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  • Open access
  • 119 Reads
GEOLOGICAL ASTROIKOS

Abstract:

To establish a human colony in a planetary body different from the terrestrial one, will entail to join those factors that can favour the good development of life in that place. However, which of these possible parameters can be categorized as essential when referring to the creation of a shelter for a long stay?

Human beings, willing to abandon their natural environment in order to open new extra-terrestrial settlements for present and future generations, have to stay long hours cloistered in a volume built in a quite hostile environment a priori. They deserve to find a habitat which not only makes them feel protected, with the tranquillity and comfort that entails, but also provides an environment capable to transmit desire to live and be.

Astroikos. Term whose suffix Oikos ("house", in Greek) defines in classical antiquity the set of goods and people that constituted the basic unit of society, allows us to identify the new planetary habitat as the possible refuge of a multidisciplinary team of astronauts aiming at colonizing other worlds. This would be based on four fundamental pillars:

1. The humanization of Space Architecture.

2. The possibility of the use of indigenous materials, resources and natural geological structures, as well as the recycling of elements of space vehicles.

3. Self-construction.

4. Security.

  • Open access
  • 67 Reads
River color monitoring using optical satellite data

Knowledge of inland water quality and riverine inputs to oceans is fundamental for water management, environmental monitoring and for the definition of policies and planning strategies related to the sustainable use of rivers. While European Union directives aim at the conservation of inland water resources, the ground operational monitoring network is often inadequate. Rivers monitoring using Remote Sensing may complement in-situ measurements supplying continuous spatially explicit representation of parameters related to water quality and solid transport, even if the high frequency dynamics of water parameters could be not catched due to limited satellite revisit time.
Sentinel-2 and Landsat 8 satellites, equipped with MSI and OLI optical sensors whose spectral bands allow to perform a more accurate atmospheric correction, allow to develop methodologies for monitoring river color from space thanks to high spatial resolution and short revisit time.
This study present a processing chain developed to monitor water constituents in rivers using high resolution satellite images. Multitemporal analysis of Chl-a and Total Suspended Matter (TSM) bio-geophysical variables was performed for the case study of Po river (Italy) for the year 2017. Quantitative estimation of water constituents, retrieved from both Sentinel-2 and Landsat 8 satellite data, using the C2RCC and ACOLITE algorithms, were compared and main outcomes discussed. The developed processing chain can be used to create operational services for river monitoring and represent a major improvement in the identification of spatio-temporal dynamics, like solid transport, in riverine systems.

  • Open access
  • 336 Reads
An overview of radiological hazards related to geological external gamma radiation in outdoor environments
Published: 13 June 2018 by MDPI AG in 1st International Electronic Conference on Geosciences session Medical Geology

Natural geologic bodies (rocks and derived soils or sediments), as well as building materials prepared from them can constitute an important source of ionizing radiation, mainly due to the presence of uranium, thorium and potassium radionuclides in minerals. Studies on the possible health effects of such radiation have been mostly dedicated to assessing radiation doses in indoor environments both in terms of Rn concentrations and external gamma radiation (especially in relation to building materials). Radiological hazards assessments considering external gamma radiation need to consider the amount of time of exposition to the radiation source and hence outdoor situations have been less considered. However, there are at least three situations where the potential radiological hazards associated with objects in the outdoor might deserve attention:

- occupancy of structures made of materials with low shielding to gamma radiation;

- spending a high amount of time in the outdoors, especially for workers in activities related to geologic materials extraction such as open mining or quarry (it will be considered that underground mining is a case of indoor environment) and homeless people;

- work areas in terrains with anomalous high contents of radioisotopes, both naturally or as a result of concentration due to human activities (waste deposition) which might also affect other organisms.

In the present work, it is pretended to present an overview of the potential radiological hazards related to external gamma radiation in outdoor situations.

  • Open access
  • 88 Reads
Multi-cycle statistical analysis of laboratory salt weathering tests

Soluble salts are an important pollutant and the main decay agent of stone in the built environment. While their erosive effects are well established, the evolution along time has been much less studied. This temporal aspect is nonetheless frequently very important in an applied perspective when it is necessary to assess whether a given observed decay situation is at equilibrium or will evolve in the sense of further erosion (hence requiring interventions to avoid that kind of evolution). Laboratory tests for assessing the effect of salt weathering are generally based on the final mass variation after a certain number of cycles simulating salt effects (as is indicated in the European Standard EN12370).

