Search results for "METEOROLOGY"

Ultraviolet camera measurements of passive and explosive (Strombolian) sulphur dioxide emissions at Yasur volcano, Vanuatu

2020

Here, we present the first ultraviolet (UV) camera measurements of sulphur dioxide (SO2) flux from Yasur volcano, Vanuatu, for the period 6–9 July 2018. These data yield the first direct gas-measurement-derived calculations of explosion gas masses at Yasur. Yasur typically exhibits persistent passive gas release interspersed with frequent Strombolian explosions. We used compact forms of the “PiCam” Raspberry Pi UV camera system [1,2] powered through solar panels to collect images. Our daily median SO2 fluxes ranged from 4 to 5.1 kg s−1, with a measurement uncertainty of −12.2% to +14.7%, including errors from the gas cell calibration drift, uncertainties in plume direction and distance, and…

Comment on “Effects of different tillage practices on the hydraulic resistance of concentrated flow on the loess plateau in China” by J. Sun et al

2020

Abstract For concentrated flows, which are characterized by small water depth and steep sloping beds, hydraulic conditions different from those typical of streams and rivers occur. In this study a new theoretically deduced flow resistance equation was tested using the experimental data by Sun et al. for three different tilled surfaces (Manual Dibbling, MD, Manual Hoeing, MH, and Contour Drilling, CD). At first, the profile parameter-relationship, which is the relationship between the velocity profile parameter Γ, the channel slope and the flow Froude number, was calibrated using rill flow data by Di Stefano et al. Then, the applicability of this relationship was tested by the measurements o…

Mapping fumarolic fields in volcanic areas: A methodological approach based on the case study of La Fossa cone, Vulcano island (Italy)

2016

Abstract Changes in the activity state of a volcano can be inferred by monitoring the steam flux from fumarolic fields, in terms of 4D (x, y, z, time) variations in temperature and extension of the zone. During the last decades, several studies in this field have been conducted worldwide, and at Vulcano island (Italy) in particular. Both direct and remotely sensed measurements have been used for identifying thermally anomalous areas, but the possible role of the hydrothermal alteration of volcanic products, producing a sealing effect that obscures the surface thermal evidence of fumarolic activity, have never been explored. The novelty of the present study, carried out at La Fossa cone (Vul…

First observations of the fumarolic gas output from a restless caldera: Implications for the current period of unrest (2005-2013) at Campi Flegrei

2013

[1] The fumarolic gas output has not been quantified for any of the currently deforming calderas worldwide, due to the lack of suitable gas flux sensing techniques. In view of resumption of ground uplift (since 2005) and the associated variations in gas chemistry, Campi Flegrei, in southern Italy, is one of the restless calderas where gas flux observations are especially necessary. Here we report the first ever obtained estimate of the Campi Flegrei fumarolic gas output, based on a set of MultiGAS surveys (performed in 2012 and 2013) with an ad-hoc-designed measurement setup. We estimate that the current Campi Flegrei fumarolic sulphur (S) flux is low, on the order of 1.5–2.2 tons/day, sugg…

Geochemistry and SHRIMP U-Pb Zircon Dating of Mafic Rocks North of Zunhua City, Eastern Hebei, North China Craton: Paleoproterozoic Gabbro rather tha…

2018

A new approach for the measurement of gaseous elemental mercury (GEM) and H2S in air from anthropogenic and natural sources: Examples from Mt. Amiata…

2017

Real-time measurements of GEM and H2S discharged from natural and anthropogenic sources are a valuable tool to investigate the dispersion dynamics of these contaminants in air. In this study, a new approach to measure GEM and H2S concentrations in air, carried out by coupling a portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M) and a pulsed fluorescence gas analyzer (Thermo Scientific Model 450i), was applied to two distinct areas: (i) in the surroundings of Piancastagnaio (Siena, Central Italy), located in the eastern flanks of Mt. Amiata (a 200,000Â years old volcano), where three geothermal plants are operating and whose ex…

Late Holocene erosion of the Canopic promontory (Nile Delta, Egypt)

2017

International audience; The mouths of the Nile Delta are sensitive coastal areas, their geomorphology primarily being mediated by relative sea-level rise and sediment supply. To further document the Holocene evolution of the Nile's Canopic mouth, a core was taken from the southern shores of Abu Qir Bay, close to the ancient Canopic channel. Core bio-sedimentology and chronostratigraphy highlight four stages of marine incursion which are juxtaposed upon the general progradation trend of the Nile coast in this area. Compiled age-depth points from sediment cores taken in Abu Qir Bay underscore two phases of negative sediment budget at the Canopic mouth: (1) a first period, between 3.5 and 2 ka…

Lightning-induced weathering of Cascadian volcanic peaks

2020

Abstract The process of meteorological lightning-induced modification of coherent volcanic rocks is examined by geochemical, textural, and experimental analysis of fulgurites from South Sister volcano, Oregon Cascades, USA. Lightning's effects on volcanic target rocks was simulated with an arc-welding device in order to reproduce the geochemical and textural features of natural fulgurites and to constrain temperatures of melting and devolatilization behavior during lightning strikes. Melting of volcanic target rocks produces melts of exceptional compositional diversity, ranging from those with pure mineral compositions (e.g., diopside and plagioclase), resulting from congruent melting react…

Effects of glaciation on karst hydrology and sedimentology during the Last Glacial Cycle: The case of Granito cave, Central Pyrenees (Spain)

2021

In Alpine regions, speleothem development on karst systems largely occurs during warm interglacial or interstadial phases due to their limited growth during cold stages. Still, recent attention has been given to the role of clastic sediments in caves, less dependent on temperature conditions. Yet, only a small number of caves worldwide preserve both speleothems and detrital deposits. Here we present an outstanding record of fine-grain laminated sediments and carbonate speleothems from the Granito cave (South Central Pyrenees, Spain) associated with seasonal to annual hydroclimatic pulses through the Last Glacial Cycle (LGC). Analysis of cave clastic facies together with new absolute dates o…

Modeling of wind gap formation and development of sedimentary basins during fold growth: application to the Zagros Fold Belt, Iran

2016

Mountain building and landscape evolution are controlled by interactions between river dynamics and tectonic forces. Such interactions have been extensively studied, however a quantitative evaluation of tectonic/geomorphic feedbacks, which is imperative for understanding sediments routing within orogens and fold-and-thrust belts, remains to be undertaken. Here, we employ numerical simulations to assess the conditions of uplift and river incision necessary to deflect an antecedent drainage network during the growth of one, or several, folds. We propose that a partitioning of the river network into internal (endorheic) and longitudinal drainage arises as a result of lithological differences w…