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Geosciences, Volume 8, Issue 3 (March 2018)

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Cover Story (view full-size image) The worlds’ best-known fossil forests contain wood that has been mineralized with silica. Less [...] Read more.
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Open AccessArticle Geomorphology and Late Pleistocene–Holocene Sedimentary Processes of the Eastern Gulf of Finland
Geosciences 2018, 8(3), 102; https://doi.org/10.3390/geosciences8030102
Received: 8 December 2017 / Revised: 8 March 2018 / Accepted: 14 March 2018 / Published: 18 March 2018
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Abstract
In 2017, a detailed study of the Eastern Gulf of Finland (the Baltic Sea) seafloor was performed to identify and map submerged glacial and postglacial geomorphologic features and collect data pertinent to the understanding of sedimentation in postglacial basins. Two key areas within
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In 2017, a detailed study of the Eastern Gulf of Finland (the Baltic Sea) seafloor was performed to identify and map submerged glacial and postglacial geomorphologic features and collect data pertinent to the understanding of sedimentation in postglacial basins. Two key areas within the Gulf were investigate using a multibeam echosounder, SeaBat 8111 and an EdgeTech 3300-HM acoustic sub-bottom profiling system. High-resolution multibeam bathymetric data (3-m resolution) were used to calculate aspect, slope, terrain ruggedness and bathymetric position index using ArcGIS Spatial Analyst and the Benthic Terrain Modeler toolbox. These data and resultant thematic maps revealed, for the first time, such features as streamlined till ridges, end-moraine ridges, and De Geer moraines that are being used for the reconstruction of the deglaciation in the Eastern Gulf of Finland. This deglaciation occurred between 13.8 and 13.3 ka BP (Pandivere–Neva stage) and 12.25 ka BP (Salpausselkä I stage). Interpretations of the seismic-reflection profiles and 3D models showing the surfaces of till, and the identification of the Late Pleistocene sediment and modern bottom relief, indicate deep relative water-level fall in the Early Holocene and, most likely, several water-level fluctuations during this time. Full article
(This article belongs to the Special Issue Marine Geomorphometry)
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Open AccessArticle SPI Trend Analysis of New Zealand Applying the ITA Technique
Geosciences 2018, 8(3), 101; https://doi.org/10.3390/geosciences8030101
Received: 28 February 2018 / Revised: 8 March 2018 / Accepted: 13 March 2018 / Published: 15 March 2018
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Abstract
A natural temporary imbalance of water availability, consisting of persistent lower-than-average or higher-than-average precipitation, can cause extreme dry and wet conditions that adversely impact agricultural yields, water resources, infrastructure, and human systems. In this study, dry and wet periods in New Zealand were
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A natural temporary imbalance of water availability, consisting of persistent lower-than-average or higher-than-average precipitation, can cause extreme dry and wet conditions that adversely impact agricultural yields, water resources, infrastructure, and human systems. In this study, dry and wet periods in New Zealand were expressed using the Standardized Precipitation Index (SPI). First, both the short term (3 and 6 months) and the long term (12 and 24 months) SPI were estimated, and then, possible trends in the SPI values were detected by means of a new graphical technique, the Innovative Trend Analysis (ITA), which allows the trend identification of the low, medium, and high values of a series. Results show that, in every area currently subject to drought, an increase in this phenomenon can be expected. Specifically, the results of this paper highlight that agricultural regions on the eastern side of the South Island, as well as the north-eastern regions of the North Island, are the most consistently vulnerable areas. In fact, in these regions, the trend analysis mainly showed a general reduction in all the values of the SPI: that is, a tendency toward heavier droughts and weaker wet periods. Full article
(This article belongs to the Special Issue Hydrological Hazard: Analysis and Prevention) Printed Edition available
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Open AccessArticle Regional Geomorphological Conditions Related to Recent Changes of Glacial Lakes in the Issyk-Kul Basin, Northern Tien Shan
Geosciences 2018, 8(3), 99; https://doi.org/10.3390/geosciences8030099
Received: 24 October 2017 / Revised: 2 February 2018 / Accepted: 7 February 2018 / Published: 14 March 2018
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Abstract
To assess the current state of glacial lakes, we examine the seasonal lake-area changes of 339 glacial lakes in the Teskey and Kungoy Ranges of the Issyk-Kul Basin, Kyrgyzstan, during 2013–2016 based on optical satellite images (Landsat7/ETM+ and 8/OLI). The glacial lakes are
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To assess the current state of glacial lakes, we examine the seasonal lake-area changes of 339 glacial lakes in the Teskey and Kungoy Ranges of the Issyk-Kul Basin, Kyrgyzstan, during 2013–2016 based on optical satellite images (Landsat7/ETM+ and 8/OLI). The glacial lakes are classified into six types based on their seasonal variations in area: stable, increasing, decreasing, appearing, vanishing, and short-lived. We then track the number of each type in a given year and examine how each number changes from one year to the next. We find that many appearing, vanishing, and short-lived types occurred in both mountain ranges, having a large variability in number that is not directly related to the local short-term summer temperature anomaly, nor to precipitation or glacier recession. However, those in the Teskey Range vary significantly more than those in the Kungoy Range. To determine if the changing number and distribution of the various lake types may be due to changes in ground ice, we apply differential interferometric synthetic aperture radar (DInSAR) analysis using ALOS-2/PALSAR-2 for the debris landforms behind which glacial lakes appear. In the Teskey Range, ground ice occurs in 413 out of a total of 930 debris landforms, whereas in the Kungoy Range, ground ice occurs in 71 out of 180. In zones with predominant glacier-retreat during 1971–2010 (from Corona KH-4B and ALOS/PRISM), the Teskey Range had 180 new lake depressions as potential lake-basins, whereas the Kungoy Range had just 22. Existing depressions also expanded when melting ice produced subsidence. Such subsidence, together with debris landforms containing ground ice and ice tunnels, appear to cause the observed large number variability. In particular, the deposition of ice and debris by tunnel collapse or the freezing of storage water in a debris landform may close-off an ice tunnel, causing a lake to appear. Subsequent re-opening via melting of such blockage would produce either a vanishing or a short-lived type. In this way, the large variability in the number of each lake type and the distribution of types over this four-year period arises from regional geomorphological conditions and not directly from the local short-term summer temperature anomaly and precipitation or glacier recession. Full article
