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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Pyroclastic Deposits on Venus as Indicators of the Youngest Volcanism

While most of the surface of Venus formed by effusive volcanic processes, deposits suggesting eruption styles that distribute airfall debris over large areas, or ground-hugging flows from plume collapse, are not common. Prior work notes radar-bright units with diffuse margins, generally consistent with a plume collapse emplacement model, in Eistla Regio, Dione Regio, and near Sappho Patera. We examine these deposits, and map additional occurrences, using Magellan data and Earth-based polarimetric radar maps from 1988, 2012, and 2015 observations.

Youngest↗
NASA NTRS2021

Response of the Quasi-Biennial Oscillation to historical volcanic eruptions

The impact of volcanic eruptions on surface climate is well-appreciated, but their in situ impact on the Quasi-Biennial Oscillation (QBO) has received comparatively little attention. This study examines the QBO responses to Krakatoa and Pinatubo using five configurations of the NASA Goddard Institute for Space Studies (GISS) Model E2.2 and MERRA-2 reanalysis. A dynamically consistent response is found in terms of static stability, zonal wind, and upwelling. Eruptions are found to bias the QBO towards a westerly state, such that the QBO period response depends upon the phase at the time of eruption. The QBO does not have a clear amplitude response to an eruption, based on these simulations. The underlying mechanisms appear not to be influenced to fi rst-order by interactive composition, sea surface temperatures, or long-term trends in CO2 and ozone-depleting substances.

volcanic eruptions↗
NASA NTRSDate not supplied

Large Scale Volcanism: An Explanation for the Heat-death of Venus-like Worlds

Large scale volcanism has played a critical role in the long-term habitability of Earth and possibly Venus. Large Igneous Provinces (LIPs) are in fact the cause of most major extinction events in Earth’s history, contrary to the popular belief about the devastation from large bolides. We examine the timing of Large Igneous Provinces (LIPs) through Earth’s history [1] to estimate the likelihood of nearly simultaneous events that could drive a planet into an extreme moist or runaway greenhouse, quenching subductive plate tectonics. Such events would end volatile cycling and may have driven Venus from a cool temperate state into the heat-death we see today. Using the Earth's LIP record [1] we have found that LIP events are distributed randomly throughout the past 3 billion years. A conservative estimate of the rate of LIPs in a random history statistically the same as Earth’s, pairs and triplets of LIPs closer in time than 0.1-1 million years are likely. This simultaneity threshold is significant to the extent that it is less than the time over which environmental effects have been shown to persist, for example in the Siberian Traps record [2,3]. With the recent mission selections of VERITAS and EnVision it may be possible for their high resolution radar maps to distinguish LIPs in the surface record we can see today on Venus.

Large Igneous Provinces↗
NASA NTRSDate not supplied

Aerosol observations from SAGE III on the International Space Station: Visualizing Wildfires and Volcanic Eruptions

The Stratospheric Gas and Aerosol Experiment (SAGE III) aboard the International Space Station has been monitoring ozone, aerosols, and other trace gases in the stratosphere and troposphere since its 2017 launch. This NASA hyperwall presentation focuses on aerosol observations from SAGE, demonstrating its ability to observe volcanic eruptions and increasingly frequent wildfires in recent years, like Raikoke in the Kuril Islands and the western US fires. [Note that presentation would be made on the NASA hyperwall, so not all captions visible to the viewer can be viewed in the PDF.]

