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At least 163 records · Page 9

Volcanic Contribution to Decadal Changes in Tropospheric Temperature

Despite continued growth in atmospheric levels of greenhouse gases, global mean surface and tropospheric temperatures have shown slower warming since 1998 than previously. Possible explanations for the slow-down include internal climate variability, external cooling influences and observational errors. Several recent modelling studies have examined the contribution of early twenty-first-century volcanic eruptions to the muted surface warming. Here we present a detailed analysis of the impact of recent volcanic forcing on tropospheric temperature, based on observations as well as climate model simulations. We identify statistically significant correlations between observations of stratospheric aerosol optical depth and satellite-based estimates of both tropospheric temperature and short-wave fluxes at the top of the atmosphere. We show that climate model simulations without the effects of early twenty-first-century volcanic eruptions overestimate the tropospheric warming observed since 1998. In two simulations with more realistic volcanic influences following the 1991 Pinatubo eruption, differences between simulated and observed tropospheric temperature trends over the period 1998 to 2012 are up to 15% smaller, with large uncertainties in the magnitude of the effect. To reduce these uncertainties, better observations of eruption-specific properties of volcanic aerosols are needed, as well as improved representation of these eruption-specific properties in climate model simulations.

Atmospheric temperature↗

Total Volcanic Stratospheric Aerosol Optical Depths and Implications for Global Climate Change

Understanding the cooling effect of recent volcanoes is of particular interest in the context of the post-2000 slowing of the rate of global warming. Satellite observations of aerosol optical depth above 15 km have demonstrated that small-magnitude volcanic eruptions substantially perturb incoming solar radiation. Here we use lidar, Aerosol Robotic Network, and balloon-borne observations to provide evidence that currently available satellite databases neglect substantial amounts of volcanic aerosol between the tropopause and 15 km at middle to high latitudes and therefore underestimate total radiative forcing resulting from the recent eruptions. Incorporating these estimates into a simple climate model, we determine the global volcanic aerosol forcing since 2000 to be 0.19 +/- 0.09W/sq m. This translates into an estimated global cooling of 0.05 to 0.12 C. We conclude that recent volcanic events are responsible for more post-2000 cooling than is implied by satellite databases that neglect volcanic aerosol effects below 15 km.

aerosols↗

Cooling Rates of Lunar Volcanic Glass Beads

It is widely accepted that the Apollo 15 green and Apollo 17 orange glass beads are of volcanic origin. The diffusion profiles of volatiles in these glass beads are believed to be due to degassing during eruption (Saal et al., 2008). The degree of degassing depends on the initial temperature and cooling rate. Therefore, the estimations of volatiles in parental magmas of lunar pyroclastic deposits depend on melt cooling rates. Furthermore, lunar glass beads may have cooled in volcanic environments on the moon. Therefore, the cooling rates may be used to assess the atmospheric condition in an early moon, when volcanic activities were common. The cooling rates of glasses can be inferred from direct heat capacity measurements on the glasses themselves (Wilding et al., 1995, 1996a,b). This method does not require knowledge of glass cooling environments and has been applied to calculate the cooling rates of natural silicate glasses formed in different terrestrial environments. We have carried out heat capacity measurements on hand-picked lunar glass beads using a Netzsch DSC 404C Pegasus differential scanning calorimeter at University of Munich. Our preliminary results suggest that the cooling rate of Apollo 17 orange glass beads may be ~12 K/min, based on the correlation between temperature of the heat capacity curve peak in the glass transition range and glass cooling rate. The results imply that the parental magmas of lunar pyroclastic deposits may have contained more water initially than the early estimations (Saal et al., 2008), which used higher cooling rates, 60-180 K/min in the modeling. Furthermore, lunar volcanic glass beads could have been cooled in a hot gaseous medium released from volcanic eruptions, not during free flight. Therefore, our results may shed light on atmospheric condition in an early moon.