(This article belongs to the Special Issue Cryosphere)
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Open AccessCommunication An Emerging Paradigm for the UNESCO Global Geoparks: The Ecosystem’s Health Provision
Geosciences 2018, 8(3), 100; https://doi.org/10.3390/geosciences8030100
Received: 12 February 2018 / Revised: 8 March 2018 / Accepted: 9 March 2018 / Published: 14 March 2018
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Abstract
During the 38th General Conference of UNESCO, the Member States ratified the creation of the International Geoscience and Geoparks Programme (IGGP) expressing governmental recognition of the importance of managing outstanding geological sites and landscapes in a holistic manner. In this context, the importance
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During the 38th General Conference of UNESCO, the Member States ratified the creation of the International Geoscience and Geoparks Programme (IGGP) expressing governmental recognition of the importance of managing outstanding geological sites and landscapes in a holistic manner. In this context, the importance of human interactions with the natural environment to promote healthy lifestyles was primarily a response to the need to preserve and enhance the value of the UNESCO Global Geoparks as well as highlighting their usefulness for the sustainable development of local populations. The aim of this paper is to suggest an interdisciplinary approach to be applied to UNESCO Global Geoparks for a standardized survey and grading methodology that can be used to assess the ability to provide and promote healthy lifestyles, which is called the Ecosystem’s Health Provision Spectrum (EHPS) on an ecological scale. The suggested EHPS is in line with UNESCO’s priorities, in particular with the IGGP and its motto of “Geosciences in the Service of Society”. Therefore, the EHPS on an ecological scale will be another important tool for the UNESCO Global Geoparks, facilitating efficient management and promoting economic development, wellbeing and health. Full article
(This article belongs to the Special Issue Selected Papers from the “14th European Geoparks Conference”)
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Open AccessArticle Environmental and Health: The Importance of Tremolite Occurence in the Pollino Geopark (Southern Italy)
Geosciences 2018, 8(3), 98; https://doi.org/10.3390/geosciences8030098
Received: 24 January 2018 / Revised: 8 March 2018 / Accepted: 8 March 2018 / Published: 13 March 2018
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Abstract
Worldwide studies have been done about the toxicity and carcinogenicity of asbestos minerals occurring in ophiolitic rocks. Inhalation of asbestos due to environmental exposure could cause malignant mesothelioma and lung cancers. In particular, the ophiolitic rocks in Tethyan realm represents a serious enivironmental
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Worldwide studies have been done about the toxicity and carcinogenicity of asbestos minerals occurring in ophiolitic rocks. Inhalation of asbestos due to environmental exposure could cause malignant mesothelioma and lung cancers. In particular, the ophiolitic rocks in Tethyan realm represents a serious enivironmental concern due to both the presence of asbestos-like minerals and the large Cr abundance that is prone to solubilisation as CrVI. At the Pollino Geopark (southern Apennines, Italy), serpentinites-rich ophiolite rocks and sediments of the Frido Unit crop-out. In these rocks, tremolite, an asbestos-like mineral, is typically intergrown with fibrous antigorite and chrysotile. Tremolite shows acicular, friable, fibrous, and elongated habitus, can be easily released into the environment as a result of both natural processes and anthropogenic activities. In the analyzed rocks, tremolite is present mainly in veins as much as in the matrix and forms crowns around clinopyroxene porphyroclasts. The different analytical techniques showed the recognition of the amphibole-like minerals (actinolite and tremolite) that are the dominant phases, with a small percentage of Fe2+. The presence of Fe in the “ideal” tremolite asbestos could cause pathological effects for the human living in the Pollino Geopark. This study has several environmental relevant implications, including, for example, the realization of national health protecting programs and the mapping of natural sites characterized by the presence of asbestos minerals in Pollino Geopark and in others area where outcrop asbestos bearing ophiolitic rocks. Full article
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Open AccessArticle Lanthanides and Actinides in Humic Acids of Soils and Paleosols of Forest-Steppe Conditions in the Southern Urals
Geosciences 2018, 8(3), 97; https://doi.org/10.3390/geosciences8030097
Received: 19 January 2018 / Revised: 25 February 2018 / Accepted: 6 March 2018 / Published: 13 March 2018
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Abstract
This article analyzes the lanthanum, cerium, samarium, europium, terbium, ytterbium, lutetium, uranium, and thorium content in humic acids within soil and paleosol surface horizons from the southern steppe in the Southern Urals. Research demonstrates similar accumulation levels of these elements in paleosols isolated
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This article analyzes the lanthanum, cerium, samarium, europium, terbium, ytterbium, lutetium, uranium, and thorium content in humic acids within soil and paleosol surface horizons from the southern steppe in the Southern Urals. Research demonstrates similar accumulation levels of these elements in paleosols isolated from both the active medium between 3.6 and 3.3 thousand years ago and in recent background soils. Despite the lack of significant differences, research has shown a growing content among the rarest metals in the series “the buried paleosols–man-modified paleosols of settlement–recent background soils”. Research has detected the lowest content of La, Ce, Sm, Eu, Yb, Lu, and Th in preparations of humic acids of recent background soils. This reveals a close content to most elements in humic acids of paleosols buried under barrows and ancient settlement paleosols. Additionally, it indicates the virtual absence of anthropogenic impact on binding lanthanides and actinides by humic acids in ancient times. The contribution of humic acids into the common pool for each element was evaluated using a special approach. Research showed that there was less than half the share of elements associated by humic acids of paleosols than in the recent background chernozems in the total pool of lanthanides and actinides. This article considers the prospects of using humic acids of recent and ancient soils in identifying behavioral patterns of metal complexes through time. Full article
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Open AccessArticle Combined Use of Remote Sensing Data, Mineralogical Analyses, Microstructure Studies and Geographic Information System for Geological Mapping of Antiparos Island (Greece)
Geosciences 2018, 8(3), 96; https://doi.org/10.3390/geosciences8030096