SAGE III↗
NASA NTRS2024

Detection of Extensive Equatorial Plasma Depletions after the 2022 Tongan Volcanic Eruption from Multiple Geodetic Satellite Ranging Systems

We present a number of unique observations of ionospheric anomalies following the Hunga-Tonga Hunga-Ha'apai (HTHH) volcanic eruption on 15 January 2022. All are based on non-dedicated geodetic satellite systems: Global Positioning System tracking of Low Earth Orbit (LEO) CubeSats, intersatellite tracking between two GRACE Follow-On satellites, satellite radar altimeters to the ocean surface, and Doppler radio beacons from ground stations to LEO geodetic satellites. Their observations revealed the development of anomalously large trough-like plasma depletions, along with plasma bubbles, in the equatorial regions of the Pacific and East Asian sectors. Trough-like plasma depletions appeared to be confined within approximately ±20° magnetic latitude, accompanied by density enhancements just outside this latitude range. These plasma depletions and enhancements were aligned with the magnetic equator and occurred across broad longitudes. They were detected in regions where atmospheric waves from the HTHH eruption passed through around the time of the sunset terminator. We interpret these phenomena in terms of the E dynamo electric fields driven by atmospheric waves from the eruption. The uplift of the ionosphere beyond satellite altitudes, followed by subsequent plasma diffusion to higher latitudes along magnetic field lines, results in the formation of trough-like plasma depletions around the magnetic equator and density enhancement at higher latitudes. The detection of plasma bubbles in the Asian sector during the non-bubble season (January) is likely associated with the uplift of the ionosphere at the sunset terminator.

Sentinel-3B↗
DOE OSTI2021

Heterogeneous multiphase flow properties of volcanic rocks and implications for noble gas transport from underground nuclear explosions

Of interest to the Underground Nuclear Explosion Signatures Experiment are patterns and timing of explosion-generated noble gases that reach the land surface. The impact of potentially simultaneous flow of water and gas on noble gas transport in heterogeneous fractured rock is a current scientific knowledge gap. This article presents field and laboratory data to constrain and justify a triple continua conceptual model with multimodal multiphase fluid flow constitutive equations that represents host rock matrix, natural fractures, and induced fractures from past underground nuclear explosions (UNEs) at Aqueduct and Pahute Mesas, Nevada National Security Site, Nevada, USA. Capillary pressure from mercury intrusion and direct air–water measurements on volcanic tuff core samples exhibit extreme spatial heterogeneity (i.e., variation over multiple orders of magnitude). Petrographic observations indicate that heterogeneity derives from multimodal pore structures in ash-flow tuff components and post-depositional alteration processes. Comparisons of pre- and post-UNE samples reveal different pore size distributions that are due in part to microfractures. Capillary pressure relationships require a multimodal van Genuchten (VG) constitutive model to best fit the data. Relative permeability estimations based on unimodal VG fits to capillary pressure can be different from those based on bimodal VG fits, implying the choice of unimodal vs. bimodal fits may greatly affect flow and transport predictions of noble gas signatures. The range in measured capillary pressure and predicted relative permeability curves for a given lithology and between lithologies highlights the need for future modeling to consider spatially distributed properties.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2022

Parameter estimation from spontaneous imbibition into volcanic tuff

Two-phase fluid flow properties underlie quantitative prediction of water and gas movement, but constraining these properties typically requires multiple time-consuming laboratory methods. The estimation of two-phase flow properties (van Genuchten parameters, porosity, and intrinsic permeability) is illustrated in cores of vitric nonwelded volcanic tuff using Bayesian parameter estimation that fits numerical models to observations from spontaneous imbibition experiments. The uniqueness and correlation of the estimated parameters is explored using different modeling assumptions and subsets of the observed data. The resulting estimation process is sensitive to both moisture retention and relative permeability functions, thereby offering a comprehensive method for constraining both functions. The data collected during this relatively simple laboratory experiment, used in conjunction with a numerical model and a global optimizer, result in a viable approach for augmenting more traditional capillary pressure data obtained from hanging water column, membrane plate extractor, or mercury intrusion methods. This method may be useful when imbibition rather than drainage parameters are sought, when larger samples (e.g., including heterogeneity or fractures) need to be tested that cannot be accommodated in more traditional methods, or when in educational laboratory settings.

