Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “tectonics”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

Glacially Induced Faulting in Alaska

Southern Alaska provides an ideal setting to assess how surface mass changes can influence crustal deformation and seismicity amidst rapid tectonic deformation. Since the end of the Little Ice Age, the glaciers of southern Alaska have undergone extensive wastage, retreating by kilometers and thinning by hundreds of meters. Superimposed on this are seasonal mass fluctuations due to snow accumulation and rainfall of up to meters of equivalent water height in fall and winter, followed by melting of gigatons of snow and ice in spring and summer and changes in permafrost. These processes produce stress changes in the solid Earth that modulate seismicity and promote failure on upper-crustal faults. Here we quantify and review these effects and how they combine with tectonic loading to influence faulting in the southeast, St. Elias and southwest regions of mainland Alaska

Jeanne Sauber↗
NASA NTRSDate not supplied

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↗
NASA NTRS2022

Geologically Recent Areas as One Key Target for Identifying Active Volcanism on Venus

The recently selected NASA VERITAS and DAVINCI missions, the ESA EnVision, the Roscosmos Venera-D will open a new era in the exploration of Venus. One of the key targets of the future orbiting and in-situ investigations of Venus is the identification of volcanically active areas on the planet. The study of the areas characterized by recent or ongoing volcano-tectonic activity can inform us on how volcanism and tectonism are currently evolving on Venus. Following this key target, the manuscript by Brossier et al. (2022) (https://doi.org/10.1029/2022GL099765) extends the successful approach and methodology used by previous works to Ganis Chasma in Atla Regio. We comment here on the main results of the manuscript published by Brossier et al. (2022) (https://doi.org/10.1029/2022GL099765) and discuss the important implications of their work for the future orbiting and in-situ investigations of Venus. Their results add further lines of evidence indicating possibly recent volcanism on Venus.

Solar system↗
NASA NTRS2024

The Analogs for VENus’ GEologically Recent Surfaces (AVENGERS) Initiative: Updates and New Target Areas

Several missions to Venus have been recently selected for launch, opening a new era for the exploration of the planet. One of the key questions that future missions need to address is the rate and style of present-day volcanic activity on Venus. To this regard, an important target on Venus is certainly represented by the young topographic rises, which can be interpreted as the surface expression of underlying mantle plumes. These areas can be considered as the geologically youngest regions of Venus, being characterized by recent volcanic and tectonic activity. Studying areas of active volcanism and tectonism on Venus is crucial as it can reveal clues to the geologic past of the planet, as well as provide information about the volatile content of its interior and about the formation of its dense atmosphere. The “Analogs for VENus’ GEologically Recent Surfaces” (AVENGERS) initiative aims to select and analyze a number of terrestrial analog sites for the comparative study of recent and possibly ongoing volcanic activity on Venus. In addition to its scientific importance, the AVENGERS initiative acts as a bridge for international scientific collaboration, including selected mission teams.

P D'Incecco↗
NASA NTRSDate not supplied

Stress-Activated Positive Holes (O− in a Matrix of O2–) Cause DNA Damage in Surface-Dwelling Organisms: Unveiling Mutation-Induced Secrets of Nature

Peroxy defects consist of pairs of tightly bonded oxygen anions in the –1 valence state such as in O3X/OO\YO3 with X, Y = Si4+, Al3+ etc. They commonly occur in igneous, metamorphic and many sedimentary rocks. When such rocks are stressed by tectonic forces, peroxy defects break up, releasing highly mobile electronic charge carriers: defect electrons in the O2– sublattice, i.e. unbound O–, known as “positive holes”, h•. The h• can flow out of stressed rock volumes, spreading far and wide, causing electric currents and electrochemical reactions. This study explores how the h• impact the electron flow in the electron transport chain (ETC) of organisms on the surface of rocks such as gabbro and granite. We found that, by forming hydroxyl radicals and superoxide anions, the h• disrupt the in vivo coordination of reduction-oxidation reactions that are essential for the timing of the redox cycle. Our observations show that stress activation of h• delays the sprouting of certain plant seeds and impedes the growth of yeast cultures, Saccharomyces cerevisiae. The h• induce mutations and affect plant development as evidenced by reduced stem length and leaf size. At the same time, the h• serve as a source of abiotic oxidation, capable of forming various organic compounds in situ. Through the generation of radical species that create new carbon-carbon bonds the h• facilitate the abiotic synthesis of hydrocarbons and other organic molecules essential to life, including porphyrins. Our findings highlight the intricate interplay between positive holes, redox timing, and biological processes, revealing their significant role in influencing the growth and development of organisms in tectonically stressed crustal environments. Understanding these effects enhances our broader comprehension of redox biology and the influence of environmental factors on cellular development in natural settings.