Received: 22 December 2017 / Revised: 2 March 2018 / Accepted: 5 March 2018 / Published: 12 March 2018
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Abstract
This study presents the combined use of field mapping, remote sensing data analysis, mineralogy, spectroscopy and GIS techniques for the geological mapping of Antiparos Island. Antiparos is part of the Cyclades Blueschist Belt located in central Aegean, where gneisses, schists and Pliocene volcanic
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This study presents the combined use of field mapping, remote sensing data analysis, mineralogy, spectroscopy and GIS techniques for the geological mapping of Antiparos Island. Antiparos is part of the Cyclades Blueschist Belt located in central Aegean, where gneisses, schists and Pliocene volcanic rocks occurred. During the extended field work, a number of volcanic rock samples were collected from the southern part of Antiparos. The sampling strategy was to collect samples from the primary as well as the altered rocks in specific areas in which they were previously located from the remote sensing data processing. In this study, high resolution satellite images have been carried out in order to detect, allocate and separate the different geological formations. Furthermore, the existing geological map was georeferenced and all the tectonic lines and boundaries were digitized. All these features were implemented in a Mobile Mapper CE GPS using Arcpad GIS and checked in situ. The collected samples were analyzed in the laboratory using various techniques including XRD, Petrographic Microscopy and SEM. The qualitative mineralogical analyses were conducted by using XRD. The study was supplemented by the petrographic observations providing a detailed characterization of rock textures. In addition, SEM study and SEM-EDS analyses of the samples were emphasized on the genetic relations of the minerals. The laboratory results revealed that specific corrections should be made in the previous geological map of Antiparos concerning the volcanic rocks, especially at the southern part of the island. A significant conclusion is that the rock described as volcanic in the previous map proved to be a fossiliferous limestone which includes micritic matrix of calcite with an insignificant amount of fossils. All the analogical and digital data and the results of the petrographic analysis were imported in a geodatabase specially designed for geological data. After the necessary topological control and corrections, the data were unified and processed in order to create the final layout at 1/25.000 scale. Full article
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Open AccessArticle Release, Migration, Sorption, and (Re)Precipitation of U during Peraluminous Granite Alteration under Oxidizing Conditions in Central Portugal
Geosciences 2018, 8(3), 95; https://doi.org/10.3390/geosciences8030095
Received: 25 November 2017 / Revised: 8 March 2018 / Accepted: 9 March 2018 / Published: 12 March 2018
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Abstract
In this work, in order to study the release, migration, sorption, and (re)precipitation of uranium (U) during alteration under oxidizing conditions, we carried out a systematic study using scanning electron microscopy, X-ray maps, and electron microprobe analyses on uranium minerals—such as uraninite, coffinite,
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In this work, in order to study the release, migration, sorption, and (re)precipitation of uranium (U) during alteration under oxidizing conditions, we carried out a systematic study using scanning electron microscopy, X-ray maps, and electron microprobe analyses on uranium minerals—such as uraninite, coffinite, saleeite, meta-saleeite, and thorite—and U-bearing minerals—such as xenotime, monazite, apatite, and zircon—from unaltered and altered Variscan peraluminous granites and related hydrothermal brecciated uranium–quartz veins. The paragenetic sequence of the granite and the mineralized quartz veins from Vale the Abrutiga is presented. Uraninite is magmatic in origin and occurs mainly in unaltered granite; it is rare in altered granite, and was not found in the mineralized quartz veins. Uraninite from the altered granite was fractured and hydrated; it had radioactive damage halos filled with late pyrite, U–S-bearing phases, and Fe oxyhydroxides; its analytical totals were also lower than in the uraninite from the unaltered granite. The alteration zones and crystal rims were poorer in U (86.7 wt.% UO2) than in the cores and unaltered zones (90.2 wt.% UO2), and some uraninite crystals were replaced by coffinite, which resulted from uraninite alteration. The U contents in the coffinite crystals ranged between 65.0 wt.% UO2 in the rims to 84.0 wt.% UO2 in the cores of the crystals. Thorite was found in all of the granite samples, and its composition was variable from 0.5 wt.% UO2 to 10.4 wt. % UO2. Some thorite seemed to be primary, whereas the other thorite was related to the granite alteration, replaced apatite and monazite, was associated with xenotime, and filled the fractures of several minerals. In the altered granite, thorite had low UO2 contents (0.46 wt. %) in the fractured crystal zones. Monazite from the altered granite had a pervasive porosity; some crystals were formed by the alteration of apatite, and were frequently replaced by thorite. Monazite and xenotime from the altered granite and hydrothermal veins had lower U contents than these minerals from the unaltered granite. In the altered granite, xenotime crystals were zoned, and their cores were richer in U than the rims. Apatite from the altered granite was fractured, showed dissolution, and had lower U and P contents than the apatite from the unaltered granite. In the quartz veins, apatite crystals were replaced by uranium phosphates and had high U contents (~1.1 wt. % UO2). In the quartz veins, zircon rims had an extraordinary U enrichment (up to 18 wt. % UO2). The most altered rims of chlorite and anatase from the quartz veins were partially replaced by U-bearing Fe oxyhydroxides containing up to 5.7 wt. % UO2. Meteoric water warmed by deep circulation through granite faults, shear zones, and quartz veins became enriched in U, P, and Mg due to the solubilization of mainly uraninite, coffinite, thorite, monazite, apatite, and chlorite. Uranium from these solutions was later adsorbed on Fe oxyhydroxides and the weathered surfaces of anatase, zircon, and apatite, or precipitated as saleeite and meta-saleeite on the surface of Fe minerals and the apatite-weathered surface due to local saturation. Full article
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Open AccessArticle Unified Geomorphological Analysis Workflows with Benthic Terrain Modeler
Geosciences 2018, 8(3), 94; https://doi.org/10.3390/geosciences8030094
Received: 18 January 2018 / Revised: 7 March 2018 / Accepted: 8 March 2018 / Published: 11 March 2018
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Abstract
High resolution remotely sensed bathymetric data is rapidly increasing in volume, but analyzing this data requires a mastery of a complex toolchain of disparate software, including computing derived measurements of the environment. Bathymetric gradients play a fundamental role in energy transport through the
