Open AccessArticle
Legacy Lead from Past Mining Activity and Gasoline Additives: Evidence from Lead Isotopes and Trace Element Geochemical Studies in the White River Basin, Southern Ozark Region, USA
Geosciences 2018, 8(6), 189; https://doi.org/10.3390/geosciences8060189 (registering DOI) -
Abstract
Lead isotope compositions and Pb, Cu, Zn, and As concentrations in stream sediment leachates in the White River Basin, southern Ozark Region, have been determined to discriminate between natural and anthropogenic sources of Pb and to assess the metal loads that are transported
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Lead isotope compositions and Pb, Cu, Zn, and As concentrations in stream sediment leachates in the White River Basin, southern Ozark Region, have been determined to discriminate between natural and anthropogenic sources of Pb and to assess the metal loads that are transported by streams draining the Mississippi Valley-type (MVT) Zn-Pb mines in the Northern Arkansas district. The samples that were collected downstream of and closest to the mines have trace element concentrations well above those in soils from Arkansas. The trace element concentrations are lower in samples that were collected upstream of the mines. Most of the analyzed samples have trace metal concentrations above the United States Environmental Protection Agency (USEPA) Sediment Quality Guidelines Threshold Effects Level. The Pb isotope values of the downstream samples and the MVT ores are similar, suggesting a similar Pb source. The Pb isotope values of the upstream samples are similar to those that were defined by soils from the Ozark Plateau, suggesting that Pb from historic mining does not dominate upstream sediments. However, a linear regression line through the leachate data indicates that mixing between two end-members represented by leaded gasoline and ores could generate the Pb isotope ratios that were noticed in the upstream leachates. Full article
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Open AccessArticle
Bathymetry and Canyons of the Eastern Bering Sea Slope
Geosciences 2018, 8(5), 184; https://doi.org/10.3390/geosciences8050184 -
Abstract
We created a new, 100 m horizontal resolution bathymetry raster and used it to define 29 canyons of the eastern Bering Sea (EBS) slope area off of Alaska, USA. To create this bathymetry surface we proofed, edited, and digitized 18 million soundings from
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We created a new, 100 m horizontal resolution bathymetry raster and used it to define 29 canyons of the eastern Bering Sea (EBS) slope area off of Alaska, USA. To create this bathymetry surface we proofed, edited, and digitized 18 million soundings from over 200 individual sources. Despite the vast size (~1250 km long by ~3000 m high) and ecological significance of the EBS slope, there have been few hydrographic-quality charting cruises conducted in this area, so we relied mostly on uncalibrated underway files from cruises of convenience. The lack of hydrographic quality surveys, anecdotal reports of features such as pinnacles, and reliance on satellite altimetry data has created confusion in previous bathymetric compilations about the details along the slope, such as the shape and location of canyons along the edge of the slope, and hills and valleys on the adjacent shelf area. A better model of the EBS slope will be useful for geologists, oceanographers, and biologists studying the seafloor geomorphology and the unusually high productivity along this poorly understood seafloor feature. Full article
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Open AccessArticle
Georeferenced Agricultural Data for Statistical Reuse
Geosciences 2018, 8(5), 188; https://doi.org/10.3390/geosciences8050188 -
Abstract
The guidelines to the Public Sector Information (PSI) Directive states: “opening up public sector information (PSI) for reuse brings major socioeconomic benefits”, which has been recognised in various domains. However, the reuse may be limited due to organisational and technical reasons. This study
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The guidelines to the Public Sector Information (PSI) Directive states: “opening up public sector information (PSI) for reuse brings major socioeconomic benefits”, which has been recognised in various domains. However, the reuse may be limited due to organisational and technical reasons. This study addresses the collaboration between the statistical and the agricultural domain using the example of the Integrated Administration and Control System (IACS) and the Integrated Farm Statistics (IFS). After the comparison of the spatial data requirements in IACS and IFS, a conceptual collaboration model was developed that makes clear how the challenges of interoperability can be resolved by technical arrangements and work organisation. Full article
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Open AccessArticle
Selected Metal Content and Binding Behaviour in Riverbed Sediments of the Kavala–Philippi Area (Northern Greece)
Geosciences 2018, 8(5), 187; https://doi.org/10.3390/geosciences8050187 -
Abstract
The broader Philippi area (NE Macedonia, Northern Greece), which was chosen for the present study, is characterized by the presence of various metals. An approach to the correlation of selected parameters (grain-size distribution, Al2O3, CaO, Fe2O3
