1,721,077 research outputs found
The GIS data of the spectral parameter maps of Vesta from NASA/Dawn VIR mapping spectrometer
No full textThe 4 global maps of pyroxene-related spectral parameters derived from data coming from the VIR mapping spectrometer onboard NASA/Dawn acqusition campaing at Vesta
The GIS data of the spectral parameter maps of Vesta from NASA/Dawn VIR mapping spectrometer
No full textThe 4 global maps of pyroxene-related spectral parameters derived from data coming from the VIR mapping spectrometer onboard NASA/Dawn acqusition campaing at Vesta
The ScanMars Subsurface Radar Sounding Experiment on AMADEE-18
Full text linkTerrestrial simulations for crewed missions are critically important for testing technologies and improving methods and procedures for future robotic and human planetary exploration. In February 2018, AMADEE-18 simulated a mission to Mars in the Dhofar region of Oman. During the mission, a field crew coordinated by the Österreichisches Weltraum Forum (OeWF) accomplished several experiments in the fields of astrobiology, space physiology and medicine, geology, and geophysics. Within the scientific payload of AMADEE-18, ScanMars provided geophysical radar imaging of the subsurface at the simulated landing site and was operated by analog astronauts wearing spacesuits during extra-vehicular activities. The analog astronauts were trained to operate a ground-penetrating radar instrument that transmits and then collects radio waves carrying information about the geological setting of the first few meters of the subsurface. The data presented in this work show signal returns from structures down to 4 m depth, associated with the geology of the investigated rocks. Integrating radar data and the analog astronauts' observations of the geology at the surface, it was possible to identify the contact between shallow sediments and bedrock, the local occurrence of conductive soils, and the presence of pebbly materials in the shallow subsurface, which together describe the geology of recent loose sediments overlying an older deformed bedrock. The results obtained by ScanMars confirm that subsurface radar sounding at martian landing sites is key for the geological characterization at shallow depths. The geologic model of the subsurface can be used as the basis for reconstructing palaeoenvironments and paleo-habitats, thus assisting scientific investigations looking for traces of present or past life on the Red Planet.
The ScanMars radar was operated following procedures and training developed before the mission.
Approximately 2000 m of radar data profiles have been acquired during the analog mission.
Combining the results for ScanMars, orbital remote sensing data, and first-person observation in the field while wearing spacesuits (analog astronauts), it was possible to generate a geological model at the AMADEE-18 study site.</sec
2D and 3D Ground Penetrating Radar (GPR) can improve paleoseismological researches: an example from the Mt. Vettore Fault (Central Appennines, Italy)
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A multidisciplinary approach for the study of an ancient drainage tunnel: preliminary results
No full textA multidisciplinary approach is being used to investigate an ancient draining tunnel, about 70 m long, built in the roman age, used to supply drinkable water to the city of Spellum (now Spello, Central Italy). The surface geological and structural information of the site were integrated with the data acquired by Ground Penetrating Radar (GPR) extending surficial observations to the subsurface. In the surveyed area the outcrops are made up by the marly Scaglia Variegata and carbonatic Scaglia Rossa Formations, belonging to the Umbria Sequence. As it is well known, the GPR is a non-destructive geophysical tool that provides several advantages over other methods as it can provide continuous, high-resolution data allowing rapid field surveys where the required investigation depth is up to 20 m depth; however in the presence of freactured rocks, water and artificial manufacts many problems are still open. The initial acquisition of structural and stratigraphic measurements on the studied area allowed to plan and set up the radar survey to improve the following phase of interpretation of the geophysical data. The combined analysis of structural, stratigraphic and geophysical data allowed to map at high resolution the underground stratigraphic sequence around the drainage tunnel. It was also possible to detect the water table, and its spatial relationship with the tunnel. The results of this study, in spite of being still in an embryonic state, indicate that the approach can give interesting results: it will define with good details the geologic setting of the site and the local infiltration pattern, in order to provide all the necessary information to protect the historical resource
3D GPR investigation along Mt. Vettore Fault (Pian Grande/Castelluccio di Norcia-Umbria
No full textPaleoseismology investigates geologic structures and sediments for the evidence of ancient seismic events.
Shallow Quaternary sediments are commonly studied using several geologic and geophysical techniques.
Ground penetrating radar (GPR) uses high-frequency electromagnetic impulses to probe the underground,
resulting in an high resolution imaging of the shallow subsurface. The acquisition of GPR data over a dense
enough grid, allow to study geologic structures in their actual three dimensional geometric setting.
We are presenting a GPR survey made across the Mt. Vettore fault, in the Central Apennines (Italy), in order
to enrich informations on this silent fault obtained previously by direct paleoseismologic analysis made by
trenching the fault zone.
We first localized the fault with some reconnaissance profiles across a small scarp over a Late PleistoceneHolocene alluvial fan, then we estimated the dielectric properties of the medium with two velocity profiles.
After the preliminary measurements, we acquired radar data over a 20x20 m survey grid opportunely spaced
to avoid signal aliasing. After processing, this data furnishes a detailed three dimensional image of the SSENNO fault, so that the both the geometric and compositional features can be studied. We detected the main
trend of the fault and also two main radar facies have been identified, corresponding to the sedimentary units
at the hangingwall and footwall of the main fault strand.
GPR showed itself to be an effective method to extend bi-dimensional data to a three dimensional
environment. In particular in this work, direct trench observation from previous studies and radar data
showed their mutual usefulness, and this confirm the Ground Penetrating Radar to be a particularly useful
tool for the paleoseismologic studies
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
3-D GPR data analysis for high-resolution imaging of shallow subsurface faults: The Mt Vettore case study (Central Apennines, Italy)
No full textThe activation of Late Quaternary faults in the Central Apennines (Italy) could generate earthquakes
with magnitude of about 6.5, and the Monte Vettore fault system probably belongs to
the same category of seismogenetic faults. Such structure has been defined ‘silent’, because
of its geological and geomorphological evidences of past activation, but the absence of historical
records in the seismic catalogues to be associated with its activation. The ‘Piano di
Castelluccio’ intramountain basin, resulting from the Quaternary activity of normal faults, is
characterized by a secondary fault strand highlighted by a NW–SE fault scarp: it has been
already studied through palaeoseismological trenches, which highlighted evidences of Quaternary
shallow faulting due to strong earthquakes, and through a 2-D ground penetrating
radar (GPR) survey, showing the first geophysical signature of faulting for this site. Within
the same place, a 3-D GPR volume over a 20 × 20 m area has been collected. The collection
of radar echoes in three dimensions allows to map both the vertical and lateral continuity
of shallow geometries of the fault zone (Fz), imaging features with high resolution, ranging
from few metres to centimetres and therefore imaging also local variations at the microscale.
Several geophysical markers of faulting, already highlighted on this site, have been taken as
reference to plan the 3-D survey. In this paper, we provide the first 3-D subsurface imaging of
an active shallow fault belonging to the Umbria-Marche Apennine highlighting the subsurface
fault geometry and the stratigraphic sequence up to a depth of about 5 m. From our data,
geophysical faulting signatures are clearly visible in three dimensions: diffraction hyperbolas,
truncations of layers, local attenuated zones and varying dip of the layers have been detected
within the Fz. The interpretation of the 3-D data set provided qualitative and quantitative
geological information in addition to the fault location, like its geometry, boundaries and an
estimation of the fault throw
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