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High resolution remotely sensed bathymetric data is rapidly increasing in volume, but analyzing this data requires a mastery of a complex toolchain of disparate software, including computing derived measurements of the environment. Bathymetric gradients play a fundamental role in energy transport through the seascape. Benthic Terrain Modeler (BTM) uses bathymetric data to enable simple characterization of benthic biotic communities and geologic types, and produces a collection of key geomorphological variables known to affect marine ecosystems and processes. BTM has received continual improvements since its 2008 release; here we describe the tools and morphometrics BTM can produce, the research context which this enables, and we conclude with an example application using data from a protected reef in St. Croix, US Virgin Islands. Full article
(This article belongs to the Special Issue Marine Geomorphometry)
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Open AccessArticle A Basin Approach to a Hydrological Service Delivery System in the Amur River Basin
Geosciences 2018, 8(3), 93; https://doi.org/10.3390/geosciences8030093
Received: 30 November 2017 / Revised: 12 February 2018 / Accepted: 28 February 2018 / Published: 9 March 2018
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Abstract
This paper presents the basin approach to the design, development, and operation of a hydrological forecasting and early warning system in a large transboundary river basin of high flood potential, where accurate, reliable, and timely available daily water-level and reservoir-inflow forecasts are essential
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This paper presents the basin approach to the design, development, and operation of a hydrological forecasting and early warning system in a large transboundary river basin of high flood potential, where accurate, reliable, and timely available daily water-level and reservoir-inflow forecasts are essential for water-related economic and social activities (the Amur River basin case study). Key aspects of basin-scale system planning and implementation are considered, from choosing efficient forecast models and techniques, to developing and operating data-management procedures, to disseminating operational forecasts using web-GIS. The latter, making the relevant forecast data available in real time (via Internet), visual, and well interpretable, serves as a good tool for raising awareness of possible floods in a large region with transport and industrial hubs located alongside the Amur River (Khabarovsk, Komsomolsk-on-Amur). Full article
(This article belongs to the Special Issue Hydrological and Hydrogeological Risks)
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Open AccessArticle Faults as Windows to Monitor Gas Seepage: Application to CO2 Sequestration and CO2-EOR
Geosciences 2018, 8(3), 92; https://doi.org/10.3390/geosciences8030092
Received: 12 January 2018 / Revised: 8 February 2018 / Accepted: 6 March 2018 / Published: 9 March 2018
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Abstract
Monitoring of potential gas seepage for CO2 sequestration and CO2-EOR (Enhanced Oil Recovery) in geologic storage will involve geophysical and geochemical measurements of parameters at depth and at, or near the surface. The appropriate methods for MVA (Monitoring, Verification, Accounting)
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Monitoring of potential gas seepage for CO2 sequestration and CO2-EOR (Enhanced Oil Recovery) in geologic storage will involve geophysical and geochemical measurements of parameters at depth and at, or near the surface. The appropriate methods for MVA (Monitoring, Verification, Accounting) are needed for both cost and technical effectiveness. This work provides an overview of some of the geochemical methods that have been demonstrated to be effective for an existing CO2-EOR (Rangely, CA, USA) and a proposed project at Teapot Dome, WY, USA. Carbon dioxide and CH4 fluxes and shallow soil gas concentrations were measured, followed by nested completions of 10-m deep holes to obtain concentration gradients. The focus at Teapot Dome was the evaluation of faults as pathways for gas seepage in an under-pressured reservoir system. The measurements were supplemented by stable carbon and oxygen isotopic measurements, carbon-14, and limited use of inert gases. The work clearly demonstrates the superiority of CH4 over measurements of CO2 in early detection and quantification of gas seepage. Stable carbon isotopes, carbon-14, and inert gas measurements add to the verification of the deep source. A preliminary accounting at Rangely confirms the importance of CH4 measurements in the MVA application. Full article
(This article belongs to the Special Issue Carbon Sequestration)
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Open AccessArticle Seabed Morphology and Sedimentary Regimes defining Fishing Grounds along the Eastern Brazilian Shelf
Geosciences 2018, 8(3), 91; https://doi.org/10.3390/geosciences8030091
Received: 6 November 2017 / Revised: 26 February 2018 / Accepted: 3 March 2018 / Published: 9 March 2018
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Abstract
Shelf morphology and sedimentary regimes are influenced by processes operating at different temporal and spatial scales and are important records of sea level changes and sediment supply and/or carbonate production. The northern continental shelf of Espírito Santo (Brazil) contains evidence of different sedimentary
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Shelf morphology and sedimentary regimes are influenced by processes operating at different temporal and spatial scales and are important records of sea level changes and sediment supply and/or carbonate production. The northern continental shelf of Espírito Santo (Brazil) contains evidence of different sedimentary regimes that distribute diverse and complex marine habitats. Herein, seabed morphology, acoustic images of the seafloor (side scan sonar and sub-bottom profiler), and sediment samples were used to investigate the influence of sedimentary regimes on physical marine habitat distribution. Seabed mapping is also integrated with available data on fisheries to understand the influence of shelf morphology and sedimentology in the usage of distinct fishing gears. The results indicate five morpho-sedimentary facies: terrigenous mud, terrigenous sand, rhodolith beds, carbonate gravel with rhodoliths, and hardground. Through an integrated analysis of the geomorphology and sedimentary distribution, two morpho-sedimentary domains were identified: a sediment-fed shelf adjacent to the Doce River associated with a major mud depocenter and a delta front morphology characterized by gentle slopes and low terrain ruggedness, and a sediment-starved shelf dominated by carbonate sedimentation showing an irregular morphology associated with higher slopes and terrain ruggedness. These contrasting morpho-sedimentary domains are a result of sedimentary responses to sea level fluctuation during Late Quaternary, specially, during the deglaciation processes after the Last Glacial Maximum. The morphological and sedimentary contrasts along the area define the physical habitat distribution. The sediment supply regime area is associated with a terrigenous fine/muddy sedimentation bed, which control the local morphology and favors coastal and delta front