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The broader Philippi area (NE Macedonia, Northern Greece), which was chosen for the present study, is characterized by the presence of various metals. An approach to the correlation of selected parameters (grain-size distribution, Al2O3, CaO, Fe2O3, MnO, SiO2 content, environmentally available concentrations of Cu and Zn) was carried out in samples collected downstream of Palea Kavala River and Kryoneri and Philippi streams. The abundance of Cu, Fe, Mn, and Zn in relation to four binding fractions (exchangeable, bound to carbonates, Fe–Mn oxides, organic matter complexes) was also investigated. The enrichment of the studied metals was determined by evaluating the enrichment factor (EF) and geo-accumulation index (Igeo). Considering the results, Si was the most abundant major element oxide in sediments, followed by Al, Ca, Fe, and Mn. The sediments are dominated by sand and reveal minor Cu and Fe enrichment and moderate Mn and Zn enrichment. Statistical analyses revealed a significant correlation between Cu, Fe, Mn, and Zn, suggesting their common sources. They probably originate naturally, since the weathering of metal assemblages occurring in the broader Philippi area, comprising minerals such as chalcopyrite, pyrite, goethite, pyrolusite and sphalerite, may contribute to the concentrations of these elements in the sediments. Full article
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Open AccessArticle
Fatalities Caused by Hydrometeorological Disasters in Texas
Geosciences 2018, 8(5), 186; https://doi.org/10.3390/geosciences8050186 -
Abstract
Texas ranks first in the U.S in number of fatalities due to natural disasters. Based on data culled from the National Oceanic and Atmospheric Administration (NOAA) from 1959 to 2016, the number of hydrometeorological fatalities in Texas have increased over the 58-year study
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Texas ranks first in the U.S in number of fatalities due to natural disasters. Based on data culled from the National Oceanic and Atmospheric Administration (NOAA) from 1959 to 2016, the number of hydrometeorological fatalities in Texas have increased over the 58-year study period, but the per capita fatalities have significantly decreased. Spatial review found that non-coastal flooding is the predominant hydrometeorological disaster in a majority of the Texas counties located in “Flash Flood Alley” and accounts for 43% of all hydrometeorological fatalities in the state. Flooding fatalities occur most frequently on “Transportation Routes” followed by heat fatalities in “Permanent Residences”. Seasonal and monthly stratification identifies Spring and Summer as the deadliest seasons, with the month of May registering the highest number of total fatalities dominated by flooding and tornado fatalities. Demographic trends of hydrometeorological disaster fatalities indicated that approximately twice as many male fatalities occurred from 1959-2016 than female fatalities, but with decreasing gender disparity over time. Adults are the highest fatality risk group overall, children are most at risk to die in flooding, and the elderly at greatest risk of heat-related death. Full article
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Open AccessArticle
Experimental Modelling of the Caprock/Cement Interface Behaviour under CO2 Storage Conditions: Effect of Water and Supercritical CO2 from a Cathodoluminescence Study
Geosciences 2018, 8(5), 185; https://doi.org/10.3390/geosciences8050185 -
Abstract
In the framework of CO2 geological storage, one of the critical points leading to possible important CO2 leakage is the behaviour of the different interfaces between the rocks and the injection wells. This paper discussed the results from an experimental modelling
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In the framework of CO2 geological storage, one of the critical points leading to possible important CO2 leakage is the behaviour of the different interfaces between the rocks and the injection wells. This paper discussed the results from an experimental modelling of the evolution of a caprock/cement interface under high pressure and temperature conditions. Batch experiments were performed with a caprock (Callovo-Oxfordian claystone of the Paris Basin) in contact with a cement (Portland class G) in the presence of supercritical CO2 under dry or wet conditions. The mineralogical and mechanical evolution of the caprock, the Portland cement, and their interface submitted to the attack of carbonic acid either supercritical or dissolved in a saline water under geological conditions of pressure and temperature. This model should help to better understand the behaviour of interfaces in the proximal zone at the injection site and to prevent risks of leakage from this critical part of injection wells. After one month of ageing at 80 °C under 100 bar of CO2 pressure, the caprock, the cement, and the interface between the caprock and cement are investigated with Scanning Electron Microscopy (SEM) and cathodoluminescence (CL). The main results reveal (i) the influence of the alteration conditions: with dry CO2, the carbonation of the cement is more extended than under wet conditions; (ii) successive phases of carbonate precipitation (calcite and aragonite) responsible for the loss of mechanical cohesion of the interfaces; (iii) the mineralogical and chemical evolution of the cement which undergoes successive phases of carbonation and leaching; (iv) the limited reactivity of the clayey caprock despite the acidic attack of CO2; and (v) the influence of water on the transport mechanisms of dissolved species and thus on the location of mineral precipitations. Full article
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Open AccessArticle
Rock Magnetic, Petrography, and Geochemistry Studies of Lava at the Ijen Volcanic Complex (IVC), Banyuwangi, East Java, Indonesia
Geosciences 2018, 8(5), 183; https://doi.org/10.3390/geosciences8050183 -
Abstract
Lava has complex geochemical characteristics based on differences in eruption centers, eruptive events, and flow emplacement. Characterization of lava is useful for understanding the geological conditions of a volcanic region. To complement geochemical methods, rock magnetic methods are being used to analyze lava.
