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Geosciences, Volume 10, Issue 6 (June 2020) – 44 articles

Cover Story (view full-size image): The cover of Issue 6 of Geosciences is a photo of the Seyakha Crater area. This сrater was formed in the Russian Arctic river channel on the Yamal Peninsula as a result of powerful blowout, self-ignition, and explosion of gas. Before the explosion, a perennial frost heave mound of gas-dynamic genesis existed at the location of the crater. This photo was taken by Igor Bogoyavlensky from an unmanned aerial vehicle, drone “DJI Mavic Pro” (DJI, Shenzhen, China), from a height of 250 m. View this paper
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Article
Geology of the Epicentral Area of the November 23, 1980 Earthquake (Irpinia, Italy): New Stratigraphical, Structural and Petrological Constrains
Geosciences 2020, 10(6), 247; https://doi.org/10.3390/geosciences10060247 - 25 Jun 2020
Cited by 10 | Viewed by 1555
Abstract
The geology of the epicentral area of the 1980 earthquake (Irpinia-Lucania, Italy) is described with new stratigraphic, petrographic and structural data. Subsurface geological data have been collected during the studies for the excavation works of the Pavoncelli bis hydraulic tunnel, developing between Caposele [...] Read more.
The geology of the epicentral area of the 1980 earthquake (Irpinia-Lucania, Italy) is described with new stratigraphic, petrographic and structural data. Subsurface geological data have been collected during the studies for the excavation works of the Pavoncelli bis hydraulic tunnel, developing between Caposele and Conza della Campania in an area that was highly damaged during 1980 earthquake. Our approach includes geological, stratigraphic, structural studies, and petrological analyses of rock samples collected along the tunnel profile and in outcropping sections. Stratigraphic studies and detailed geological and structural mapping were carried out in about 200 km2 wide area. The main units cropping out have been studied and correlated in order to document the effects of tectonic changes during the orogenic evolution on the foreland basin systems and the sandstone detrital modes in this sector of the southern Apennines. The multi-disciplinary and updated datasets have allowed getting new insights on the tectono-stratigraphic evolution and stratigraphic architecture of the southern Apennines foreland basin system and on the structural and stratigraphic relations of Apennines tectonic units and timing of their kinematic evolution. They also allowed to better understand the relationships between internal and external basin units within the Apennine thrust belt and its tectonic evolution. Full article
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Article
The 1730 Great Metropolitan Chile Earthquake and Tsunami Commemoration: Joint Efforts to Increase the Country’s Awareness
Geosciences 2020, 10(6), 246; https://doi.org/10.3390/geosciences10060246 - 24 Jun 2020
Cited by 6 | Viewed by 2143
Abstract
On 8 July 1730, a great earthquake struck metropolitan Chile, causing extensive damage 1000 km along the country and focused in Valparaíso. Due to the date of occurrence of this event, large uncertainties about the earthquake’s magnitude have been discussed among the scientific [...] Read more.
On 8 July 1730, a great earthquake struck metropolitan Chile, causing extensive damage 1000 km along the country and focused in Valparaíso. Due to the date of occurrence of this event, large uncertainties about the earthquake’s magnitude have been discussed among the scientific community, and the earthquake and tsunami have remained unknown for most of the population. The purpose of this paper is to describe joint efforts undertaken by organizations, academia, and authorities to rescue the forgotten memory of an event that occurred almost three centuries ago and that may be repeated in the near future. In line with the Sendai Framework, we focus on one of the four priorities for action, which is to understand disaster risk, with the premise that the memory activation and raising awareness can save lives in the future. We designed outreach strategies to communicate this knowledge to the community in a participatory way. The latter involves scientific talks, earthquake simulators, tsunami projection mapping on relief scaled models (mock-up), and a public debate including the participation of academia, politicians, authorities, and the local community. The emulation of such activities and the constant work of regional and national authorities, academia, and non-governmental organizations dealing with risk mitigation encourage involving the community to build safer cities against the tsunami hazard. Full article
(This article belongs to the Special Issue Advances in tsunami science towards tsunami threat reduction)
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Article
Ground Surface Deformation Detection in Complex Landslide Area—Bobonaro, Timor-Leste—Using SBAS DInSAR, UAV Photogrammetry, and Field Observations
Geosciences 2020, 10(6), 245; https://doi.org/10.3390/geosciences10060245 - 24 Jun 2020
Cited by 5 | Viewed by 3375
Abstract
During the past 10 years, Timor-Leste has concentrated all its efforts on infrastructure development. However, it has not achieved enough due to unexpected ground deformation in mountainous areas that is seriously affecting road constructions, etc. In order to design roads and other infrastructure [...] Read more.
During the past 10 years, Timor-Leste has concentrated all its efforts on infrastructure development. However, it has not achieved enough due to unexpected ground deformation in mountainous areas that is seriously affecting road constructions, etc. In order to design roads and other infrastructure under such difficult conditions, it is important to know the present and future ground conditions. Continuous monitoring is a significant methods of detecting ground deformation and providing essential information to realize an effective design. The problem arises of “How can ground deformation be monitored in extensive areas, which are generally located in mountain areas that are difficult to access?” Differential Interferometry Synthetic Aperture Radar (DInSAR) has recently been applied to monitor displacement in extensive areas. In addition, Unmanned Aerial Vehicle (UAV) photogrammetry is useful for detecting the deformation in detail. Both methods are advantageous in that they do not require any sensors. Therefore, the combination of DInSAR and UAV photogrammetry is one of the solutions for monitoring the ground deformation in Timor-Leste. In this paper, DInSAR and UAV photogrammetry are applied to unstable ground in the Bobonaro region of Timor-Leste to find the recent ground deformation, since 2007, due to earthquakes and hard rainfall events. It is found that DInSAR is useful for screening usual and unusual ground behavior and that UAV photogrammetry is flexible to use and can detect displacements with cm accuracy after the DInSAR screening. Full article
(This article belongs to the Special Issue Scientific Assessment of Recent Natural Hazard Events)
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Article
Ground-Penetrating Radar Survey for the Study of the Church of Saint Cosma in Helerito (Tagliacozzo, L’Aquila, Italy)
Geosciences 2020, 10(6), 244; https://doi.org/10.3390/geosciences10060244 - 23 Jun 2020
Cited by 1 | Viewed by 913
Abstract
This paper deals with the application of geophysical prospections to the study of the Church of Saint Cosma in Helerito inside the Monastery of Saints Cosma and Damiano (Tagliacozzo, L’Aquila, Italy). The research aimed to verify the presence of buried ancient archaeological structures [...] Read more.