progradation. This physical habitat is a well-known shrimp-fishing ground where intense trawling takes place, as well as gillnet fisheries targeting weakfish and croakers. The accommodation regime or low sediment influx area is characterized by carbonate sedimentation associated with hardgrounds and rhodolith beds. In contrast, this physical habitat with scarce sediment supply, facilitates extensive benthic colonization by crustose coralline algae (CCA), which is primarily associated to line fisheries, longlines, and spearfishing. Rhodoliths show a high diversity of CCA and the occurrence of an endemic kelp species. Long-term processes such as relative sea level fluctuations and sediment supply are a legacy for the distribution of benthic habitats, and their resulting morphology can be a surrogate for predicting fishing activities or a first-base analysis for marine spatial planning. Available low-resolution bathymetric datasets can be a powerful tool, if applied with caution and in a regional scale approach. Here, terrain variables (terrain slope and ruggedness) derived from an extensive available (low-resolution and interpolated) bathymetric dataset distinguished two contrasting morphological domains characterized by rugged and smooth/flat seabeds. Full article
(This article belongs to the Special Issue Marine Geomorphometry)
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Open AccessArticle Springtime Flood Risk Reduction in Rural Arctic: A Comparative Study of Interior Alaska, United States and Central Yakutia, Russia
Geosciences 2018, 8(3), 90; https://doi.org/10.3390/geosciences8030090
Received: 30 November 2017 / Revised: 6 February 2018 / Accepted: 3 March 2018 / Published: 8 March 2018
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Abstract
Every spring, riverine communities throughout the Arctic face flood risk. As the river ice begins to thaw and break up, ice jams—accumulation of chunks and sheets of ice in the river channel, force melt water and ice floes to back up for dozens
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Every spring, riverine communities throughout the Arctic face flood risk. As the river ice begins to thaw and break up, ice jams—accumulation of chunks and sheets of ice in the river channel, force melt water and ice floes to back up for dozens of kilometers and flood vulnerable communities upstream. Via a comparative analysis between two flood-prone communities in Alaska and Yakutia (Siberia), this study examines key components of flood risk—hazards, exposure, and vulnerability, and existing practices in flood risk reduction in rural Arctic. The research sites are two rural communities—Galena (Yukon River) and Edeytsy (Lena River), which sustained major ice-jam floods in May 2013. The data was acquired through a combination of direct observations on site, review of documents and archives, focus group discussions, and surveys. Five focus groups with US and Russian representatives from disaster management agencies revealed a few similar patterns as well as significant differences in flood risk reduction strategies. The main differences included higher reliance on mechanical and short-term ice jam and flood mitigation efforts (e.g., ice-jam demolition) in the Russian Arctic, and lack of a centralized flood management model in the US. Surveys conducted among population at risk during the site visits to Edeytsy (November 2015) and Galena (March 2016) revealed higher satisfaction levels with the existing flood risk reduction efforts among Edeytsy residents. Survey respondents in Galena indicated the lack of ice jam removal and other flood prevention measures as the key drawback in the existing flood management. Historical analysis, conducted via the disaster Pressure and Release (PAR) model, revealed that springtime flood risk in both regions results from complex interactions among a series of natural processes that generate conditions of hazard, and human actions that generate conditions of communities’ exposure and vulnerability. The analysis revealed colonial heritage, top-down governance, and limited inclusion of local communities in the decision-making as the driving forces of vulnerability in both regions. Seasonal weather patterns and regional river channel morphology determine the location, severity, and duration of floods. The analysis also revealed the importance of continuous communication between all stakeholders in timely and effective flood risk management in both regions. Full article
(This article belongs to the Special Issue Hydrological and Hydrogeological Risks)
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Open AccessArticle Squeezed Interstitial Water and Soil Properties in Pleistocene Blue Clays under Different Natural Environments
Geosciences 2018, 8(3), 89; https://doi.org/10.3390/geosciences8030089
Received: 22 December 2017 / Revised: 20 February 2018 / Accepted: 2 March 2018 / Published: 8 March 2018
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Abstract
Studies dating almost a century relate clay properties with the structure of the diffuse double layer (DDL), where the charged surfaces of clay crystal behave like an electric capacitor, whose dielectric is the interstitial fluid. The intensity of the inner electric field relates
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Studies dating almost a century relate clay properties with the structure of the diffuse double layer (DDL), where the charged surfaces of clay crystal behave like an electric capacitor, whose dielectric is the interstitial fluid. The intensity of the inner electric field relates to the concentration and type of ions in the DDL. Other important implications of the model are less stressed: this part of the clay soil system, energetically speaking, is conservative. External contribution of energy, work of overburden or sun driven capillarity and long exposure to border low salinity waters can modify the concentration of pore-waters, thus affecting the DDL geometry, with electric field and energy storage variations. The study of clay soils coming from various natural geomorphological and hydrogeological contexts, determining a different salinity of interacting groundwater, shows how the clay interaction with freely circulating waters at the boundaries produces alterations in the native pore water salinity, and, at the nano-scale, variations of electric field and stored energy from external work. The swelling and the shrinkage of clay soil with their volumetric and geotechnical implications should be regarded as variations of the electrostatic and mechanical energy of the system. The study is based on tests on natural clay soil samples coming from a formation of stiff blue clays, widespread in southern Italy. Geotechnical identification and oedometer tests have been performed, and pore waters squeezed out from the specimens have been analyzed. Tested samples have similar grain size, clay fraction and plasticity; sorted according to the classified geomorphological/hydrogeological contexts, they highlight good correlations among dry density, mechanical work performed in selected stages of the oedometric test, swelling and non-swelling behaviour, and electrical conductivity of the squeezed pore waters. The work performed for swelling and non-swelling samples shows well-defined differences; this endorse the relevance of pore-water salinity in determining the volumetric state of clay soils under overburden and specific hydrogeological border conditions, which together define a specific energetic state. Full article
