributions of the ashfall deposit and airborne ash concentration, obtained from a simulation of ash dispersal following a large-scale explosive volcanic eruption. We selected the Taisho (1914) eruption of the Sakurajima volcano, as our case study. This was the strongest eruption in Japan in the last century, and our study provides a baseline for a worst-case scenario. We employed one eruption scenario (OES) approach by replicating the actual event under various extended weather conditions to show how it would affect contemporary Japan. We generated an ash dispersal dataset by simulating the ash transport of the Taisho eruption scenario using a volcanic ash dispersal model and meteorological reanalysis data for 64 years . We explain the dataset production and provide the dataset in multiple formats for broader audiences. We examine the validity of the dataset, its limitations, and its uncertainties. Countermeasure strategies can be derived from this dataset to reduce ashfall risk.

Setiap agregat memiliki karakteristik yang berbeda-beda dari satu wilayah dengan wilayah yang lain, bahkan dari satu lokasi dengan lokasi yang lain dalam wilayah yang sama. Kebanyakan konstruksi jalan di Wilayah Jabodetabek menggunakan material agregat yang bersumber dari tiga quarry di Jawa Barat yaitu Gunung Bitung, Gunung Rumpin, dan Gunung Sudamanik. Penelitian ini bertujuan untuk menganalisis perbandingan karakteristik campuran aspal material agregat dari tiga quarry tersebut melalui nilai karakteristik Marshall pada campuran beton aspal dengan menggunakan Spesifikasi Bina Marga Revisi III (2010). Metode eksperimental digunakan untuk mengetahui material agregat mana yang baik untuk konstruksi beton aspal dengan proporsi campuran agregat yaitu Agregat kasar 38%, Agregat Sedang 17% dan Agregat Halus 45% terhadap total campuran aspal yang telah ditentukan oleh Bina Marga (2010). Pengujian pada campuran aspal dengan material dari tiga quarry tersebut didapat kadar aspal optimum (KA...

Isarog Volcano is an active stratovolcano along the Bicol Volcanic Arc in Southern Luzon, Philippines, with a history of at least one sector collapse, post-collapse domes, and many block-and-ash flows. The present crater is breached to the east and the most recent deposits were most likely emplaced in this direction. The volcano’s eruptive history during the Holocene was reconstructed using field mapping, stratigraphy, and ¹⁴C dating. The primary deposits are block-and-ash flows that extend as far as 13 km to the east. Several flow units are >7 m thick and massive, characterized by angular juvenile blocks set in an ash matrix. These deposits are interpreted as products of multiple dome collapse events. A ~5 m thick bedded ash-rich deposit that crops out 15 km from the summit is interpreted as elutriated ash from multiple dome collapses. Each block-and-ash flow unit is separated by a paleosol indicating a period of repose between eruptions. The source domes could have grown inside or outside of the summit crater, and the eruptions of these occurred prior to the breaching of the crater that produced the Rangas lahar deposits to the east. We obtained new ¹⁴C dates spanning 4912 ± 64 cal yr BP to 766 ± 32 cal yr BP from charcoal samples collected from paleosols and block-and-ash flow deposits in Goa Terminal, Pugay, Napanap, and San Isidro, Camarines Sur. These ages are significantly younger than the previously determined age of 5397 ± 78 cal yr BP. The new ¹⁴C dates reveal at least four younger eruptions, including one during the 12th century CE and another about 2300 BCE. The far-reaching block-and-ash flows pose a previously unrecognized hazard to the communities around Isarog Volcano, and the identification of this threat is a vital contribution to hazard assessment.

A series of fieldworks were conducted in the municipality of Goa, Camarines Sur, Philippines from October 2019 to March 2020, focusing on areas that might be affected in a future eruption of Isarog Volcano – one of the 24 active volcanoes in the Philippines. The researcher gathered important data, including the measurement of the outcrops, its coordinates, and the identification of beds. Rock samples were taken from the field to undergo petrographic analysis and paleomagnetic polarity testing. Organic materials, such as charcoal, were also taken from one of the outcrops to undergo radiocarbon dating. The goal of the study is to identify the potential volcanic hazards in the municipality, and create a volcanic hazard map based on the data gathered from the field. Based on Fontijn and Newhall’s research in 2013, the rocks extruded by the volcano are mostly andesite, and an explosive eruption is possible. The downtown area of Goa, Camarines Sur – where the majority of the population lives – sits on block-and-ash flow deposits, a type of pyroclastic flow deposit. It was determined using a portable fluxgate magnetometer. The upper barangays near the foot of the volcano are more susceptible to ballistic projectiles and lava flow. Areas near the rivers are more prone to lahars. The municipality will most likely experience moderate to heavy ash fallout when the volcano erupts while the southwest monsoon (Habagat) is active. The radiocarbon dating of charcoal taken from the municipal transport terminal confirmed that Isarog Volcano erupted 4272-4384 cal yr bp (calibrated years before present). This event is more recent than the volcanic eruption discovered by Fontijn and Newhall in 2013, taking place 5320-5480/5550-5570 cal yr bp.

Thermal barrier coatings (TBCs) made of yttria stabilized zirconia (YSZ) have been applied to aero engines industry since 1970s. However, because of the increasing operational temperature, TBCs are suffering from molten foreign deposits known as calcium-magnesium-alumino-silicate (CMAS). Molten CMAS sinters YSZ top coat and shortens the lifetime of TBCs. Alumina has been widely proved to prevent CMAS from degradation and is the most common material chosen to avert a CMAS attack in state-of-the-art TBC technology. This study uses real volcanic ash to study the degradation process of TBCs and potential mitigation mechanisms. The results show that, similar to CMAS, volcanic ash severely penetrates the thickness and fills the columnar gaps of the TBC top coat. It is also found that the yttria content of the YSZ top coat decreases substantially with high temperature exposure to volcanic ash, which has a detrimental effect on the phase stability of YSZ. In terms of mitigation, volcanic ash reacts with alumina around 1310 °C , forming anorthite (CaAl 2 Si 2 O 8 ), magnetite (Fe 3 O 4 ), and spinel (Al 1.75 Mg 0.889 Mn 0.351 O 4 ) as reactive products, which, according to the literature, have melting temperatures above that of the volcanic ash studied and the typical values reported for CMAS. Since the new melting temperatures are now above the typical surface operating temperature of turbine components, the melting-induced penetration of volcanic ash and CMAS can be considerably suppressed.

Gravity currents in an ambient flow ANJA SLIM, HERBERT HUP-PERT, University of Cambridge -Gravity currents occur whenever fluid of one density flows, predominantly horizontally, into fluid of a different density. In natural and man-made situations they are frequently generated in the presence of a flowing ambient. For example, both volcanic ash clouds and toxic gas releases are affected by atmospheric winds, while river plumes and pollutant releases in the sea are affected by marine currents. We theoretically study the canonical problem of a homogeneous, high Reynolds number gravity current generated by a constant source in a uniform ambient flow. In order to model it we employ a shallow-water formulation and present both numerical and asymptotic solutions. Of interest is how the current evolves and its dimensions, particularly its maximum upstream extent. We also briefly describe unusual features of gravity currents generated by a slowly sedimenting particle load.