This paper deals with the application of geophysical prospections to the study of the Church of Saint Cosma in Helerito inside the Monastery of Saints Cosma and Damiano (Tagliacozzo, L’Aquila, Italy). The research aimed to verify the presence of buried ancient archaeological structures of a construction phase older than the current building. Thus, a grid of ground-penetrating radar (GPR) profiles was carried out inside the building in the available spaces using a radar unit equipped with a multi-frequency antenna of 200–600 MHz. The analysis of 2D radargrams and horizontal slices relative to different temporal ranges led to the identification of significant regular patterns of the amplitude of the electromagnetic signals. The results suggest the presence of a buried structure below the analyzed surface. Full article
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Review
Building Resilient Urban Communities: The Case Study of Setubal Municipality, Portugal
by , , and
Geosciences 2020, 10(6), 243; https://doi.org/10.3390/geosciences10060243 - 23 Jun 2020
Cited by 2 | Viewed by 1700
Abstract
The Sendai Framework for Disaster Risk Reduction provides several guidelines that countries should follow. Still, some scientific papers discussed the limitations, difficulties, and strategies in the implementation of these guidelines. Therefore, the objective of this review is to understand what Setubal has done [...] Read more.
The Sendai Framework for Disaster Risk Reduction provides several guidelines that countries should follow. Still, some scientific papers discussed the limitations, difficulties, and strategies in the implementation of these guidelines. Therefore, the objective of this review is to understand what Setubal has done to cope with disasters, and the practical strategies to mitigate them. To achieve this, several methodological guidelines and Portuguese legal documents were analyzed. The results focus on the top four natural disasters that impacted the study area (landslides, earthquakes, tsunamis, and floods), and the current pandemic of COVID-19. The practical strategies implemented on the territory involve the installation of equipment such as emergency signs and electronic panels that allow the dissemination of information to the communities in real-time. Also, the collaboration with national and international scientists provided new insight to cope with disasters, by bridging the gap between law enforcement agencies, science, first responders, and the practical needs that local stakeholders must solve on the territory. Moreover, Setubal has implemented a variety of practical and innovative measures, and therefore, could be used as a model not only to other Portuguese municipalities but also to other countries. Full article
(This article belongs to the Section Natural Hazards)
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Review
Cadmium Pollution in the Tourism Environment: A Literature Review
Geosciences 2020, 10(6), 242; https://doi.org/10.3390/geosciences10060242 - 22 Jun 2020
Cited by 18 | Viewed by 1723
Abstract
Cadmium is a highly-toxic metal, and, its environmental occurrence and human exposure consequently deserve close attention. The insight into the relationships between cadmium and tourism relations has deepened during the past three decades and the research into this relationship is reviewed. For this [...] Read more.
Cadmium is a highly-toxic metal, and, its environmental occurrence and human exposure consequently deserve close attention. The insight into the relationships between cadmium and tourism relations has deepened during the past three decades and the research into this relationship is reviewed. For this purpose, 83 relevant publications (mainly articles in international journals) were analyzed. It was found that investigation of Cd in the tourism environment took place in all continents (except Antarctica) and has intensified since the mid-2000s; Chinese researchers are the most active contributors. The Cd occurrence in air, living organisms, sediments, soil, suspended particular matter, water, and of the human environment has been studied. It has become clear that tourism contributes to Cd pollution (particularly, by hotel wastewater and increased traffic), and, vice versa, Cd pollution of beaches, coastal waters, food, urban parks, etc. creates risks for tourists and increases human exposure to this toxic metal. Both mechanisms have received equal attention. Examples concern many places worldwide, with the Mediterranean and Central and Eastern Europe as apparently critical regions. Our significantly incomplete knowledge of the relationships between cadmium and tourism must be ascribed to the common oversimplification of these relationships and to the scarcity or even absence of information supplied by the most important tourist destinations. The present review demonstrates that more studies of heavy metals and, particularly, Cd in the tourism environment are needed. Full article
(This article belongs to the Special Issue Perspectives on Environment and Human Health)
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Article
Mechanical Properties and Microstructure of Fibre-Reinforced Clay Blended with By-Product Cementitious Materials
Geosciences 2020, 10(6), 241; https://doi.org/10.3390/geosciences10060241 - 21 Jun 2020
Cited by 10 | Viewed by 1099
Abstract
Clayey soils endure adverse changes in strength and volume due to seasonal changes in moisture content and temperature. It has been well recognised that high cement content has been successfully employed in improving the mechanical properties of clayey soils for geotechnical infrastructural purposes. [...] Read more.
Clayey soils endure adverse changes in strength and volume due to seasonal changes in moisture content and temperature. It has been well recognised that high cement content has been successfully employed in improving the mechanical properties of clayey soils for geotechnical infrastructural purposes. However, the environmental setbacks regarding the use of high cement content in soil reinforcement have necessitated the need for a greener soil reinforcement technique by incorporating industrial by-product materials and synthetic fibres with a reduced amount of cement content in soil-cement mixtures. Therefore, this study presents an experimental study to investigate the mechanical performance of polypropylene and glass fibre-reinforced cement-clay mixtures blended with ground granulated blast slag (GGBS), lime and micro silica for different mix compositions and curing conditions. The unconfined compressive strength, linear expansion and microstructural analysis of the reinforced soils have been studied. The results show that an increase in polypropylene and glass fibre contents caused an increase in unconfined compressive strength but brought on the reduction of linear expansion of the investigated clay from 7.92% to 0.2% at fibre content up to 0.8% for cement-clay mixture reinforced with 5% Portland cement (PC). The use of 0.4–0.8% polypropylene and glass fibre contents in reinforcing cement-clay mixture at 5% cement content causes an increase in unconfined compressive strength (UCS) values above the minimum UCS target value according to American Society for Testing and Materials (ASTM) 4609 after 7 and 14 days curing at 20 °C to 50 °C temperature. Therefore, this new clean production of fibre-reinforced cement-clay mixture blended with industrial by-product materials has great potential for a wide range of applications in subgrade reinforcement. Full article
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Article
Using Remote Sensing Data to Identify Large Bottom Objects: The Case of World War II Shipwreck of General von Steuben
Geosciences 2020, 10(6), 240; https://doi.org/10.3390/geosciences10060240 - 19 Jun 2020
Cited by 5 | Viewed by 1325
Abstract
The seabed of the Baltic Sea is not yet fully searched for and investigated. In 2004 the crew of the Polish Navy hydrographic ship Arctowski discovered a new shipwreck that was not listed in the official underwater objects database nor was it marked [...] Read more.