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Lava has complex geochemical characteristics based on differences in eruption centers, eruptive events, and flow emplacement. Characterization of lava is useful for understanding the geological conditions of a volcanic region. To complement geochemical methods, rock magnetic methods are being used to analyze lava. To explore the potential uses of rock magnetic methods for lava characterization, a series of magnetic measurements were completed in lava samples from eight locations in the Ijen Volcanic Complex (IVC) in Banyuwangi, East Java, Indonesia. These locations were grouped into two eruption centers: Ijen Crater and Mount Anyar. The magnetic measurements included frequency-dependent magnetic susceptibility, thermomagnetic, anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM), and hysteresis curve analyses. These measurements were supplemented using X-ray fluorescence, petrography analyses, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). Based on their lithology, lava samples were categorized into basalt, basaltic andesite, and basaltic trachyandesite. The dominant magnetic mineral contained in the sample was iron-rich titanomagnetite and titanium-rich titanomagnetite with a magnetic pseudo-single-domain and small amounts of superparamagnetic grain minerals in some samples. The significant difference in mass specific susceptibility (χLF) is caused by differences in the crystallization process. The differences in susceptibility frequency dependence (χFD) highlighted the differences in the magma cooling rate, demonstrated by the differences in the percentage of opaque mineral groundmass. The rock magnetic method was proven to support the geochemistry and petrography methods used to characterize lava and identify the causes of differences in lava characteristics. Full article
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Open AccessArticle
HF/VHF Radar Sounding of Ice from Manned and Unmanned Airborne Platforms
Geosciences 2018, 8(5), 182; https://doi.org/10.3390/geosciences8050182 -
Abstract
Ice thickness and bed topography of fast-flowing outlet glaciers are large sources of uncertainty for the current ice sheet models used to predict future contributions to sea-level rise. Due to a lack of coverage and difficulty in sounding and imaging with ice-penetrating radars,
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Ice thickness and bed topography of fast-flowing outlet glaciers are large sources of uncertainty for the current ice sheet models used to predict future contributions to sea-level rise. Due to a lack of coverage and difficulty in sounding and imaging with ice-penetrating radars, these regions remain poorly constrained in models. Increases in off-nadir scattering due to the highly crevassed surfaces, volumetric scattering (due to debris and/or pockets of liquid water), and signal attenuation (due to warmer ice near the bottom) are all impediments in detecting bed-echoes. A set of high-frequency (HF)/very high-frequency (VHF) radars operating at 14 MHz and 30–35 MHz were developed at the University of Kansas to sound temperate ice and outlet glaciers. We have deployed these radars on a small unmanned aircraft system (UAS) and a DHC-6 Twin Otter. For both installations, the system utilized a dipole antenna oriented in the cross-track direction, providing some performance advantages over other temperate ice sounders operating at lower frequencies. In this paper, we describe the platform-sensor systems, field operations, data-processing techniques, and preliminary results. We also compare our results with data from other ice-sounding radars that operate at frequencies both above (Center for Remote Sensing of Ice Sheets (CReSIS) Multichannel Coherent Depth Sounder (MCoRDS)) and below (Jet Propulsion Laboratory (JPL) Warm Ice Sounding Explorer (WISE)) our HF/VHF system. During field campaigns, both unmanned and manned platforms flew closely spaced parallel and repeat flight lines. We examine these data sets to determine image coherency between flight lines and discuss the feasibility of forming 2D synthetic apertures by using such a mission approach. Full article
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Open AccessArticle
From Deterministic to Probabilistic Forecasts: The ‘Shift-Target’ Approach in the Milan Urban Area (Northern Italy)
Geosciences 2018, 8(5), 181; https://doi.org/10.3390/geosciences8050181 -
Abstract
The number of natural catastrophes that affect people worldwide is increasing; among these, the hydro-meteorological events represent the worst scenario due to the thousands of deaths and huge damages to private and state ownership they can cause. To prevent this, besides various structural