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Open AccessArticle Repetitive Rockfall Trajectory Testing
Geosciences 2018, 8(3), 88; https://doi.org/10.3390/geosciences8030088
Received: 9 January 2018 / Revised: 8 February 2018 / Accepted: 24 February 2018 / Published: 7 March 2018
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Abstract
Numerical simulations of rockfall trajectories are a standard procedure for evaluating rockfall hazards. For these simulations, corresponding software codes must be calibrated and evaluated based on field data. This study addresses methods of repeatable rockfall tests, and investigates whether it is possible to
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Numerical simulations of rockfall trajectories are a standard procedure for evaluating rockfall hazards. For these simulations, corresponding software codes must be calibrated and evaluated based on field data. This study addresses methods of repeatable rockfall tests, and investigates whether it is possible to produce traceable and statistically analysable data. A testing series is described extensively covering how to conduct rockfall experiments and how certain elements of rockfall trajectories can be measured. The tests use acceleration and rotation sensors inside test blocks, a system to determine block positions over time, surveying measurements, and video recordings. All systems are evaluated regarding their usability in the field and for analyses. The highly detailed description of testing methods is the basis for sound understanding and reproducibility of the tests. This article serves as a reference for future publications and other rockfall field tests, both as a guide and as a basis for comparisons. First analyses deliver information on runout with a shadow angle ranging between 21 and 45 degrees for a slope consisting of homogeneous soft soil. A digital elevation model of the test site as well as point clouds of the used test blocks are part of this publication. Full article
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Open AccessArticle Ambient Vibrations Measurements and 1D Site Response Modelling as a Tool for Soil and Building Properties Investigation
Geosciences 2018, 8(3), 87; https://doi.org/10.3390/geosciences8030087
Received: 21 December 2017 / Revised: 16 February 2018 / Accepted: 2 March 2018 / Published: 6 March 2018
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Abstract
The safety of historic buildings heritage is an important task that becomes more substantial when the buildings are directed to educational purposes. The present study aims at evaluating the dynamic features of the Benedettini complex, an historic monastery located in downtown Catania, which
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The safety of historic buildings heritage is an important task that becomes more substantial when the buildings are directed to educational purposes. The present study aims at evaluating the dynamic features of the Benedettini complex, an historic monastery located in downtown Catania, which is at present the headquarters of the humanistic studies department of the University of Catania. Both the building’s complex response to a seismic input and the soil-to-structure interaction were investigated using ambient noise recordings. The results point out a multiple dynamic behaviour of the monastery structure that shows several oscillation modes, whereas the identification of a single natural frequency can be observed in some sites where the structure can more freely oscillate. This observation is also confirmed by the variability of computed damping values that appear linked to the different rigidity of the structure, as a function of the either the longitudinal or transversal orientation of the investigated structural elements. Moreover, the comparison between the building’s fundamental period and spectral ratios frequencies, which were obtained from free field ambient noise measurements located outside the monastery, outline the presence of potential resonance effects between the site and structure during a seismic event. Numerical modelling of the local seismic response confirms the obtained experimental site frequencies, setting into evidence that higher amplification factors are reached in the same frequency range characterizing the building. Full article
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Open AccessArticle Comparison of Geometric and Volumetric Methods to a 3D Solid Model for Measurement of Gully Erosion and Sediment Yield
Geosciences 2018, 8(3), 86; https://doi.org/10.3390/geosciences8030086
Received: 30 January 2018 / Revised: 23 February 2018 / Accepted: 28 February 2018 / Published: 3 March 2018
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Abstract
Gully erosion is a global problem that degrades land and reduces its utility for agriculture, development, and water quality. Quantification of sediment yield and control of sediment sources is essential for environmental protection. Five methods to evaluate erosion rates and sediment yield on
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Gully erosion is a global problem that degrades land and reduces its utility for agriculture, development, and water quality. Quantification of sediment yield and control of sediment sources is essential for environmental protection. Five methods to evaluate erosion rates and sediment yield on an east Tennessee, USA, hillslope were compared: (1) physical measurement by removal of accumulated sediment using 10 L buckets; (2) repeated measurement of erosion pins in gully (erosional) and delta (depositional) areas; (3) geometric model using a combination trapezoidal prism-cylinder segment; (4) geometric model using a series of trapezoidal pyramids; and (5) 3D solid computer modeling. The 3D solid model created in SolidWorks was selected as the reference model and all other methods overestimated sediment yield to varying degrees. Erosion pin methods overestimated sediment yield by 368% in deltas and 123% in gullies. Volumetric measurement of sediment using buckets overestimated sediment yield by 160% due to void space in the buckets. The trapezoidal prism-cylinder segment model overestimated sediment yield by 66% and the trapezoidal pyramids method overestimated sediment yield by 5.7%. For estimation of sediment trapped behind an elliptical or circular silt fence dam, use of the trapezoidal pyramid method provides a good approximation comparable to 3D solid computer modeling. Full article
(This article belongs to the Special Issue Soil Hydrology and Erosion)
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Open AccessArticle Mineralogy of Non-Silicified Fossil Wood
Geosciences 2018, 8(3), 85; https://doi.org/10.3390/geosciences8030085
Received: 21 December 2017 / Revised: 16 February 2018 / Accepted: 27 February 2018 / Published: 3 March 2018
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Abstract
The best-known and most-studied petrified wood specimens are those that are mineralized with polymorphs of silica: opal-A, opal-C, chalcedony, and quartz. Less familiar are fossil woods preserved with non-silica minerals. This report reviews discoveries of woods mineralized with calcium carbonate, calcium phosphate, various