The seabed of the Baltic Sea is not yet fully searched for and investigated. In 2004 the crew of the Polish Navy hydrographic ship Arctowski discovered a new shipwreck that was not listed in the official underwater objects database nor was it marked on a chart. The identity of a new wreck is most frequently established based on artefacts found in the object by divers as a part of archaeological research, or through underwater inspection with remotely operated vehicle. The aim of this paper is to show how acoustic remote sensing data is used to identify large bottom object without having to go underwater. Bathymetric survey and sonar investigation were conducted over the study area. An appropriate methodology allowed for obtaining high-resolution imagery of the wreck. A review of literature concerning the end of World War II in the Baltic Sea was carried out. Moreover, the author presents a comparative analysis and evaluation of remote sensing data with archival photos, silhouette, and ship characteristics. The proposed approach led to the identification of a new Baltic Sea wreck as the General von Steuben, which was torpedoed in 1945 by soviet submarine. The author’s findings show that state of preservation of the shipwreck, quality data as well as historical records play a key role in establishing the wreck’s identity. Full article
(This article belongs to the Special Issue Marine Habitat Mapping: Selected Papers from "GeoHab 2021")
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Article
Seismic Characteristics and Development of the Upper Jurassic Carbonate Buildups from the Miechów Trough (Southern Poland)
Geosciences 2020, 10(6), 239; https://doi.org/10.3390/geosciences10060239 - 18 Jun 2020
Cited by 1 | Viewed by 1294
Abstract
The presented study is devoted to the subsurface Upper Jurassic carbonate buildups and surrounding stratified inter-buildup deposits in the hitherto less recognized area, in comparison with other parts of the northern Tethyan shelf in Poland and Europe. The study area is located within [...] Read more.
The presented study is devoted to the subsurface Upper Jurassic carbonate buildups and surrounding stratified inter-buildup deposits in the hitherto less recognized area, in comparison with other parts of the northern Tethyan shelf in Poland and Europe. The study area is located within the present-day Miechów Trough, almost entirely covered by thick Cretaceous and younger deposits. This paper shows results of the interpretation of 2D seismic data, calibrated by data from deep wells. Investigation of various elements of the Upper Jurassic carbonate depositional system in the Miechów Trough is supported by seismic facies and attribute analysis. The four distinctive seismic facies—(A) bedded, (B) mound-shaped, (C) contorted-chaotic, and (D) chaotic—were assigned to the main Upper Jurassic sedimentary facies, represented by (1) bedded facies, (2) massive facies (carbonate buildups) and (3) deposits of gravity mass-flows. The results of this study were used to construct a depositional model for the Upper Jurassic succession, that focuses on the initiation, growth and demise of the large carbonate buildups in this part of the basin. This paper also presents the more extensive distribution of the Upper Jurassic carbonate buildups than was previously proposed for the Miechów Trough. Full article
(This article belongs to the Section Geophysics)
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Article
Application of Ground-Penetrating Radar and a Combined Penetrometer–Moisture Probe for Evaluating Spatial Distribution of Soil Moisture and Soil Hardness in Coastal and Inland Windbreaks
Geosciences 2020, 10(6), 238; https://doi.org/10.3390/geosciences10060238 - 18 Jun 2020
Cited by 5 | Viewed by 1133
Abstract
The development of a method to easily investigate the spatial distribution of soil moisture and soil hardness in tree windbreaks is necessary because these windbreaks often decline due to inappropriate soil moisture condition and soil compaction. This research examined the applicability of ground-penetrating [...] Read more.
The development of a method to easily investigate the spatial distribution of soil moisture and soil hardness in tree windbreaks is necessary because these windbreaks often decline due to inappropriate soil moisture condition and soil compaction. This research examined the applicability of ground-penetrating radar (GPR) and a combined penetrometer–moisture probe (CPMP) for evaluating the spatial distribution of soil moisture and soil hardness in four windbreaks with different soil characteristics. A GPR-reflecting interface was observed at a less permeable layer in a coastal windbreak and at a depth affected by soil compaction in an inland windbreak with andosol. The spatial distribution of the groundwater table could also be evaluated by examining the attenuation of GPR reflection in a coastal windbreak. In contrast, GPR was not applicable in an inland windbreak with peat because of high soil water content near the soil surface. The CPMP could detect vertical distributions of soil hardness and soil water content regardless of soil type. The CPMP was useful for interpreting GPR profiles, and GPR was useful for interpolating the information about the horizontal distribution of soil moisture and soil hardness between survey points made with the CPMP. Thus, the combination of GPR and a CPMP is ideal for examining the two-dimensional spatial distribution of soil moisture and soil hardness at windbreaks with soils for which both methods are applicable. Full article
(This article belongs to the Special Issue Modern Surveying and Geophysical Methods for Soil and Rock)
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Article
Nature Does the Averaging—In-Situ Produced 10Be, 21Ne, and 26Al in a Very Young River Terrace
Geosciences 2020, 10(6), 237; https://doi.org/10.3390/geosciences10060237 - 18 Jun 2020
Cited by 4 | Viewed by 1120
Abstract
The concentrations of long-lived in-situ produced cosmogenic nuclides (10Be, 21Ne, 26Al) in quartz obtained from a very recent (~200 a; based on 14C data on organic material) terrace of the Swakop River in Namibia are nearly constant throughout [...] Read more.
The concentrations of long-lived in-situ produced cosmogenic nuclides (10Be, 21Ne, 26Al) in quartz obtained from a very recent (~200 a; based on 14C data on organic material) terrace of the Swakop River in Namibia are nearly constant throughout a 322 cm-long depth profile. These findings corroborate earlier hypotheses postulating a homogeneous distribution of these nuclides in freshly deposited river terrace sediments. An averaged nuclide concentration is a crucial and generally assumed prerequisite for the determination of numerical ages of old sediments. Full article
(This article belongs to the Section Geochemistry)
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Article
Differential SAR Interferometry Using Sentinel-1 Imagery-Limitations in Monitoring Fast Moving Landslides: The Case Study of Cyprus
Geosciences 2020, 10(6), 236; https://doi.org/10.3390/geosciences10060236 - 18 Jun 2020
Cited by 4 | Viewed by 1441
Abstract
Cyprus, being located on the Mediterranean fault zone, exhibits a unique geodynamic regime since its tectonic evolution is driven by the interaction of the Eurasian and African plate. Besides its seismological interest, many active landslides and slope instabilities in areas of steep topography [...] Read more.