Hui, Hejiu↗

The Hazard of Volcanic Ash Ingestion

A research team of U.S. Government agencies and engine manufacturers conducted an experiment to test volcanic-ash ingestion by a NASA owned engine in the same family as the PW 2000 that was donated by the U.S. Air Force. The experiment, called Vehicle Integrated Propulsions Research (VIPR) test, was conducted under the auspices of NASAs Convergent Aeronautics Solutions (CAS) Program and took place in summer of 2015 at Edwards AFB in California as an on-ground, on-wing test. The primary objectives of the volcanic ash test were to determine the effect on the engine of several hours of exposure to low to moderate ash concentrations and to evaluate the capability of engine health management technologies for detecting these effects. The target concentrations of volcanic ash tested were at 1 and 10 mgm3. A natural volcanic ash was used that is representative of distal ash clouds many 100s to 1000 km from a volcanic source. The glassy ash particles were expected to soften and become less viscous when exposed to the high temperatures of the combustion chamber, then stick to the nozzle guide vanes of the high-pressure turbine and this was observed. Numerous observations and measurements of the engines performance and degradation were made during the course of the experiment, including borescope inspections after each test run. The engine has been disassembled so that detailed inspections of the engine effects have been made. A summary of the test methodology and execution will be made along with results from the test. While not intended to be sufficient for rigorous certification of engine performance when ash is ingested, the experiment should provide useful information to aircraft manufacturers, airline operators, and military and civil regulators in their efforts to evaluate the range of risks that ash hazards pose to aviation.

Lekki, John↗

A Decade of Global Volcanic SO2 Emissions Measured from Space

The global flux of sulfur dioxide (SO2) emitted by passive volcanic degassing is a key parameter that constrains the fluxes of other volcanic gases (including carbon dioxide, CO2) and toxic trace metals (e.g., mercury). It is also a required input for atmospheric chemistry and climate models, since it impacts the tropospheric burden of sulfate aerosol, a major climate-forcing species. Despite its significance, an inventory of passive volcanic degassing is very difficult to produce, due largely to the patchy spatial and temporal coverage of ground-based SO2 measurements. We report here the first volcanic SO2 emissions inventory derived from global, coincident satellite measurements, made by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite in 2005-2015. The OMI measurements permit estimation of SO2 emissions from over 90 volcanoes, including new constraints on fluxes from Indonesia, Papua New Guinea, the Aleutian Islands, the Kuril Islands and Kamchatka. On average over the past decade, the volcanic SO2 sources consistently detected from space have discharged a total of approximately 63 kt/day SO2 during passive degassing, or approximately 23 +/- 2 Tg/yr. We find that approximately 30% of the sources show significant decadal trends in SO2 emissions, with positive trends observed at multiple volcanoes in some regions including Vanuatu, southern Japan, Peru and Chile.

Carn, S. A.↗

Differences in the Evolution of Pyrocumulonimbus and Volcanic Stratospheric Plumes as Observed by CATS and CALIOP Space-Based Lidars

Recent fire seasons have featured volcanic-sized injections of smoke aerosols into the stratosphere where they persist for many months. Unfortunately, the aging and transport of these aerosols are not well understood. Using space-based lidar, the vertical and spatial propagation of these aerosols can be tracked and inferences can be made as to their size and shape. In this study, space-based CATS and CALIOP lidar were used to track the evolution of the stratospheric aerosol plumes resulting from the 2019–2020 Australian bushfire and 2017 Pacific Northwest pyrocumulonimbus events and were compared to two volcanic events: Calbuco (2015) and Puyehue (2011). The pyrocumulonimbus and volcanic aerosol plumes evolved distinctly, with pyrocumulonimbus plumes rising upwards of 10 km after injection to altitudes of 30 km or more, compared to small to modest altitude increases in the volcanic plumes. We also show that layer-integrated depolarization ratios in these large pyrocumulonimbus plumes have a strong altitude dependence with more irregularly shaped particles in the higher altitude plumes, unlike the volcanic events studied.