While there have been proposals of parameters that consider the results of the cycles (average and extreme values), here it is aimed to present analyses based on the values in different cycles. This will allow to use statistical multivariate tools and since these cycles follow a sequence, it will be possible to evaluate the presence of trends.

These tools will be discussed in the concrete context of three limestone types and it will be shown that this analysis lends a further quantitative and reproducible support and corroboration to the petrological models that have been proposed to explain the answer of these rock types to salt pollution.

  • Open access
  • 40 Reads
Principal Components Analysis (PCA) of Monument Stone Decay by Rainwater: a case study of “Basílica da Estrela” church, Portugal

An extended version of Principal Components Analysis (PCA) of monument stone decay phenomena occurring at “Basilica da Estrela” church, Lisbon, Portugal, is now presented. This one results from previous studies based mainly on a combined application of multivariate statistical analysis and some traditional geochemical tools. The rationale and the general methodological procedures used in PCA will now be presented, as a first step of a stepwise approach to the eigenvector methods of data analysis. With the insights gained we hope to be able to understand and interpret better the results so obtained. PCA, as others “factor analysis” and Eigenvector Methods”, seeks to reveals the presumably simple underlying structure that might exist within a set of multivariate observations. This knowledge could help us to strengthen, supplement and validate the conclusions obtained from the traditional geochemical approach and can be considered a NDT tool for the characterization of alteration of geologic materials in the built environment as it does not involve the extraction of samples from those materials. The data set studied gathers information on seepage water samples collected over three years inside “Basilica da Estrela” (seepage waters derived from rainwater that penetrated and percolate the monument changing its composition through water-rock interactions). Precipitation of some of their dissolved components due saturation and/or evaporation along the monument percolating system contributed also for their final chemical and physical properties. Temperature, pH, electrical conductivity, SiO2 and main ionic species were measured on each sample.

  • Open access
  • 37 Reads
In defense of stamp collecting: the importance of case studies for Geology teaching

The expression “stamp collecting” is commonly used in a derogatory way for study areas that frequently rely on case studies and observations, sometimes resulting of chance, which can be perceived as akin to mere accumulation of facts without value for theories or as being only usable in a inductive perspective. However, even the main opponent of inductivism of the last century, Karl Popper, admitted in his “Realism and the aim of Science” that “some [scientists] may get their ideas by observing, or by repeating observations” (albeit this was put in the same level of getting ideas from smoking or drinking coffee or whisky).

In Geosciences there is a long history of the relevance of case observations that can serve to refute models or as catalizers of ideas, namely for features that cannot be replicated under controlled experimental conditions.

This publication aims to present an overview of examples illustrating how case observations can contribute to Geology teaching, base in the author’s own experience concerning both rock outcrops and stones present in the built environment. The examples presented will concern diverse study areas namely Mineralogy, Geomorphology, Geochemistry, Petrology, Ore deposits, Engineering Geology and Mineral Exploration.

These case observations will be also used to highlight the importance of hypothesis discussion and critical thinking.

  • Open access
  • 52 Reads
Understanding Satellite Image-Based Green Space Distribution for Setting Up Solutions on Effective Urban Environment Management

Urban environments are vulnerable, as there is a change in the surface structure of the land cover. Particularly when natural vegetation cover is converted to construction land, which is covered by impervious surfaces, it increases the accumulation of solar energy. This has led to an increasingly urban environment that is becoming more severe and threatening to affect the quality of life in urban populations. Satellite images are very helpful in determining the distribution of green space. The paper presents the results of analyzing urban land cover for determining green space (GS) distribution for Ho Chi Minh City (HCMC). In 2017, the vegetation land of the old 13 urban districts accounts for only one third of the impervious surface. In contrast, in the area of 6 new urban districts there is a high percentage of urban green space, accounting for nearly twice the proportion of the impervious surface type. This shows that the old inner city area is seriously lacking GS area. Most districts have very low GS index, less than 10 m2/person, some districts even less than 3 m2/person. In the eastern part of the city, only District 9 has the highest GS index, and ensures a good life quality. Since then, the research has provided a number of management solutions to improve and develop the GS area, while enhancing the environment quality and the life quality for the population. The research results contribute to the effective urban management for HCMC.