58 GEOSCIENCES↗
DOE OSTI2020

Pseudomonas atagosis sp. nov., and Pseudomonas akappagea sp. nov., New Soil Bacteria Isolated from Samples on the Volcanic Island Izu Oshima, Tokyo

During the exploration of microbial natural resources, two strains of Pseudomonas, PS14 T and PS24 T , were isolated from samples taken from Izu Oshima, a volcanic island located 120 km southwest of central Tokyo. Phylogenetic analysis based on 16S rRNA gene sequences showed that PS14 T was most similar to Pseudomonas baetica a390T (99.6%) and Pseudomonas helmanticensis OHA11 T (99.5%), and that PS24T was most similar to Pseudomonas qingdaonensis JJ3 T (98.8%) and Pseudomonas lutea OK2 T (98.7%). The major fatty acids of these two strains were C 16:0 and C 17:0 cyclo, summed feature 3 (C 16:1 ω6c and/or C 16:1 ω7c), and summed feature 8 (C18:1 ω7c and/or 18:1 ω6c). The phylogenetic analyses, DNA-DNA hybridization results and phenotypic traits indicated that PS14 T and PS24 T constitute two novel species, Pseudomonas atagosis sp. nov. (type strain PS14 T = CECT 9940 T , = LMG 31496 T ) and Pseudomonas akappagea sp. nov. (type strain PS24T = CECT 9941T, = LMG 31497T), respectively. The sequence data of the draft genomes of PS14 T and PS24 T were deposited in the GenBank database under accession numbers VXCA00000000 and VXCP00000000, respectively, and the sequence data of their 16S rRNA genes were deposited in the GenBank database under accession numbers MN396717 and MN382268, respectively.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Stressful crystal histories recorded around melt inclusions in volcanic quartz

Abstract Magma ascent and eruption are driven by a set of internally and externally generated stresses that act upon the magma. We present microstructural maps around melt inclusions in quartz crystals from six large rhyolitic eruptions using synchrotron Laue X-ray microdiffraction to quantify elastic residual strain and stress. We measure plastic strain using average diffraction peak width and lattice misorientation, highlighting dislocations and subgrain boundaries. Quartz crystals across studied magma systems preserve similar and relatively small magnitudes of elastic residual stress (mean 53–135 MPa, median 46–116 MPa) in comparison to the strength of quartz (~ 10 GPa). However, the distribution of strain in the lattice around inclusions varies between samples. We hypothesize that dislocation and twin systems may be established during compaction of crystal-rich magma, which affects the magnitude and distribution of preserved elastic strains. Given the lack of stress-free haloes around faceted inclusions, we conclude that most residual strain and stress was imparted after inclusion faceting. Fragmentation may be one of the final strain events that superimposes stresses of ~ 100 MPa across all studied crystals. Overall, volcanic quartz crystals preserve complex, overprinted deformation textures indicating that quartz crystals have prolonged deformation histories throughout storage, fragmentation, and eruption.

58 GEOSCIENCES↗
DOE OSTI2020

Iodine effective diffusion coefficients through volcanic rock: Influence of iodine speciation and rock geochemistry

Accurate prediction of the subsurface transport of iodine species is important for the assessment of long-term nuclear waste repository performance, as well as monitoring compliance with the Comprehensive Nuclear-Test-Ban Treaty, given that radioiodine decays into radioxenon. However, the transport of iodine through intact geologic media is not well understood, compromising our ability to assess risk associated with radioiodine migration. The current study's goal is to quantify the matrix diffusion of iodine species through saturated volcanic rock, with particular attention paid to the redox environment and potential speciation changes. Here, diffusion experiments were run for iodide through lithophysae-rich lava, lithophysae-poor lava, and welded tuff, whereas iodate diffusion was studied through welded tuff. Iodine transport was compared with a conservative tracer, HDO, and effective diffusion coefficients were calculated. Likely due to a combination of size and anion exclusion effects, iodine species diffused more slowly than the conservative tracer through all rock types tested. Furthermore, oxidation of iodide to iodate was observed in the lithophysae-poor lava, affecting transport. Results provide much needed data for subsurface transport models that predict radioiodine migration from underground sources, and indicate the pressing need for geochemical and redox interactions to be incorporated into these models.

