1,720,994 research outputs found
Cartografia geomorfologico-applicativa per un'area campione delle Marche meridionali.
No full textLa carta (scala 1:10.000) si riferisce ad una ristretta area del bacino del Tenna (Marche). Vi vengono rappresentati i fondamentali lineamenti geomorfologici e lito-tecnici del substrato geologico e dei depositi continentali. La finalità del lavoro è quella di mettere a punto una legenda di rappresentazione cartografica di tali elementi di spiccato interesse applicativo
Shallow electrical and seismic imaging of the Pineto Mud Volcano (Central Italy)
No full textShallow underground electrical and seismic imaging was undertaken at the Pineto (Central Italy)
Mud Volcano site using 2D-3D electrical resistivity tomography (ERT) and 2D reflection seismic
surveys. This mud volcano or mud lump (known by the local population as “Cenerone Mud Volcano”)
appears as a dome of about 15x10 m in size. The height is approximately 2 m with a crater 2.5 m of
diameter where emission of fluids and solids (cold brine, mud, gas) occurs. Upper Pliocene-Lower
Pleistocene foredeep pelitic deposits (clays with silty-sandy levels) overlain by clayey-silty deposits
outcrop in the area. Below the Middle Pliocene deposits, a NNW-SSE anticline which runs
approximately 2 kilometers to the WSW of the site represents the main element of the compressional
tecnonic setting. Ditchs and streams in the area run along fault systems that are oriented NW-SE and
NE-SW. These could be related to the upward migration of deep mud fluids. 2D-ERT results were used
to determine the geometry of the high conductivity body related to the uprising of mud fluids and
detecting changes in deposits. Detailed geometry reconstruction of the shallow upward migration of mud
fluids was obtained by using 3D-ERT. A shear wave reflection seismic survey was undertaken to
determine stratigraphic limits and to assess the occurrence of fractured zones along which mud fluids
could migrate towards the surface. The survey results revealed that the uprising of deep fluids doesn’t
occur exactly below the mud volcano at present. Instead, a high conductivity body occurs at
approximately 60 m to the ENE, within a fractured zone in the undercompacted clays. The probable
occurrence of a high permeability layer approximately between 20 m and 30 m below ground level,
confined by clay layers, gives rise to an overpressured mud reservoir. This is the source of mud fluids
which flow to the surface through a mud conduit that appears nearly horizontal at depth and then
inclined towards the surface up to the mud volcano crater
Una legenda per la cartografia degli elementi geologici e geomorfologici di pericolosità sismica.
No full textApplication of 1D-2D electrical resistivity surveys to the identification and investigation of shallow paleochannels in the Chamelecòn Valley (Honduras)
No full textIl lavoro confronta i risultati ottenuti dall’utilizzo di due differenti metodi di prospezione elettrica, nell’ambito di uno studio finalizzato alla ricerca e caratterizzazione di paleoalvei presenti in due siti opportunamente selezionati lungo la valle del Rio Chamelecòn (Honduras). L’applicazione di sondaggi elettrici verticali (1D) ha permesso di determinare la presenza di paleoalvei; la caratterizzazione geometrica e litologica di questi è stata invece ottenuta mediante applicazione di indagini di tomografia elettrica 2D (ERT)
Carta degli elementi geologici di pericolosità sismica. Bacino del Tenna (Marche) tra Santa Vittoria in Matenano e Monte San Martino.
No full textUtilizzazione della metodologia GPR per la ricerca di mineralizzazioni di quarzo ametista nei basalti mesozoici della Repubblica Oriental del Uruguay
No full textNew insights on advanced redox zonation of aquifers using multivariate geostatistics: the San Pedro Sula case study
No full textThe incorrect land use and wastewater management represent anthropogenic pressures on the environment,
which can create heavy euthrophication conditions in surface-water. When surface-water/groundwater
relationships exist, the organic matter produced in the euthrophicated streams can be transferred into the aquifer,
triggering redox processes (i.e. Terminal Electron Accepting Processes, TEAPs). These hydrogeochemical
processes provoke severe groundwater quality modifications (e.g. Mn and Fe solubilization), that complicate
its exploitation and management. The definition of the redox zonation of aquifers represents an effective tool
for the identification of the pollution sources and for the conceptual model refinement, when remediation
strategies and groundwater management plans need to be implemented.