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The number of natural catastrophes that affect people worldwide is increasing; among these, the hydro-meteorological events represent the worst scenario due to the thousands of deaths and huge damages to private and state ownership they can cause. To prevent this, besides various structural measures, many non-structural solutions, such as the implementation of flood warning systems, have been proposed in recent years. In this study, we suggest a low computational cost method to produce a probabilistic flood prediction system using a single forecast precipitation scenario perturbed via a spatial shift. In fact, it is well-known that accurate forecasts of heavy precipitation, especially associated with deep moist convection, are challenging due to uncertainties arising from the numerical weather prediction (NWP), and high sensitivity to misrepresentation of the initial atmospheric state. Inaccuracies in precipitation forecasts are partially due to spatial misplacing. To produce hydro-meteorological simulations and forecasts, we use a flood forecasting system which comprises the physically-based rainfall-runoff hydrological model FEST-WB developed by the Politecnico di Milano, and the MOLOCH meteorological model provided by the Institute of Atmospheric Sciences and Climate (CNR-ISAC). The areas of study are the hydrological basins of the rivers Seveso, Olona, and Lambro located in the northern part of Milan city (northern Italy) where this system works every day in real-time. In this paper, we show the performance of reforecasts carried out between the years 2012 and 2015: in particular, we explore the ‘Shift-Target’ (ST) approach in order to obtain 40 ensemble members, which we assume equally likely, derived from the available deterministic precipitation forecast. Performances are shown through statistical indexes based on exceeding the threshold for different gauge stations over the three hydrological basins. Results highlight how the Shift-Target approach complements the deterministic MOLOCH-based flood forecast for warning purposes. Full article
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Open AccessArticle
A Hybrid Empirical Green’s Function Technique for Predicting Ground Motion from Induced Seismicity: Application to the Basel Enhanced Geothermal System
Geosciences 2018, 8(5), 180; https://doi.org/10.3390/geosciences8050180 -
Abstract
A method is described for the prediction of site-specific surface ground motion due to induced earthquakes occurring in predictable and well-defined source zones. The method is based on empirical Green’s functions (EGFs), determined using micro-earthquakes at sites where seismicity is being induced (e.g.,
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A method is described for the prediction of site-specific surface ground motion due to induced earthquakes occurring in predictable and well-defined source zones. The method is based on empirical Green’s functions (EGFs), determined using micro-earthquakes at sites where seismicity is being induced (e.g., hydraulic fracturing and wastewater injection during shale oil and gas extraction, CO2 sequestration, and conventional and enhanced geothermal injection). Using the EGF approach, a ground-motion field (e.g., an intensity map) can be calculated for a potentially felt induced event originating within the seismic zone. The approach allows site- and path-specific effects to be mapped into the ground-motion field, providing a local ground-motion model that accounts for wave-propagation effects without the requirement of 3D velocity models or extensive computational resources. As a test case, the ground-motion field for the mainshock (ML = 3.4, M = 3.2) resulting from the Basel Enhanced Geothermal System (EGS) was simulated using only seismicity recorded prior to the event. We focussed on peak ground velocity (PGV), as this is a measure of ground motion on which Swiss norms for vibration disturbances are based. The performance of the method was significantly better than a previously developed generic ground-motion prediction equation (GMPE) for induced earthquakes and showed improved performance through intrinsic inclusion of site-specific effects relative to predictions for a local GMPE. Both median motions and the site-to-site ground-motion variability were captured, leading to significantly reduced misfit relative to the generic GMPE. It was shown, however, that extrapolation beyond units of a couple of magnitude leads to significant uncertainty. The method is well suited to a real-time predictive hazard framework, for which shaking estimates are dynamically updated in light of newly recorded seismicity. Full article
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Open AccessArticle
Metadata Life Cycles, Use Cases and Hierarchies
Geosciences 2018, 8(5), 179; https://doi.org/10.3390/geosciences8050179 -
Abstract
The historic view of metadata as “data about data” is expanding to include data about other items that must be created, used, and understood throughout the data and project life cycles. In this context, metadata might better be defined as the structured and