  • Open access
  • 35 Reads
PROPOSING GEOPRODUCTS FOR LY ​​SON GEOPARK, VIETNAM
Published: 14 June 2018 by MDPI AG in 1st International Electronic Conference on Geosciences session Others

Ly Son district includes two off-shore volcanic islands: Ly Son island (Re isle) and Little island (Bo Bai isle), located in the eastern of Quang Ngai Province, central of Vietnam, covers approximately 9.97 km2of land. Ly Son and surrounding area will be applying to become a Geopark in UNESCO Global Geoparks. The island district is a product of volcanic activity that creates a wide variety of geomorphologyforms: modern marine deposition, marine sediment, basalt flow and volcanic eruptions and other geo-features. As a result of the geosite inventory, together with the assessment of scientific value and additional values ​​(ecology, culture - history, economics, aesthetics), the study was conducted to propose a wide range of geo-products for Ly Son Geopark. The suggested products include: tourist center; interpretation system: introduction, explanation of scientific values ​​and additional values of some geosites: Hang Cau –Chua Hang and Thoi Loi Geosite, To Vo Natural Gate, Bai Tien Geosite – Bo Bai Isle; geo-trail, geo-road, geo-adventure; as well as local products. Geo-products will definitely contribute to support local economic development, appealing tourists and also effectively enhancing the Earth Science education and conservation.

  • Open access
  • 31 Reads
Analysis of 04 years (2002-2005) of laser data on Starlette, Stella and LAGEOS-I/II satellites for stations coordinates and Earth Orientation Parameters (EOP)

The present paper deals with the computation of Laser stations coordinates and Earth Orientation Parameters (EOP) based on measurements of low Earth orbit (LEO) satellites, namely Starlette (STA) and Stella (STL). The orbits of these satellites are less accurate than those of the LAGEOS satellites (usually used for an accurate calculation), because they are more affected by gravitational and non-gravitational forces. The objective is to achieve a good quality on the geodetic products by inter-satellite combination of Low and High satellites data. The orbit computation of the different satellites is performed by the GINS software (GRGS/France) and the laser data processing is carried out by the MATLO software (IGN, OCA/France), considering the use of gravity field model (Eigen_Grace-03s) of GRACE satellite, over a period of 04 years (between January 2002 and December 2005). The results in terms of time series are projected onto the reference frame ITRF2000 by the CATREF software (IGN/France), where the Helmert transformation parameters are obtained. Two solutions were compared: LA1 + LA2 (LL) and LA1 + LA2 + STL + STA (LLSS), in terms of quality time series of residual positions of stations, EOP and Geocentre variations. The results show that the data obtained from LEO satellites such as Starlette and Stella can be successfully used in the accurate determination of Laser geodetic products.

  • Open access
  • 43 Reads
Deformation Analysis Of The Seismic And Post-Seismic Cheliff (Algeria) Geodetic Network Using 2d Elastic Finite Element Method (FEM)

The region of Cheliff, located at the North West of Algeria, is one of an exceptional interest for crustal motion study which is due to seismic activity. Usually, in the deformation analysis of geodetic networks, there are two conventional methods for estimating the movements of an area of ​​study: displacement vectors and strain tensors. However, the evaluation and representation of the deformation depend on the priori reference system and on the configuration of chosen elements that constitute the entire network. These constraints make difficult the interpretation of the results. Through this present paper, a solution based on the finite element method (FEM) is proposed to refine the estimation and the representation of the deformation of geodetic networks. In this context, a study of the deformation is carried out to analyze the horizontal motion of the Cheliff geodetic network due to the famous earthquake of October 10, 1980 (Ms = 7.3), based on two-dimensional elastic finite element model. This network was observed by classical triangulation in 1976 (by INCT) and in 1981 (by CRAAG). The different results are illustrated in terms of displacement vectors, strain and stress tensors where the estimated deformation is interpreted according to previous geophysical studies. They revealed a compressive phenomenon of Cheliff area, in the NNW-SSE orientation, due to the convergence of the African and Eurasian tectonic plates, and to a block rotation phenomenon, at the SE and NW parts of the fault, in a retrograde direction. The study was extended to the post-seismic geodetic network observed between June1990 and April 1992 by CRAAG. The network was established by distance measurements, with 12 monitoring points distributed along the reverse fault. The results obtained show a post seismic meaningful deformation, in the fault central segment, characterized by global NW-SE direction of strain tensors in agreement with ground data.

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