The study area is the San Pedro Sula aquifer (north-western Honduras), which is a multi-layer alluvial
aquifer characterized by well-known surface-water/groundwater interactions and by heavy euthrophicated
streams. Here, high concentrations of Mn and Fe have been found in the aquifer (Di Curzio et al., 2016).
Although the redox processes are dynamic reactions, the redox zonation is generally aimed to identify
homogenous zones within an aquifer characterized by a predominant TEAP (McMahon & Chapelle, 2008).
To overcome this methodological approach, the Multi-Collocated Factorial Kriging (MCFK) (Sollitto et
al., 2010) has been applied to chemico-physical parameters and analytes, diagnostic of the redox processes
(i.e. temperature, pH, turbidity, Mn, Fe, NO3, NH4, PO4). These parameters have been measured in 93 wells,
both in the wet and dry season. In addition, the distance from the surface-water has been selected as an auxiliary
variable, essential to perform the MCFK, because the eutrophicated streams have been considered one of the
pollution sources.
The MCFK results show a short range variability, highlighting a strong relation between Mn concentrations
and redox processes, due to the organic matter transfer from heavy polluted surface-water to the aquifer.
Simultaneously, the relation between Fe and turbidity can be due to a fine colloidal phase, developed when
different redox conditions of groundwater mix up in the wells. At a wider range, Fe seems to be related with
redox processes, near the other pollution source detected in the northern San Pedro Sula alluvial plain
Site resonance frequency assessment through dynamic load testing (DLT): early results of a test carried out in the experimental site of Fivizzano (MS, Italy)
No full textThe assessment of the local seismic response is one of the fundamental phases when it comes to
defining the levels of seismic hazard at a detailed scale. These are typically known as seismic zonation
studies. The estimation of the site specific resonance frequency is a parameter of relevant interest within
such studies as it is associated with the maximum seismic amplification which has to be related to the
frequency of resonance of buildings. The ambient noise based methods and other experimental methods
for measuring this parameter are not always applicable because they are strongly influenced by contrasts
of impedence and by lateral subsurface heterogeneities. Furthermore, they sometimes present limits that
are not always clearly known. On the other hand, the classic analytical approach that makes use of
integrated and multidisciplinary investigation methods, which estimate the local amplification
parameters, mainly in terms of amplification factors and response spectrums, currently presents
uncertainties and limitations. These are essentially associated with the difficulty of modelling the
mechanisms of propagation of the seismic waves within a 3D system. The authors of this paper propose
the experimental measurement of the site resonance frequency by means of Dynamic Load Testing
(DLT). This is done by presenting the operative procedures, the data processing and the results obtained
from a test undertaken at the experimental site of Fivizzano (Massa-Carrara, Italy) where a detailed
study of the local seismic response was also undertaken. The test involved the delivery of sinusoidal
forces with maximum amplitude of 20 kN and a range of frequencies between 0 and 15 Hz by means of
an electro-mechanical generator. Simultaneous seismic monitoring was undertaken through a
multichannel acquisition system. Velocimeters were placed on the ground and in a nearby strategic
building. The measured frequency of resonance was compared to the predicted value obtained from
empirical-analytical solutions and application of horizontal to vertical spectral ratios (HVSR) method
and to the value measured by a seismic station equiped with two coupled accelerometers, one at the
surface and one at depth; these sensors allowed an accurate analysis of the effects of the drift deposits
overlying the bedrock, that is the transfer function of the stratigraphic column at the site
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
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