Cyprus, being located on the Mediterranean fault zone, exhibits a unique geodynamic regime since its tectonic evolution is driven by the interaction of the Eurasian and African plate. Besides its seismological interest, many active landslides and slope instabilities in areas of steep topography occur in Cyprus, having substantial impact on the built environment, by posing an imminent threat for entire settlements and critical infrastructure. Moreover, extreme meteorological events occur rarely, like severe rainfall and thunderstorms, that combined with the geological properties in some areas and the seismically stressed ground, can lead to landslides, causing severe damages to critical infrastructure. In the present study, the DInSAR methodology is applied for the detection of two individual landslide events that were triggered by heavy rainfall in Limassol and Paphos Districts in February 2019. Six co-event interferometric Synthetic Aperture Radar (SAR) pairs were used to produce displacement maps in vertical and east-west directions to study the resulting slope deformations. The above are carried out using Sentinel-1 imagery that are freely provided under the Copernicus umbrella. The limitations that arise from the speed and complexity of the deformations under study and the adverse residing meteorological conditions that caused these phenomena are investigated, as found in literature. Indeed, the sparse vegetation at the slopes affected by the landslides, the residing meteorological conditions, the heavy rainfall that triggered the two landslides, and the temporal phase aliasing effect due to the speed of the ground deformation were found to be the main limitations for the application of DInSAR methodology, resulting in the underestimation of the ground deformation that occurred. Full article
(This article belongs to the Section Natural Hazards)
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Article
Long-Lasting Patterns in 3 kHz Electromagnetic Time Series after the ML = 6.6 Earthquake of 2018-10-25 near Zakynthos, Greece
Geosciences 2020, 10(6), 235; https://doi.org/10.3390/geosciences10060235 - 18 Jun 2020
Cited by 5 | Viewed by 986
Abstract
This paper reports one-month 3 kHz EM disturbances recorded at Kardamas, Ilia, Greece after a strong ML=6.6 earthquake occurred on 2018/10/25 near Zakynthos and Ilia. During this period 17 earthquakes occurred with magnitudes ML=4.5 and [...] Read more.
This paper reports one-month 3 kHz EM disturbances recorded at Kardamas, Ilia, Greece after a strong M L = 6.6 earthquake occurred on 2018/10/25 near Zakynthos and Ilia. During this period 17 earthquakes occurred with magnitudes M L = 4.5 and M L = 5.5 and depths between 3 km and 17 km, all near Zakynthos and Ilia. A two-stage, fully computational methodology was applied to the outcomes of five different time-evolving chaos analysis techniques (DFA, fractal dimension analysis through Higuchi, Katz and Sevcik methods and power-law analysis). Via literature-based thresholds, the out-of-threshold results of all chaos analysis methods were located and from these, the common time instances of 13 selected combinations per five, four, three and two methods. Numerous persistent segments were located with DFA exponents between 1.6 α 2.0 , fractal dimensions between 1.4 D 2.0 and power-law exponents between 2.2 β 3.0 . Out of the 17 earthquakes, six earthquakes were jointly matched by 13 selected combinations of five, four, three and two chaos analysis methods, four earthquakes by all combinations of four, three and two, while the remaining seven earthquakes were matched by at least one combination of three methods. All meta-analysis matches are within typical forecast periods. Full article
(This article belongs to the Special Issue Electromagnetic and Radon Pre-earthquake Precursors)
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Editorial
Exploring and Modeling the Magma–Hydrothermal Regime
Geosciences 2020, 10(6), 234; https://doi.org/10.3390/geosciences10060234 - 18 Jun 2020
Cited by 5 | Viewed by 1105
Abstract
This special issue comprises 12 papers from authors in 10 countries with new insights on the close coupling between magma as an energy and fluid source with hydrothermal systems as a primary control of magmatic behavior. Data and interpretation are provided on the [...] Read more.
This special issue comprises 12 papers from authors in 10 countries with new insights on the close coupling between magma as an energy and fluid source with hydrothermal systems as a primary control of magmatic behavior. Data and interpretation are provided on the rise of magma through a hydrothermal system, the relative timing of magmatic and hydrothermal events, the temporal evolution of supercritical aqueous fluids associated with ore formation, the magmatic and meteoric contributions of water to the systems, the big picture for the highly active Krafla Caldera, Iceland, as well as the implications of results from drilling at Krafla concerning the magma–hydrothermal boundary. Some of the more provocative concepts are that magma can intrude a hydrothermal system silently, that coplanar and coeval seismic events signal “magma fracking” beneath active volcanoes, that intrusive accumulations may far outlast volcanism, that arid climate favors formation of large magma chambers, and that even relatively dry rhyolite magma can convect rapidly and so lack a crystallizing mush roof. A shared theme is that hydrothermal and magmatic reservoirs need to be treated as a single system. Full article
(This article belongs to the Special Issue Exploring and Modeling the Magma-Hydrothermal Regime)
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Article
Fractal Dimension Analysis Applied to Soil CO2 Fluxes in Campotosto’s Seismic Area, Central Italy
Geosciences 2020, 10(6), 233; https://doi.org/10.3390/geosciences10060233 - 17 Jun 2020
Cited by 1 | Viewed by 916
Abstract
This article reports fractal dimension analysis applied to soil CO2 fluxes measured in an Italian seismic area. The work was carried out with the use of a calibrated flux chamber unit. The fractal dimension (FD) from isotropic variograms was used as a [...] Read more.