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The historic view of metadata as “data about data” is expanding to include data about other items that must be created, used, and understood throughout the data and project life cycles. In this context, metadata might better be defined as the structured and standard part of documentation, and the metadata life cycle can be described as the metadata content that is required for documentation in each phase of the project and data life cycles. This incremental approach to metadata creation is similar to the spiral model used in software development. Each phase also has distinct users and specific questions to which they need answers. In many cases, the metadata life cycle involves hierarchies where latter phases have increased numbers of items. The relationships between metadata in different phases can be captured through structure in the metadata standard, or through conventions for identifiers. Metadata creation and management can be streamlined and simplified by re-using metadata across many records. Many of these ideas have been developed to various degrees in several Geoscience disciplines and are being used in metadata for documenting the integrated life cycle of environmental research in the Arctic, including projects, collection sites, and datasets. Full article
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Open AccessArticle
Hazard Assessment of Storm Events for the Portuguese Northern Coast
Geosciences 2018, 8(5), 178; https://doi.org/10.3390/geosciences8050178 -
Abstract
Coastal zones currently face severe weaknesses and are subject to high-risk situations. Tropical storm events can contribute to the occurrence of these high-risk situations by causing storm surges with high water levels and, consequently, episodes of wave-overtopping and coastal flooding. This work considers
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Coastal zones currently face severe weaknesses and are subject to high-risk situations. Tropical storm events can contribute to the occurrence of these high-risk situations by causing storm surges with high water levels and, consequently, episodes of wave-overtopping and coastal flooding. This work considers a series of storm scenarios and analyzes their impacts through numerical modeling. Firstly, historical storm tracks and intensities are characterized for the Portuguese northern coast in terms of probability of occurrence. Secondly, several storm events with a high potential of occurrence are generated using a specific tool of the DelftDashboard interface for Delft3D software. Hydrodynamic models are then used to generate an ensemble of simulations to assess the storms’ effects on coastal water levels. Based on the statistical data of the numerical modeling results, a synthesis of the coastal storms’ impacts at different locations within the study area is performed. Depending on the storm category, surge heights can reach 1.10 m above tide levels under simulated conditions on the Portuguese northwestern coast. Full article
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Open AccessArticle
Towards a New Paradigm in Water Management: Cochabamba’s Water Agenda from an Ethical Approach
Geosciences 2018, 8(5), 177; https://doi.org/10.3390/geosciences8050177 -
Abstract
The Cochabamba Water War (2000) is well renowned for being a part of the civil society versus water service delivery debate. From a situation of service privatization, limited access, and an inexistent institutional framework in 2000, the current situation in the Cochabamba Valley
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The Cochabamba Water War (2000) is well renowned for being a part of the civil society versus water service delivery debate. From a situation of service privatization, limited access, and an inexistent institutional framework in 2000, the current situation in the Cochabamba Valley faces increasing water scarcity within a weak institutional set up. To alleviate the situation, the government of Evo Morales has been actively funding projects considering an Integrated Water Resources Management (IWRM) but confronting customary water rights in rural communities and thus increasing the level of conflict between water uses. Amid these two water management practices appears the Agenda del Agua Cochabamba (AdA)—the Cochabamba Water Agenda—claiming water as part of the commons and not a resource. This paper explains the paradigm’s values behind the conflicting IWRM and water rights’ water management practices and analyses the AdA under a governability framework identifying the barriers and drivers for its implementation. Full article
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Open AccessArticle
Low Cost, Lightweight Gravity Coring and Improved Epoxy Impregnation Applied to Laminated Maar Sediment in Vietnam
Geosciences 2018, 8(5), 176; https://doi.org/10.3390/geosciences8050176 -
Abstract
In response to the need for lightweight and affordable sediment coring and high-resolution structural documentation of unconsolidated sediment, we developed economical and fast methods for (i) recovering short sediment cores with undisturbed topmost sediment, without the need for a firmly anchored coring platform,