58 GEOSCIENCES↗
DOE OSTI2022

Manganese Oxidation States in Volcanic Soils across Annual Rainfall Gradients

Manganese (Mn) exists as Mn(II), Mn(III), or Mn(IV) in soils, and the Mn oxidation state controls the roles of Mn in numerous environmental processes. However, the variations of Mn oxidation states with climate remain unknown. Here we determined the Mn oxidation states in highly weathered bulk volcanic soils (primary minerals free) across two rainfall gradients covering mean annual precipitation (MAP) of 0.25–5 m in the Hawaiian Islands. With increasing MAP, the soil redox conditions generally shifted from oxic to suboxic and to anoxic despite fluctuating at each site; concurrently, the proportions of Mn(IV) and Mn(II) decreased and increased, respectively. Mn(III) was low at both low and high MAP, but accumulated substantially, up to 80% of total Mn, in soils with prevalent suboxic conditions at intermediate MAP. Mn(III) was likely hosted in Mn(III,IV) and iron(III) oxides or complexed with organic matter, and its distribution among these hosts varied with soil redox potentials and soil pH. Soil redox conditions and rainfall-driven leaching jointly controlled exchangeable Mn(II) in soils, with its concentration peaking at intermediate MAP. The Mn redox chemistry was at disequilibrium, with the oxidation states correlating with long-term average soil redox potentials better than with soil pH. The soil redox conditions likely fluctuated between oxic and anoxic conditions more frequently at intermediate than at low and high MAP, creating biogeochemical hot spots where Mn, Fe, and other redox-sensitive elements may be actively cycled.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Observations Show Charge Density of Volcanic Plumes is Higher Than Thunderstorms

We analyze slow electric field change and lightning mapping measurements to provide insight into the characteristics of volcanic lightning and the associated implications on charging processes and the charge structure of a Vulcanian eruption plume. Data were obtained during a multi-instrumental field campaign at Sakurajima volcano in 2015 when the Showa crater was active. We combine the electric field change and lightning mapping data from one explosive eruption on June 6, 2015 to identify individual flashes. From this, we interpret the flash type and polarity. In addition, the long-time constant of the electric field change instrument allowed measurement of the quasi-static field associated with charge separation in the eruption plume. We find that both intracloud and cloud-to-ground discharges occurred, and the polarity of cloud-to-ground discharges were all negative. The quasi-static field measurement showed the plume carried a net negative charge. We calculate both the total charge transferred by cloud-to-ground discharges and the net charge density of the eruption plume. We find that cloud-to-ground discharges transfer an average of –0.41C per flash and the net charge density was –33C/ km 3 . Here, the percent error is at least 200%, due to uncertainty in the antenna gain. We show that these estimates are consistent with lightning that is 100 m in length. Further, the average flash rate during the first 8 s following the onset of eruption was five flashes per second. After that time, the flash rate abruptly decreased, which may be related to the end of gas-thrust forcing.

58 GEOSCIENCES↗
DOE OSTI2025

Permeability scaling relationships of volcanic tuff from core to field scale measurements

A recent chemical explosive test in P-Tunnel at the Nevada National Security Site, Nevada, USA, was conducted to better understand how signals propagate from explosions in the subsurface. A primary signal of interest is the migration of gases that can be used to differentiate chemical from nuclear explosions. Gas migration is highly dependent on the rock permeability which is notoriously difficult to determine experimentally in the field due to a potentially large dependence on the scale over which measurements are made. Here, we present pre-explosion permeability estimates to characterize the geologic units surrounding the recent test. Permeability measurements were made at three scales of increasing size: core samples (≈2 cm), borehole packer system tests (≈1 m), and a pre-shot cavity pressurization test (> 10 m) across ten tuff units. Permeability estimates based on core measurements showed little difference from borehole packer tests. However, permeability in most rock units calibrated from cavity pressurization tests resulted in higher permeability estimates by up to two orders of magnitude. Here, we demonstrate that the scale of the measurement significantly impacts the characterization efforts of hydraulic properties in volcanic tuff, and that local-scale measurements (< 10 m scale) do not incorporate enough heterogeneity to accurately predict field-scale flow and mass transport.