This article reports fractal dimension analysis applied to soil CO2 fluxes measured in an Italian seismic area. The work was carried out with the use of a calibrated flux chamber unit. The fractal dimension (FD) from isotropic variograms was used as a method to understand related scale-dependent phenomena. The aim was to investigate the spatial variability of CO2 flux measurements in four directions (horizontal, vertical, 45° and 135° directions) related to different distances between the measuring points and from a fault. High fractal dimension values were found (2.5 ≤ FD ≤ 3.0). These imply strong anti-persistent behavior near to and far from the fault. Lower fractal dimensions were addressed at longer distances from the fault. Full article
(This article belongs to the Special Issue Electromagnetic and Radon Pre-earthquake Precursors)
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Article
Investigation of Geological Anomalies at Pile Foundation Location in Urban Karst Areas Using Single Borehole Radar
Geosciences 2020, 10(6), 232; https://doi.org/10.3390/geosciences10060232 - 16 Jun 2020
Cited by 3 | Viewed by 1305
Abstract
Karst geological anomalies at pile locations significantly affect the bearing capacity and construction safety of the piles, posing a significant challenge for urbanization. Borehole geophysical methods are required to extend the detection range and identify karst voids that are at pole locations and [...] Read more.
Karst geological anomalies at pile locations significantly affect the bearing capacity and construction safety of the piles, posing a significant challenge for urbanization. Borehole geophysical methods are required to extend the detection range and identify karst voids that are at pole locations and near drilled boreholes. In this paper, we developed a near offset and small diameter single borehole ground penetration radar (GPR) prototype. A signal processing method combining complex signal analysis by Hilbert transform (HT) and medium filtering was suggested to differentiate the weak backscattered wave from borehole background noise. A controlled horizontal borehole experiment was used to demonstrate the applicability of the prototype and the advantages of the signal analysis method prior to application in a real project. The controlled test presented three typical wave events corresponding to a soil–rock interface, rock fractures, and karst voids. Field tests were conducted at a freeway bridge extension project in an urban karst area. Multiple karst voids, sinkholes, rock fractures, and integrated bedrock were identified by analysis of four typical detection scenarios. The remediation of the karst voids and a rotary bored piling with real-time steel casing construction strategy were designed based on the investigation results. The construction feedback demonstrates that single borehole radar detection is effective for the investigation of anomalies at pile locations in urban karst areas. Full article
(This article belongs to the Special Issue Urban Geophysics)
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Article
A Computer Aided Approach for River Styles—Inspired Characterization of Large Basins: A Structured Procedure and Support Tools
Geosciences 2020, 10(6), 231; https://doi.org/10.3390/geosciences10060231 - 15 Jun 2020
Cited by 4 | Viewed by 978
Abstract
This paper presents a systematic procedure for developing a characterization and classification of river reaches inspired by the River Styles Framework, through which insight can be gained about the understanding of river behavior. Our procedure takes advantage of several computer based “tools”, i.e., [...] Read more.
This paper presents a systematic procedure for developing a characterization and classification of river reaches inspired by the River Styles Framework, through which insight can be gained about the understanding of river behavior. Our procedure takes advantage of several computer based “tools”, i.e., algorithms implemented in software packages of various types, from “simple” Excel sheets to sophisticated algorithms in Python language, in general all supported by Geographic Information Systems (GIS). The main potentially useful, existing tools for this specific aim are discussed here, revealing their strengths and weaknesses. New, complementary or alternative tools that have been developed in the project feeding this paper are presented, which can contribute to the scientific community and stakeholders of the topic. The main result of our research is a structured and practical guide (a ToolBox Manual) that can support practitioners and researchers wishing to characterize and classify large rivers, based on the River Styles Framework. The main contribution is that this set of ideas, solutions, and tools, makes this type of exercise significantly more transparent and at the same time much less subjective. Moreover, the procedure is applicable to large systems and does not require more information than that generally available also in developing or emerging countries. Full article
(This article belongs to the Special Issue Numerical Modeling of Surface Processes)
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Article
Clustering of Long-Period Earthquakes Beneath Gorely Volcano (Kamchatka) during a Degassing Episode in 2013
Geosciences 2020, 10(6), 230; https://doi.org/10.3390/geosciences10060230 - 14 Jun 2020
Cited by 4 | Viewed by 1193
Abstract
Gorely is one of the most active volcanoes in Kamchatka with a rich magmatic and eruptive history reflected in its composite structure. In 2013–2014, a temporary network of 20 seismic stations was installed on Gorely for one year. During the four months of [...] Read more.
Gorely is one of the most active volcanoes in Kamchatka with a rich magmatic and eruptive history reflected in its composite structure. In 2013–2014, a temporary network of 20 seismic stations was installed on Gorely for one year. During the four months of its high degassing rate, seismic activity was mostly expressed in the form of a long-period (LP) seismic tremor. In this study, we have developed a workflow based on the combination of back-projection (BP), cluster analysis, and matched-filter (MF) methods. By applying it to continuous seismic records for the study period, we were able to identify discrete LP events within the tremor sequence automatically and individually investigate their properties. A catalog obtained using the BP detection algorithm consist of 1741 high-energy events. Cluster analysis revealed that the entire variety of LP earthquakes in this catalog could be grouped into five families, which are sequentially organized in time. Utilizing templates of these families in the MF search resulted in the complementary catalog of 80,615 low-energy events. The long-term occurrence of highly repetitive LP events in the same location may correspond to resonating conduits behaving in response to the high-pressure gases flowing from the decompressed magma chamber up to the volcano’s crater. Full article
(This article belongs to the Special Issue Magma Reservoir Dynamics)
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Article
The Role of the Water Level in the Assessment of Seismic Vulnerability for the 23 November 1980 Irpinia–Basilicata Earthquake
Geosciences 2020, 10(6), 229; https://doi.org/10.3390/geosciences10060229 - 13 Jun 2020
Cited by 6 | Viewed by 1130
Abstract
The seismic vulnerability of structures is closely related to changes in the degree of soil saturation that may cause significant changes in volume and shear strength, and consequently, bearing capacity. This paper aims to consider this issue during the strong earthquake that struck [...] Read more.
The seismic vulnerability of structures is closely related to changes in the degree of soil saturation that may cause significant changes in volume and shear strength, and consequently, bearing capacity. This paper aims to consider this issue during the strong earthquake that struck Southern Italy on 23 November 1980 (Ms = 6.9) and affected the Campania and Basilicata regions. Several 3D numerical finite element models were performed in order to consider the effects of soil–structure interaction (SSI) on a representative benchmark structure. In particular, the role of the water level depth is herein considered as one of the most significant parameters to control the shear deformations inside the soil, and thus the performance of the superstructure. Results show the importance of considering the water level for buildings on shallow foundations in terms of settlements, base shear forces and floor displacements. Full article
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Article
The Role of Cover Thickness in the Rainfall-Induced Landslides of Nocera Inferiore 2005
Geosciences 2020, 10(6), 228; https://doi.org/10.3390/geosciences10060228 - 11 Jun 2020
Cited by 2 | Viewed by 1090
Abstract
In the context of rainfall-induced landslides involving pyroclastic soils, the present work analyzes the influence of cover thickness on slope stability conditions. To this aim, the slope failure that occurred in Nocera Inferiore (4th March 2005) is selected as a reference test case, [...] Read more.