Kenneth Christian↗

Characterizing Martian Volcanic Provinces’ Magmatic Evolution and Chemistry through Equations of State Modeling Initial Study

Here we discuss a novel interdisciplinary approach to investigating igneous compositions of large volcanic provinces on Mars using remote sensing data sets (Mars Odyssey Gamma Ray and neutron Spectrometer suite--GRS, and gravity) to inform petrologic and thermoelastic modeling. Martian volcanic provinces, starting from Noachian to Amazonian age, including Elysium (EVP), are locations of great geologic interest which have been active over long time scales from Hesperian to Amazonian. Regional scale change in eruptive processes are poorly understood. Compared to large igneous provinces on Earth, the martian volcanic activity has persisted for orders of magnitude longer. Therefore, changes in mantle chemistry, pressure, and temperature during lithospheric cooling are expected to produce significant changes in the conditions of magma production, storage and ascent, affecting the degree of fractional crystallization and crustal contamination. In this study, we perform a detailed modeling to test the hypothesis that compositional variability within volcanic provinces resulted from spatiotemporal changes in the depth of magma formation and present initial results. Our methods include constraining the pressure and temperature conditions of EVP as a case study of geologically recent magmatic evolution on Mars using GRS informed surface chemistry constraints and pMELTS modeling. Second, we place constraints on the density and seismic velocities of the EVP melt through thermoelastic modeling with a local gravity analysis. This analysis is also extended to Noachian aged volcanic provinces on Mars initial results estimates mantle pressure for each sub-region is 16 kbar pressure, whereas, degree of partial melting is low and varies between 10 to 12. This study aims to validate our theoretical model and develop a perspective view of spatiotemporal changes at the interior of Mars throughout the time.

Martian science, Mars, geology, geophysics↗

Evidence for Present Day Volcanism on Venus: A Case Study of Idunn Mons

Idunn Mons in Imdr Regio on Venus is perhaps one of the best studied volcanoes on Venus in part due to having both radar and night-time emissivity data of the region [1-3]. Smrekar et al. [1] first presented night-time emissivity data of Idunn Mons from the VIRTIS instrument on Venus Express, which showed that some lava flows have high emissivity consistent with unweathered basalt. Smrekar et al. [1], based on known weathering rates at that time, suggested that the lava flows were less than 2.5 million years old and possible as young as 250,000 years old. However, recent experimental work has shown that basaltic rocks and associated minerals in contact with the Venusian caustic atmosphere would react quickly to produce rinds of alteration materials coating the surface and obscure emissivity signatures of igneous minerals within a few to ~10,000 years [4-9]. These new experimentally derived weathering and oxidation rates were used to suggest that lava flows at Idunn Mons with unweathered signatures are quite young and Idunn Mons may be volcanically active today [4, 8]. Independent geologic mapping and related stratigraphic reconstruction over the study area is consistent with the experimental results [2, 10]. Considering all the available evidence, we have taken a comprehensive approach combining these recent experimental results with previous orbital night-time emissivity, as well as atmospheric measurements, to constrain the evolution of Idunn Mons [3,10]. Our results suggest that Idunn Mons is both volcanically and tectonically active today, and that volcanism and tectonic activity are likely related [11]. Venus being volcanically active has been suggested at other volcanic centers, as well [e.g. 12-17]. Therefore, we use Idunn Mons specifically as a case study of a potentially active volcano that may be detectable by the upcoming fleet of missions that will be arriving at Venus in the next decade.

Justin Filiberto↗

Gina Crater Area, Venus: Multiple Overlapping Deformation and Volcanic Events Suggest Complex Active Tectonics

A current controversy in the geology of Venus centers on the age(s) of its highlands – the tesserae. One view of Venus’ past is that it experienced a global resurfacing event at 700-800 Myr, now represented mostly by volcanic plains, and that the tesserae represent earlier crust deformed in that event. It is also argued that the resurfacing represents multiple volcanic events over long times. The ancient age of tesserae has recently come into question. Some tesserae include distinct morphologic units that could represent deformed plains material; in other cases it is possible that tesserae are forming today. To address this question, we are mapping a tessera-plains transition around Gina Crater, near Venus’ north pole. Gina is a ~15 km diameter crater at 78.1°N, 76.3°E (Fig. 1), in the Snegurochka (V1) quadrangle. Gina is on the western boundary of the Szél-anya Lineae belt (mapped mostly as tessera), where it abuts a broad area of regional volcanic plains. The area is complex, with evidence for multiple episodes of tectonism and volcanism and was specifically chosen to help constrain the timing of deformation events relative to those of volcanic emplacement.