Environmental sciences↗
DOE OSTI2026

Characterization of volcanic tuff pores pre- and post-underground nuclear detonation using ultra-small and small angle neutron scattering

The ability to accurately model the subsurface transport of radionuclides is fundamental to the remote detection and characterization of underground nuclear explosion (UNE) events. Developing more sophisticated transport models presents a significant opportunity to enhance monitoring capabilities, particularly in the reliable prediction of signature migration. Experimentally determined characterization of geologic materials associated with transport properties is the pertinent base information for such robust model development and calibration. Here, we report results from an unprecedented study demonstrating changes to the pore and fracture network structures in geological materials in response to UNEs over nanometer to micrometer length scales. Volcanic tuffs of five different lithological formations from pre- and post-UNE environments were collected from the Nevada National Security Site. Combined ultra-small and small-angle neutron scattering techniques were used to characterize the tuff pore structure. The results demonstrate measurable differences in the specific surface area and porosity of samples pre- and post-shot from texturally similar lithological formations, indicating that pore properties can serve as a direct physical signature of a UNE. The results also provide experimentally determined transport parameters in support of advanced model development through the integration of gas migration, hydrodynamic simulations, and geologic framework models.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Volcanic arc rigidity variations illuminated by coseismic deformation of the 2011 Tohoku-oki M9

Rock strength has long been linked to lithospheric deformation and seismicity. However, independent constraints on the related elastic heterogeneity are missing, yet could provide key information for solid Earth dynamics. Using coseismic Global Navigation Satellite Systems (GNSS) data for the 2011 M9 Tohoku-oki earthquake in Japan, we apply an inverse method to infer elastic structure and fault slip simultaneously. We find compliant material beneath the volcanic arc and in the mantle wedge within the partial melt generation zone inferred to lie above ~100 km slab depth. We also identify low-rigidity material closer to the trench matching seismicity patterns, likely associated with accretionary wedge structure. Along with traditional seismic and electromagnetic methods, our approach opens up avenues for multiphysics inversions. Those have the potential to advance earthquake and volcano science, and in particular once expanded to InSAR type constraints, may lead to a better understanding of transient lithospheric deformation across scales.

58 GEOSCIENCES↗
DOE OSTI2022

Non-cratonic Diamonds from UHP Metamorphic Terranes, Ophiolites and Volcanic Sources

The discovery of diamonds in metamorphic rocks of continental affinities occurred shortly after the discovery of coesite in similar rocks. These important discoveries led to a revolution in our understanding of the subduction and exhumation of continental materials and the establishment of a new discipline, ultra-high-pressure metamorphism (UHPM). After these discoveries more ultra-high pressure (UHP) minerals were found and dozens of UHPM terranes were established. Diamond is a remarkable material which is chemically inert and stable over geological timescales making it the perfect “geological container” where gas, fluid, and solid inclusions can be preserved. Moreover, its presence is indicative of specific pressure and temperature conditions which implie subduction to a minimum depth of ~120 km. The inclusions trapped inside these diamonds can shed light on the composition, redox state, and evolution of the fluids related to UHPM diamond formation while the carbon isotope ratios of the diamond itself can inform us about the source of carbon. The purpose of this review is to provide a brief history on the discovery of microdiamonds starting with work that began in the mid-1960s in Kokchetav massif, Kazakhstan, through to the present day. Particular attention will be on more recent micro-diamond discoveries in the last decade. The current state of understating of the mechanisms of UPHM diamond formation, the misidentification of microdiamonds due to contamination from sample extraction/preparation, and the future of UHPM diamond research are discussed. The paper also considers the controversial topic of the occurrence of lonsdaleite within the population of microdiamonds from UHPM terranes as well as recently reported ophiolite- and volcanic-hosted diamonds.

58 GEOSCIENCES↗