In the context of rainfall-induced landslides involving pyroclastic soils, the present work analyzes the influence of cover thickness on slope stability conditions. To this aim, the slope failure that occurred in Nocera Inferiore (4th March 2005) is selected as a reference test case, providing the actual weather forcing history that preceded the event, the hydraulic characterization of the soil involved, and the lowermost boundary condition (variously fractured calcareous bedrock underlying the cover). By maintaining unchanged soil hydraulic properties, the relationship between domain thickness, initial soil suction distribution, and slope instability induced by critical rainfall is investigated by numerical analyses. These refer to a rigid unsaturated domain subject to one dimensional flow conditions under the effects of incoming (precipitation) and outcoming (evaporation) fluxes applied at the uppermost boundary. The main outcomes indicate that critical event duration increases significantly with increasing the domain thickness. This relationship is strongly influenced by initial suction distribution. A linear relationship results for soil suction that is assumed to be constant at the beginning of the critical event. However, this relationship is quadratic if, by simulating the actual antecedent meteorological conditions, suction at the beginning of the critical event is the main function of the domain thickness. Additional numerical analyses were carried out to characterize the influence of a different lowermost boundary condition. Outcomes indicate that, for the same thickness, critical duration is substantially longer if the cover contact is with the same material as that of the cover. Full article
(This article belongs to the Special Issue Innovative Strategies for Sustainable Mitigation of Landslide Risk)
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Article
Non-Associated Flow Rule-Based Elasto-Viscoplastic Model for Clay
Geosciences 2020, 10(6), 227; https://doi.org/10.3390/geosciences10060227 - 10 Jun 2020
Cited by 3 | Viewed by 1357
Abstract
We develop a non-associated flow rule (NAFR)-based elasto-viscoplastic (EVP) model for isotropic clays. For the model formulation, we introduce the critical state soil mechanics theory (CSSMT), the bounding surface theory and Perzyna’s overstress theory. The NAFR based EVP model comprises three surfaces: the [...] Read more.
We develop a non-associated flow rule (NAFR)-based elasto-viscoplastic (EVP) model for isotropic clays. For the model formulation, we introduce the critical state soil mechanics theory (CSSMT), the bounding surface theory and Perzyna’s overstress theory. The NAFR based EVP model comprises three surfaces: the potential surface, the reference surface and the loading surface. Additionally, in the model formulation, assuming the potential surface and the reference surface are identical, we obtain the associated flow rule-based EVP model. Both EVP models require seven parameters and five of them are identical to the Modified Cam Clay model. The other two parameters are the surface shape parameter and the secondary compression index. Moreover, we introduce the shape parameter in the model formulation to control the surface shape and to account for the overconsolidation state of clay. Additionally, we incorporate the secondary compression index to introduce the viscosity of clay. Also, we validate the EVP model performances for the Shanghai clay, the San Francisco Bay Mud (SFBM) clay and the Kaolin clay. Furthermore, we use the EVP models to predict the long-term field monitoring measurement of the Nerang Broadbeach roadway embankment in Australia. From the comparison of model predictions, we find that the non-associated flow rule EVP model captures well a wide range of experimental results and field monitoring embankment data. Furthermore, we also observe that the natural clay exhibits the flow rule effect more compared to the reconstituted clay. Full article
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Article
Modelling with Volna-OP2—Towards Tsunami Threat Reduction for the Irish Coastline
Geosciences 2020, 10(6), 226; https://doi.org/10.3390/geosciences10060226 - 10 Jun 2020
Cited by 2 | Viewed by 1891
Abstract
Tsunamis are infrequent events that have the potential to be extremely destructive. The last major tsunami to effect the Irish coastline was the Lisbon 1755 event. That event acts as a candidate worst case scenario for hazard assessment and the impacts on the [...] Read more.
Tsunamis are infrequent events that have the potential to be extremely destructive. The last major tsunami to effect the Irish coastline was the Lisbon 1755 event. That event acts as a candidate worst case scenario for hazard assessment and the impacts on the Irish Coastline are presented here. As there is no general consensus on the 1755 earthquake source, multiple sources highlighted in the literature are investigated. These sources are used to generate the initial conditions and the resultant tsunami waves are simulated with the massively parallelised Volna-OP2 finite volume tsunami code. The hazard associated with the event is captured on three gradated levels. A reduced faster than real time tsunami ensemble is produced for the North-East Atlantic on a regional level in 93 s using two Nvidia V100 GPUs. By identifying the most vulnerable sections of the Irish coastline from this regional forecast, some locally refined simulations are further carried out in a faster than real time setting. As arrival times on the coastline can be on the O (mins), these faster than real time reduced ensembles are of great benefit for tsunami warning. Volna-OP2’s capabilities in this respect are clearly demonstrated here. Finally, high resolution inundation simulations, which build upon the ensemble results, are carried out. To date this study provides the best estimate of assessing the hazard associated with a Lisbon-type tsunami event for the Irish coastline. The results of the inundation mapping highlight that along the vulnerable sections of coastline, inundation is constrained to low-lying areas with maximum run-up heights of 3.4 m being found. Full article
(This article belongs to the Special Issue Advances in tsunami science towards tsunami threat reduction)
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Article
Imaging Buried Archaeological Features through Ground Penetrating Radar: The Case of the Ancient Saepinum (Campobasso, Italy)
Geosciences 2020, 10(6), 225; https://doi.org/10.3390/geosciences10060225 - 09 Jun 2020
Cited by 8 | Viewed by 1133
Abstract
The archaeological area of Saepinum is considered the symbol of the history of Roman civilization in Molise region (Italy). It was a Samnite commercial forum and service center, then it became a Roman municipium, and, later, it was transformed into a medieval and [...] Read more.