Emily K Roberts↗

Organic Entrainment and Preservation in Volcanic Glasses

Unaltered pyroclastic deposits have previously been deemed to have "low" potential for the formation, concentration and preservation of organic material on the Martian surface. Yet volcanic glasses that have solidified very quickly after an eruption may be good candidates for containment and preservation of refractory organic material that existed in a biologic system pre-eruption due to their impermeability and ability to attenuate UV radiation. Analysis using NanoSIMS of volcanic glass could then be performed to both deduce carbon isotope ratios that indicate biologic origin and confirm entrainment during eruption. Terrestrial contamination is one of the biggest barriers to definitive Martian organic identification in soil and rock samples. While there is a greater potential to concentrate organics in sedimentary strata, volcanic glasses may better encapsulate and preserve organics over long time scales, and are widespread on Mars. If volcanic glass from many sites on Earth could be shown to contain biologically derived organics from the original environment, there could be significant implications for the search for biomarkers in ancient Martian environments.

glass from lava domes↗

Diverse Eruptions at Approximately 2,200 Years B.P. on the Great Rift, Idaho: Inferences for Magma Dynamics Along Volcanic Rift Zones

Compositionally and morphologically diverse lava flows erupted on the Great Rift of Idaho approximately 2.2 ka (kilo-annum, 1000 years ago) during a volcanic "flare-up" of activity following an approximately 2 ky (kiloyear, 1000 years) hiatus in eruptions. Volcanism at Craters of the Moon (COTM), Wapi and Kings Bowl lava fields around this time included primitive and evolved compositions, separated over 75 kilometers along the approximately 85 kilometers-long rift, with striking variability in lava flow emplacement mechanisms and surface morphologies. Although the temporal associations may be coincidental, the system provides a planetary analog to better understand magma dynamics along rift systems, including that associated with lunar floor-fractured craters. This study aims to help bridge the knowledge gap between ancient rift volcanism evident on the Moon and other terrestrial planets, and active rift volcanism, e.g., at Hawai'i and Iceland.

RIFT ZONEs↗

Stratigraphy of the Caloris Basin, Mercury: Implications for Volcanic History and Basin Impact Melt

Caloris basin, Mercury's youngest large impact basin, is filled by volcanic plains that are spectrally distinct from surrounding material. Post-plains impact craters of a variety of sizes populate the basin interior, and the spectra of the material they have excavated enable the thickness of the volcanic fill to be estimated and reveal the nature of the subsurface. The thickness of the interior volcanic plains is consistently at least 2.5 km, reaching 3.5 km in places, with thinner fill toward the edge of the basin. No systematic variations in fill thickness are observed with long-wavelength topography or azimuth. The lack of correlation between plains thickness and variations in elevation at large horizontal scales within the basin indicates that plains emplacement must have predated most, if not all, of the changes in long-wavelength topography that affected the basin. There are no embayed or unambiguously buried (ghost) craters with diameters greater than 10 km in the Caloris interior plains. The absence of such ghost craters indicates that one or more of the following scenarios must hold: the plains are sufficiently thick to have buried all evidence of craters that formed between the Caloris impact event and the emplacement of the plains; the plains were emplaced soon after basin formation; or the complex tectonic deformation of the basin interior has disguised wrinkle-ridge rings localized by buried craters. That low-reflectance material (LRM) was exposed by every impact that penetrated through the surface volcanic plains provides a means to explore near-surface stratigraphy. If all occurrences of LRM are derived from a single layer, the subsurface LRM deposit is at least 7.5-8.5 km thick and its top likely once made up the Caloris basin floor. The Caloris-forming impact would have generated a layer of impact melt 3-15 km thick; such a layer could account for the entire thickness of LRM. This material would have been derived from a combination of lower crust and upper mantle.

Cratering↗

Dispersion and Aging of Volcanic Aerosols after the La Soufriere Eruption in April 2021