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The best-known and most-studied petrified wood specimens are those that are mineralized with polymorphs of silica: opal-A, opal-C, chalcedony, and quartz. Less familiar are fossil woods preserved with non-silica minerals. This report reviews discoveries of woods mineralized with calcium carbonate, calcium phosphate, various iron and copper minerals, manganese oxide, fluorite, barite, natrolite, and smectite clay. Regardless of composition, the processes of mineralization involve the same factors: availability of dissolved elements, pH, Eh, and burial temperature. Permeability of the wood and anatomical features also plays important roles in determining mineralization. When precipitation occurs in several episodes, fossil wood may have complex mineralogy. Full article
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Open AccessArticle Stable Hydrogen and Oxygen Isotopes for Groundwater Sources of Penghu Islands, Taiwan
Geosciences 2018, 8(3), 84; https://doi.org/10.3390/geosciences8030084
Received: 26 October 2017 / Revised: 1 February 2018 / Accepted: 26 February 2018 / Published: 1 March 2018
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Abstract
This study used stable hydrogen and oxygen isotopes as natural tracers to investigate their isotopic composition in precipitation, and in shallow and deep groundwater in the Penghu Islands in the Taiwan Strait. We aimed to understand the differences and relationships in isotope compositions
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This study used stable hydrogen and oxygen isotopes as natural tracers to investigate their isotopic composition in precipitation, and in shallow and deep groundwater in the Penghu Islands in the Taiwan Strait. We aimed to understand the differences and relationships in isotope compositions within various water bodies and to evaluate the source of groundwater recharge. The hydrogen and oxygen isotopic compositions of sampled groundwater are mainly distributed along the meteoric water line in the Penghu Islands, the variations in the distribution range being minor (the δD values are distributed from −48.2‰ to −37.7‰, with a mean value of −43.14 ± 2.4‰; the δ18O values are distributed from −6.96‰ to −5.46‰, with a mean value of −6.34 ± 0.34‰). The data suggest that the groundwater is sourced mainly from local precipitation. In addition, a comparison of the hydrogen and oxygen isotopic compositions of groundwater and precipitation in Taiwan shows that the δ values for groundwater are distributed between those for precipitation during the northeast monsoon and the southwest monsoon seasons. However, some of the δ values trends towards the isotopic composition of the precipitation during the southwest monsoon season. Thus, the source of groundwater may have a closer association with precipitation during this time. Full article
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Open AccessArticle Optimum Design of Curved Surface Sliders Based on Site-Specific Seismic Input and Its Sensitivity
Geosciences 2018, 8(3), 83; https://doi.org/10.3390/geosciences8030083
Received: 20 January 2018 / Revised: 21 February 2018 / Accepted: 22 February 2018 / Published: 27 February 2018
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Abstract
The design of curved surface sliders (CSS) based on the elastic response spectrum method with site-specific seismic input is commonly made by trial and error, whereby the design does not necessarily minimize structural acceleration. This paper therefore describes the optimum CSS design for
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The design of curved surface sliders (CSS) based on the elastic response spectrum method with site-specific seismic input is commonly made by trial and error, whereby the design does not necessarily minimize structural acceleration. This paper therefore describes the optimum CSS design for minimum structural acceleration for given site-specific seismic input. All valid CSS designs and the optimum CSS design are represented by their associated trajectory in the elastic response spectrum plane that visualizes the optimization problem. The results demonstrate that the optimum CSS design is not obtained at maximum tolerated effective damping ratio. The subsequent sensitivity analysis describes how much the structural acceleration increases if the actual friction coefficient of the real CSS deviates from its optimum design value. The analysis points out that the increase in structural acceleration is approximately one order of magnitude smaller than the deviation in friction. The sensitivity data may be used by structural engineers to determine tolerable deviations in friction coefficient ensuring acceptable structural accelerations. Full article
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Open AccessArticle Sand Dune Albedo Feedback
Geosciences 2018, 8(3), 82; https://doi.org/10.3390/geosciences8030082
Received: 11 December 2017 / Revised: 22 January 2018 / Accepted: 13 February 2018 / Published: 27 February 2018
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Abstract
Sand dunes cover substantial parts of desert areas. Fully active dunes are bare, while fixed dunes are stabilized by vegetation and biogenic crust, and the dune activity is affected by the wind. Here we suggest the following atmosphere-sand dune feedback: spatial differences in
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Sand dunes cover substantial parts of desert areas. Fully active dunes are bare, while fixed dunes are stabilized by vegetation and biogenic crust, and the dune activity is affected by the wind. Here we suggest the following atmosphere-sand dune feedback: spatial differences in the dunes’ vegetation and biogenic crust cover lead to differences in albedo as the albedo of bare sand is larger than that of vegetation and biogenic crust. This leads to a higher temperature over the vegetated area, resulting in air flow from the bare dune area to the vegetated dune area, thus increasing the wind activity over the vegetated dune area. In turn, this leads to enhanced stress on the vegetation and enhanced dune activity and thus to a decrease in vegetation. These changes in vegetation cover affect the surface albedo, leading to a change in wind activity. We examined this feedback using an atmospheric general circulation model, Weather Research and Forecasting (WRF), in selected regions of the northwestern Negev Desert and the Sahara/Sahel region, and we show that changes in surface albedo do indeed lead to significantly enhanced wind activity over the lower albedo region. We then incorporated this feedback into a simple vegetated dune model, showing that the multiple states associated with active and fixed dunes can be obtained for a larger range of parameters and that the stables states become more extreme (i.e., the fixed dune state becomes more vegetated and the active dune state becomes less vegetated). Full article
(This article belongs to the Special Issue Aeolian Processes and Geomorphology)
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Open AccessArticle Comparison of the Performance of Six Drought Indices in Characterizing Historical Drought for the Upper Blue Nile Basin, Ethiopia
Geosciences 2018, 8(3), 81; https://doi.org/10.3390/geosciences8030081