The archaeological area of Saepinum is considered the symbol of the history of Roman civilization in Molise region (Italy). It was a Samnite commercial forum and service center, then it became a Roman municipium, and, later, it was transformed into a medieval and modern rural village. Although the archaeological excavations brought to light different important public buildings, such as the theater, the forum, the basilica, different temples, and the main streets, today, there is still much to discover and study inside the well-preserved city walls. For this purpose, a ground penetrating radar (GPR) survey was realized in the space between the theater and the decumanus, allowing imaging of a complex regular pattern of archaeological features belonging to thermal buildings still buried in the soil. Full article
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Article
Determiners in the Consumer’s Purchase Decision Process in Ecotourism Contexts: A Portuguese Case Study
Geosciences 2020, 10(6), 224; https://doi.org/10.3390/geosciences10060224 - 09 Jun 2020
Cited by 11 | Viewed by 1583
Abstract
Purpose: This paper entails a reflection on sustainability and specific tourism contexts (i.e., ecotourism). It focusses mainly on local communities’ determiners in the consumer’s purchase decision process in ecotourism. This research aimed at understanding the determiners in the process of consumer decisions in [...] Read more.
Purpose: This paper entails a reflection on sustainability and specific tourism contexts (i.e., ecotourism). It focusses mainly on local communities’ determiners in the consumer’s purchase decision process in ecotourism. This research aimed at understanding the determiners in the process of consumer decisions in ecotourism contexts, as well as verifying the growing importance of ecotourism. Methodology: A questionnaire was conducted (with ecotourism specific contexts), in Portugal. Portugal is a tourist destination that has gained notoriety and recognition in recent years. In total, 197 questionnaires were collected, aiming for a deeper understanding of the real social, economic, cultural and environmental impacts resulting from the uncontrolled development of tourism. This study aimed at testing the proposed conceptual model empirically (i.e., the relationship between destination image and post-purchase behaviour). Findings: Sustainability must be looked at as a vital need for society in general, as well as for the tourism sector. Ecotourism is the natural evolution of tourism employing care for the environment, culture and local traditions, while promoting environmental education. Research Limitations: The results obtained are limited, considering the availability of most accommodation units in the ecotourism segment in Portugal (e.g., hotels). As next steps, it is advisable that hotel units come to realise the pertinence of such research as they are the main beneficiaries of these initiatives, being then recommended that they collaborate with the process of completing surveys. Originality/Value: Managers and ecotourists can use the outcomes of this study to gain an in-depth understanding of customer experiences (i.e., sustainability experiences), to develop effective marketing strategies, and to create an operational environment that can maximise customers’ perceived experiential values. Destination image plays a fundamental part in terms of experience and the tourist’s own satisfaction, with a need to improve the degree of affectivity towards the hotel unit. Full article
(This article belongs to the Special Issue Sustainable Tourism,Geography and Spatial Planning)
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Article
In Situ Block Size Distribution Aimed at the Choice of the Design Block for Rockfall Barriers Design: A Case Study along Gardesana Road
Geosciences 2020, 10(6), 223; https://doi.org/10.3390/geosciences10060223 - 07 Jun 2020
Cited by 9 | Viewed by 1160
Abstract
When studying rockfall phenomena, a single value of the block volume is not sufficient to take into account the natural variability of the geometrical features (orientation, spacing, persistence) of the discontinuity sets. Different approaches for obtaining cumulative distributions of potentially detachable block volumes [...] Read more.
When studying rockfall phenomena, a single value of the block volume is not sufficient to take into account the natural variability of the geometrical features (orientation, spacing, persistence) of the discontinuity sets. Different approaches for obtaining cumulative distributions of potentially detachable block volumes are compared. A highly fractured rock mass outcropping along the western Lake Garda (Italy), consisting of prevailing limestone and interbedded marls, is studied in detail from geological and geostructural points of view. Then, a representative rock face has been selected and analyzed with traditional and non-contact survey methods to identify the main discontinuity sets and to collect spacing samples. Based on these data, in situ block size distributions for different combinations of sets are built following statistically-based approaches, without the use of a Discrete Fracture Network (DFN) generator. The validation of the obtained distributions is attempted based on the detached block surveyed at the foot of the slope. However, in this particular case study, the detached blocks cover only a minimal volume range compared to both theoretical values and visible rockfall scars. The fallen rock blocks have a marginal role in design block determination, since their volume depends on geological discontinuities (bedding and fractures) and could be affected by other processes after the detachment (e.g., fragmentation). The procedure here described should be standard practice in the study of rockfall events, and it should be uniform in European standards such as Eurocodes. Future developments should involve the scientific community for setting the percentiles of the probability distribution to be considered for block design definition. Full article
(This article belongs to the Special Issue Rockfall Hazard)
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Article
Assessment of Geotechnical Seismic Isolation (GSI) as a Mitigation Technique for Seismic Hazard Events
Geosciences 2020, 10(6), 222; https://doi.org/10.3390/geosciences10060222 - 06 Jun 2020
Cited by 6 | Viewed by 1448
Abstract
Geotechnical seismic isolation (GSI) has emerged as a potential technique to mitigate the effects of earthquakes, with many applications to structural configurations, such as bridges and buildings. It consists of absorbing the seismic energy from the soil to the superstructure by interposing a [...] Read more.
Geotechnical seismic isolation (GSI) has emerged as a potential technique to mitigate the effects of earthquakes, with many applications to structural configurations, such as bridges and buildings. It consists of absorbing the seismic energy from the soil to the superstructure by interposing a superficial soil layer in order to reduce the accelerations that filter from the soil to the structure. This mitigation technique is particularly suitable in developing countries since GSIs are low-cost seismic isolation systems that through relatively simple manufacturing processes allow to safe costs and stimulate many applications. The presented study aimed to perform 3D numerical finite element models that overcome the previous contributions by performing several structural configurations. Several historical earthquakes are considered in this paper, and the results may be applied to drive general assessments of the technique in case of future seismic hazards. Full article
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Article
Inverse Simulation for Extracting the Flow Characteristics of Artificial Snow Avalanches Based on Computation Fluid Dynamics
Geosciences 2020, 10(6), 221; https://doi.org/10.3390/geosciences10060221 - 06 Jun 2020
Cited by 2 | Viewed by 967
Abstract
Many numerical analysis methods for predicting the motion of soil or snow avalanches may set the characteristics of the dynamic friction obtained from field tests, such as the measurement of real avalanche and model slope tests. However, the friction characteristics of the actual [...] Read more.