Volcanic aerosols change the atmospheric composition and thereby affect weather and climate. Aerosol dynamic processes such as nucleation, condensation, and coagulation modify the shape, size, and mass of aerosol particles, which influence their atmospheric lifetime and radiative properties. Nevertheless, most models omit these processes for ash particles. In this work, we explore the ash aerosol aging and sulfate production during the first 4 days following the 2021 La Soufrière (St. Vincent) eruption with the ICON-ART model (ICOsahedral Nonhydrostatic model with Aerosol and Reactive Trace gases). Online coupling of ICON-ART with a one-dimensional volcanic plume model calculates volcanic emission, which makes it possible to resolve the different eruption phases of the noncontinuous La Soufrière eruption. We compared our simulated aerosol distribution and composition with observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument, the Multiangle Imaging SpectroRadiometer (MISR) Research Aerosol (RA) Algorithm, and the Barbados Cloud Observatory (BCO). We show that online coupling is essential to adequately model the emissions and plume development close to the volcano. The modeled aerosol aging is in very good agreement with observations from MISR near the emission source and with CALIOP at larger distances. Furthermore, particle aging occurs faster in the troposphere than in the stratosphere due to the availability of water vapor and OH, but a layer of coated ash appears at the plume top due to faster oxidation of SO2 and lofting by aerosol-radiation interaction. This paper gives the first direct comparison of aerosol aging in volcanic eruption plumes between simulations and observations

volcanic aerosols↗

Differentiation and volcanism in the lunar highlands - Photogeologic evidence and Apollo 16 implications.

Study of materials of possible volcanic origin in the lunar highlands, including highland plains materials, materials forming closely spaced hills in which summit furrows and chains of craters are common, and materials forming closely spaced hills (some of which parallel the lunar grid) on which summit furrows and chain craters are rare. The highland plains materials probably are basaltic lavas with less Fe and Ti than the mare plains materials. The two hilly units appear to consist of materials that, if volcanic, were more viscous in the molten state than any of the lunar plains units; thus these materials may be significantly enriched in felsic components. Most of the highland materials of possible volcanic origin formed after the Imbrium multiring basin but before mare material completed flooding parts of the moon; they therefore postdate accretion of the moon and may represent several episodes of pre-mare volcanism.

Trask, n. J.↗

Identification, distribution and significance of lunar volcanic domes.

Over 300 previously unrecognized volcanic domes were identified on Lunar Orbiter photographs using the following criteria: (1) the recognition of land forms on the Moon similar in morphology to terrestrial volcanic domes, (2) structural control, (3) geomorphic discordance, and (4) the recognition of land forms modified by dome-like swellings. Many terrestrial volcanic domes are similar in morphology to lunar domes. This analogy suggests that some lunar hills are in fact extrusive volcanic domes. Many of the domes identified in this paper seem to be related to basins and craters, and with the exception of local tectonic grid control few domes are related to any observable Moon-wide pattern.

Smith, E. I.↗

Application of ERTS imagery to geologic mapping in the volcanic terrane of northwest Wyoming

The author has identified the following significant results. ERTS-1 image interpretations in the Yellowstone/Absaroka volcanic province indicate that the ERTS-1 imagery can be successfully employed in mapping large-scale structures and gross lithologic differences within the volcanic rocks. The volcanic rocks are readily separable from the sedimentary and crystalline rocks but the various volcanic units are seldom distinguishable unless they exhibit a characteristic morphology. Color anomalies were detected on the ERTS-1 imagery and found to be related to zones of alteration and mineralization. High altitude aircraft imagery provided a means of checking and improving the interpretations.

Breckenridge, R. M.↗

Synopsis of volcanic stratigraphy

Volcanic stratigraphic units are mappable layered units composed of volcanic rocks that are formed on land (subaerially) or under water (subaqueously) by volcanic processes. At least ten different types of volcanic stratigraphic units are recognized. The characteristics for each are discussed briefly and some typical examples are illustrated by diagrams to show their salient features.

Hammond, P. E.↗

Mercurian volcanism questioned

It is noted that reports of the Mariner 10 television team favor a volcanic origin for the plains materials on Mercury. The present paper advances the argument that the Mercurian plains more closely resemble the lunar light plains (which are not of volcanic origin) in terms of stratigraphic relations, surface morphology, and albedo contrast. It is suggested that the plains on Mercury may have been formed from impact materials, possibly impact melts or other basin ejecta which behaved more like a fluid than did the lunar ejecta. It is concluded that if the old intercrater plains and younger smooth plains of Mercury were formed from impact materials, then Mercury underwent neither the volcanic interlude between early cratering episodes nor the late mare-type volcanic phase deduced by the Mariner 10 investigators.

Wilhelms, D. E.↗