astrobiology↗
NASA NTRS1994

(abstract) GPS Monitoring of Crustal Deformation and the Earthquake Cycle in Costa Rica

This paper will discuss the objectives, approach, and anticipated results of a study of earthquakes in Costa Rica. GPS measurements will be taken and field surveys will be made. Assessments of seismic strain accumulation and post-seismic deformation will be made in an effort to understand the effect these processes have on regional tectonic models.

tectonics↗
NASA NTRS2005

Preliminary investigation of Zagros thrust-fold-belt deformation using SAR interferometry

Most of the Zagros deformation resulting from the convergence of Arabia and Eurasia takes place in the Southeast Zagros. To apply the SAR interferometry geodetic technique, a few ERS 1 & 2 satellite images were used to map this continuing deformation proven by GPS. Interferograms over 7 years show surprisingly high coherence. The unwrapped phases display a high correlation with topography reflecting atmospheric noise in addition to the desired tectonic signal. We estimate two simple linear trends and remove them from interferograms. The preliminary results show local uplift rates with a likely minimum of 1-2 mm/yr. These early crude results will be tested by more data in project No. 3174.

tectonics↗
NASA NTRS2014

Antarctic Analog for Dilational Bands on Europa

Europa's surface shows signs of extension, which is revealed as lithospheric dilation expressed along ridges, dilational bands and ridged bands. Ridges, the most common tectonic feature on Europa, comprise a central crack flanked by two raised banks a few hundred meters high on each side. Together these three classes may represent a continuum of formation. In Tufts' Dilational Model ridge formation is dominated by daily tidal cycling of a crack, which can be superimposed with regional secular dilation. The two sources of dilation can combine to form the various band morphologies observed. New GPS data along a rift on the Ross Ice Shelf, Antarctica is a suitable Earth analog to test the framework of Tufts' Dilational Model. As predicted by Tufts' Dilational Model, tensile failures in the Ross Ice Shelf exhibit secular dilation, upon which a tidal signal can be seen. From this analog we conclude that Tufts' Dilational Model for Europan ridges and bands may be credible and that the secular dilation is most likely from a regional source and not tidally driven.

Tectonics↗
NASA NTRS2014

The Interior and Orbital Evolution of Charon as Preserved in Its Geologic Record

Pluto and its largest satellite, Charon, currently orbit in a mutually synchronous state; both bodies continuously show the same face to one another. This orbital configuration is a natural end-state for bodies that have undergone tidal dissipation. In order to achieve this state, both bodies would have experienced tidal heating and stress, with the extent of tidal activity controlled by the orbital evolution of Pluto and Charon and by the interior structure and rheology of each body. As the secondary, Charon would have experienced a larger tidal response than Pluto, which may have manifested as observable tectonism. Unfortunately, there are few constraints on the interiors of Pluto and Charon. In addition, the pathway by which Charon came to occupy its present orbital state is uncertain. If Charon's orbit experienced a high-eccentricity phase, as suggested by some orbital evolution models, tidal effects would have likely been more significant. Therefore, we determine the conditions under which Charon could have experienced tidally-driven geologic activity and the extent to which upcoming New Horizons spacecraft observations could be used to constrain Charon's internal structure and orbital evolution. Using plausible interior structure models that include an ocean layer, we find that tidally-driven tensile fractures would likely have formed on Charon if its eccentricity were on the order of 0.01, especially if Charon were orbiting closer to Pluto than at present. Such fractures could display a variety of azimuths near the equator and near the poles, with the range of azimuths in a given region dependent on longitude; east-west-trending fractures should dominate at mid-latitudes. The fracture patterns we predict indicate that Charon's surface geology could provide constraints on the thickness and viscosity of Charon's ice shell at the time of fracture formation.

Tectonics↗
NASA NTRS2023

The Nature of Quaternary Climate Change

Dynamic interactions between atmosphere, hydrosphere, lithosphere, and biosphere, driven by solar energy and modulated by atmospheric greenhouse gasses, volcanism, and plate tectonics produce substantial variations in Earth's climate over geologic time. Major Quaternary drivers of climate change include variations in Earth's orbital cycles, global temperature, natural atmospheric greenhouse gasses, and continental ice mass. Multiple abrupt climate perturbations with onsets of a century to decades have also occurred. Since the 1970s, geologically unprecedented rising levels of anthropogenic greenhouse gasses from fossil fuel combustion, industry, and agriculture have become the dominant contributors to rising global temperature, glacier and ice sheet losses, and sea level rise.

Solar variability↗
NASA NTRS1970

Phase change instability in the mantle

Earth upper mantle phase change instability, discussing temperature gradient, transformation influence on fluid, olivine-spinel phase flow patterns and tectonics

Oxburgh, E. R.↗