Many numerical analysis methods for predicting the motion of soil or snow avalanches may set the characteristics of the dynamic friction obtained from field tests, such as the measurement of real avalanche and model slope tests. However, the friction characteristics of the actual flow of objects are influenced by changes in the velocity and density of the flowing objects and are not necessarily constant. In addition, determining the shear strain rate dependence of the frictional properties at low shear strain rates is important for accurately predicting the avalanche reach distance. In this research, model tests using a rotating drum device were carried out, and an artificial snow avalanche was generated. Then, the flow velocity distribution of the flow was extracted by organizing the motion of the artificial snow avalanche flowing in the drum device using the Digital Image Correlation method. Moreover, the changing characteristics of the viscosity coefficient of the pseudo flow were estimated using an inverse simulation. For the results, it was suggested that the method of estimating flow characteristics and friction characteristics from the artificial avalanche generated by the rotating drum and the time inverse analysis proposed in this study was effective, but it is necessary to confirm the issue of the need for a similar analysis using real scale. If it is found to be applicable to real scales in the future, it will contribute to the development of this field because it will expand the range of methods for analyzing avalanches using model experiments. Full article
(This article belongs to the Special Issue Snow Avalanche Dynamics)
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Article
Rockfall Hazard Assessment in Volcanic Regions Based on ISVS and IRVS Geomechanical Indices
Geosciences 2020, 10(6), 220; https://doi.org/10.3390/geosciences10060220 - 06 Jun 2020
Cited by 3 | Viewed by 1786
Abstract
In volcanic regions, rockfalls represent a major hazard strongly conditioned by the geomechanical behaviour of volcanic materials, the geomorphological characteristics of the relief and the climatic conditions. Volcanic rocks possess very different properties to those of other lithological groups, presenting highly heterogeneous geomechanical [...] Read more.
In volcanic regions, rockfalls represent a major hazard strongly conditioned by the geomechanical behaviour of volcanic materials, the geomorphological characteristics of the relief and the climatic conditions. Volcanic rocks possess very different properties to those of other lithological groups, presenting highly heterogeneous geomechanical behaviours. Nevertheless, they have received little research attention in the field of geological and geotechnical engineering. To date, the application of geomechanical classifications to characterise and estimate volcanic slope stability has not yielded reliable results, indicating the need to establish specific criteria for these rocks. Consequently, we developed indices to estimate rockfall susceptibility, hazard and risk in volcanic slopes. The index of susceptibility for volcanic slopes (ISVS) is designed to estimate slope susceptibility to instability, which is related to the level of hazard, while the index of risk for volcanic slopes (IRVS) is designed to estimate the level of risk as a function of the potential damage or economic loss caused as a result of rockfalls on slopes. Both indices were developed in order to provide an easily applied procedure that facilitates the adoption of short-term preventive measures against rockfalls. The indices were applied in Tenerife (Canary Islands), which presents exceptional conditions for analysing slope stability in volcanic rocks because of its mountainous orography with very steep slopes and a wide variety of materials. These conditions have frequently precipitated slope instability, causing significant damage to housing, beaches, roads and other infrastructures. After applying these indices to a number of slopes representative of the island’s wide variety of geological, geomorphological and climatic conditions, the results obtained were compared with the actual behaviour of the slopes, determined from extensive rockfall inventory data and in situ geomechanical surveys. Full article
(This article belongs to the Special Issue Rockfall Hazard)
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Article
Down-Sampling of Large LiDAR Dataset in the Context of Off-Road Objects Extraction
Geosciences 2020, 10(6), 219; https://doi.org/10.3390/geosciences10060219 - 04 Jun 2020
Cited by 2 | Viewed by 920
Abstract
Nowadays, LiDAR (Light Detection and Ranging) is used in many fields, such as transportation. Thanks to the recent technological improvements, the current generation of LiDAR mapping instruments available on the market allows to acquire up to millions of three-dimensional (3D) points per second. [...] Read more.
Nowadays, LiDAR (Light Detection and Ranging) is used in many fields, such as transportation. Thanks to the recent technological improvements, the current generation of LiDAR mapping instruments available on the market allows to acquire up to millions of three-dimensional (3D) points per second. On the one hand, such improvements allowed the development of LiDAR-based systems with increased productivity, enabling the quick acquisition of detailed 3D descriptions of the objects of interest. However, on the other hand, the extraction of the information of interest from such huge amount of acquired data can be quite challenging and time demanding. Motivated by such observation, this paper proposes the use of the Optimum Dataset method in order to ease and speed up the information extraction phase by significantly reducing the size of the acquired dataset while preserving (retain) the information of interest. This paper focuses on the data reduction of LiDAR datasets acquired on roads, with the goal of extraction the off-road objects. Mostly motivated by the need of mapping roads and quickly determining car position along a road, the development of efficient methods for the extraction of such kind of information is becoming a hot topic in the research community. Full article
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Article
Sea Level Trend and Fronts in the South Atlantic Ocean
Geosciences 2020, 10(6), 218; https://doi.org/10.3390/geosciences10060218 - 03 Jun 2020
Cited by 6 | Viewed by 1857
Abstract
The understanding of the physical drivers of sea level trend is crucial on global and regional scales. In particular, little is known about the sea level trend in the South Atlantic Ocean in comparison with other parts of the world. In this work, [...] Read more.
The understanding of the physical drivers of sea level trend is crucial on global and regional scales. In particular, little is known about the sea level trend in the South Atlantic Ocean in comparison with other parts of the world. In this work, we computed the South Atlantic mean sea level (SAMSL) trend from 25 years of satellite altimetry data, and we analyzed the contributions of steric height (thermosteric and halosteric components) and ocean mass changes for the period 2005–2016 when all the source data used (Argo, GRACE and satellite altimetry) overlap. The SAMSL trend is 2.65 ± 0.24 mm/yr and is mostly explained by ocean mass trend, which is 2.22 ± 0.21 mm/yr. However, between 50° S–33° S, the steric height component constitutes the main contribution in comparison with the ocean mass component. Within that latitudinal band, three regions with trend values higher than the SAMSL trend are observed when considering 25 years of satellite SLA. In the three regions, a southward displacement of the Subtropical, Subantarctic, and Polar Fronts is observed. The southward shift of the fronts is associated with the strengthening and polar shift of westerly winds and contributes to a clear thermosteric trend that translates to the SLA trend observed in those regions. Full article
(This article belongs to the Special Issue Satellite Observations of Sea Level and Ocean Circulation)
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