Received: 17 October 2017 / Revised: 22 February 2018 / Accepted: 22 February 2018 / Published: 27 February 2018
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Abstract
The Upper Blue Nile (UBN) basin is less-explored in terms of drought studies as compared to other parts of Ethiopia and lacks a basin-specific drought monitoring system. This study compares six drought indices: Standardized Precipitation Index (SPI), Standardized Precipitation Evaporation Index (SPEI), Evapotranspiration
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The Upper Blue Nile (UBN) basin is less-explored in terms of drought studies as compared to other parts of Ethiopia and lacks a basin-specific drought monitoring system. This study compares six drought indices: Standardized Precipitation Index (SPI), Standardized Precipitation Evaporation Index (SPEI), Evapotranspiration Deficit Index (ETDI), Soil Moisture Deficit Index (SMDI), Aggregate Drought Index (ADI), and Standardized Runoff-discharge Index (SRI), and evaluates their performance with respect to identifying historic drought events in the UBN basin. The indices were calculated using monthly time series of observed precipitation, average temperature, river discharge, and modeled evapotranspiration and soil moisture from 1970 to 2010. The Pearson’s correlation coefficients between the six drought indices were analyzed. SPI and SPEI at 3-month aggregate period showed high correlation with ETDI and SMDI (r > 0.62), while SPI and SPEI at 12-month aggregate period correlate better with SRI. The performance of the six drought indices in identifying historic droughts: 1973–1974, 1983–1984, 1994–1995, and 2003–2004 was analyzed using data obtained from Emergency Events Database (EM-DAT) and previous studies. When drought onset dates indicated by the six drought indices are compared with that in the EM-DAT. SPI, and SPEI showed early onsets of drought events, except 2003–2004 drought for which the onset date was unavailable in EM-DAT. Similarly, ETDI, SMDI and SRI-3 showed early onset for two drought events and late onsets in one-drought event. In contrast, ADI showed late onsets for two drought events and early onset for one drought event. None of the six drought indices could individually identify the onsets of all the selected historic drought events; however, they may identify the onsets when combined by considering several input variables at different aggregate periods. Full article
(This article belongs to the Special Issue Drought Monitoring and Prediction)
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Open AccessArticle Regional Scale Sea Cliff Hazard Assessment at Sintra and Cascais Counties, Western Coast of Portugal
Geosciences 2018, 8(3), 80; https://doi.org/10.3390/geosciences8030080
Received: 15 December 2017 / Revised: 14 February 2018 / Accepted: 21 February 2018 / Published: 26 February 2018
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Abstract
Mass movements of different types and sizes are the main processes of sea cliff evolution, being a considerable natural hazard, the assessment of which is a relevant issue in terms of human loss prevention and land use regulations. To predict the occurrence of
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Mass movements of different types and sizes are the main processes of sea cliff evolution, being a considerable natural hazard, the assessment of which is a relevant issue in terms of human loss prevention and land use regulations. To predict the occurrence of future failures affecting the cliff top in slow retreating cliffs, a study was made using the logistic regression statistical method, a set of predisposing factors mainly related with geology (lithology, structure, faults), geomorphology (maximum, mean and standard variation of slope angle, height, aspect, curvatures, toe protection) and near offshore mean annual wave power, which were correlated with an aerial photo interpretation based inventory of cliff failures occurred in a 63 years period (1947–2010). The susceptibility model was validated against the inventory data using standard Receiver Operator Curves, which provided area under the curve (AUC) values higher than 0.8. In spite of the room for improvement of cliff failure inventories and predisposing factors to be used in these types of studies, namely those related to the rock mass strength and wave power nearshore, the results obtained indicate that the proposed approach is an effective contribution for objective and quantitative hazard assessment. Full article
(This article belongs to the Special Issue Natural Hazards and Risks Assessment)
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Open AccessArticle The Application of Seismic Attributes and Wheeler Transformations for the Geomorphological Interpretation of Stratigraphic Surfaces: A Case Study of the F3 Block, Dutch Offshore Sector, North Sea
Geosciences 2018, 8(3), 79; https://doi.org/10.3390/geosciences8030079
Received: 25 December 2017 / Revised: 21 February 2018 / Accepted: 23 February 2018 / Published: 26 February 2018
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Abstract
This study was carried out in the Pliocene interval of the southern North Sea F3 Block in the Netherlands. This research paper demonstrates how an integrated interpretation of geological information using seismic attributes, sequence stratigraphic interpretation and Wheeler transformation methods allow for the
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This study was carried out in the Pliocene interval of the southern North Sea F3 Block in the Netherlands. This research paper demonstrates how an integrated interpretation of geological information using seismic attributes, sequence stratigraphic interpretation and Wheeler transformation methods allow for the accurate interpretation of the depositional environment of a basin, as well as locating seismic geomorphological features. The methodology adopted here is to generate a 3D dip-steered HorizonCube followed by chronostratigraphic analysis, 3D Wheeler transformation, and system tract interpretation. A dip-steered seismic attribute (similarity, dip, and curvature) was performed on each stratigraphic surface of interest and the isopach maps were generated for each stratigraphic surface to help identify the maximum deposition. The results of this study show that the similarity attribute is able to identify distinct stratigraphic features such as sand-waves and deep marine meandering channels. However, its lateral continuity is poorly understood, as the similarity attribute does not take into account the true geological dip and curvature of the surfaces. Structural features such as faults are not easily recognizable due to these reasons. However, the dip-apparent attributes are found to be very useful in identifying both the structural and stratigraphic features. The seismic dip map is then improved by rotating the dip measurements to user-defined azimuths. Such optimization has revealed the structural and stratigraphic features that are not clearly evident on the similarity and curvature attributes. The maximum curvature attribute is found to be useful in delineating faults and predicting the orientation and distribution of fractures and also in subtle structural features. Full article
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