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In response to the need for lightweight and affordable sediment coring and high-resolution structural documentation of unconsolidated sediment, we developed economical and fast methods for (i) recovering short sediment cores with undisturbed topmost sediment, without the need for a firmly anchored coring platform, and (ii) rapid epoxy-impregnation of crayon-shaped subcores in preparation for thin-sectioning, with minimal use of solvents and epoxy resin. The ‘Autonomous Gravity Corer’ (AGC) can be carried to remote locations and deployed from an inflatable or makeshift raft. Its utility was tested on modern unconsolidated lacustrine sediment from a ~21 m deep maar lake in Vietnam’s Central Highlands near Pleiku. The sedimentary fabric fidelity of the epoxy-impregnation method was demonstrated for finely laminated artificial flume sediment. Our affordable AGC is attractive not only for work in developing countries, but lends itself broadly for coring in remote regions where challenging logistics prevent the use of heavy coring equipment. The improved epoxy-impregnation technique saves effort and costly chemical reagents, while at the same time preserving the texture of the sediment. Full article
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Open AccessArticle
Numerically Calculated 3D Space-Weighting Functions to Image Crustal Volcanic Structures Using Diffuse Coda Waves
Geosciences 2018, 8(5), 175; https://doi.org/10.3390/geosciences8050175 -
Abstract
Seismic coda measurements retrieve parameters linked to the physical characteristics of rock volumes illuminated by high frequency scattered waves. Space weighting functions (SWF) and kernels are different tools that model the spatial sensitivity of coda envelopes to scattering and absorption anomalies in these
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Seismic coda measurements retrieve parameters linked to the physical characteristics of rock volumes illuminated by high frequency scattered waves. Space weighting functions (SWF) and kernels are different tools that model the spatial sensitivity of coda envelopes to scattering and absorption anomalies in these rock matrices, allowing coda-wave attenuation ( Qcoda ) imaging. This note clarifies the difference between SWF and sensitivity kernels developed for coda wave imaging. It extends the SWF previously developed in 2D to the third dimension by using radiative transfer and the diffusion equation, based on the assumption that variations of Qcoda depend solely on variations of the extinction length. When applied to active data (Deception Island, Antarctica), 3D SWF images strongly resemble 2D images, making this 3D extension redundant. On the other hand, diffusion does not efficiently model coda waveforms when using earthquake datasets spanning depths between 0 and 20 km, such as at Mount St. Helens volcano. In this setting, scattering attenuation and absorption suffer tradeoffs and cannot be separated by fitting a single seismogram energy envelope for SWF imaging. We propose that an approximate analytical 3D SWF, similar in shape to the common coda kernels used in literature, can still be used in a space weighted back-projection approach. While Qcoda is not a physical parameter of the propagation medium, its spatially-dependent modeling allows improved reconstruction of crustal-scale tectonic and geological features. It is even more efficient as a velocity independent imaging tool for magma and fluid storage when applied to deep volcanism. Full article
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Open AccessArticle
Mapping the Loss of Mt. Kenya’s Glaciers: An Example of the Challenges of Satellite Monitoring of Very Small Glaciers
Geosciences 2018, 8(5), 174; https://doi.org/10.3390/geosciences8050174 -
Abstract
Since the last complete glacier mapping of Mt. Kenya in 2004, strong glacier retreat and glacier disintegration have been reported. Here, we compile and present a new glacier inventory of Mt. Kenya to document recent glacier change. Glacier area and mass changes were
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Since the last complete glacier mapping of Mt. Kenya in 2004, strong glacier retreat and glacier disintegration have been reported. Here, we compile and present a new glacier inventory of Mt. Kenya to document recent glacier change. Glacier area and mass changes were derived from an orthophoto and digital elevation model extracted from Pléiades tri-stereo satellite images. We additionally explore the feasibility of using freely available imagery (Sentinel-2) and an alternative elevation model (TanDEM-X-DEM) for monitoring very small glaciers in complex terrain, but both proved to be inappropriate; Sentinel-2 because of its too coarse horizontal resolution compared to the very small glaciers, and TanDEM-X-DEM because of errors in the steep summit area of Mt. Kenya. During 2004–2016, the total glacier area on Mt. Kenya decreased by 121.0 × 10³ m² (44%). The largest glacier (Lewis) lost 62.8 × 10³ m² (46%) of its area and 1.35 × 10³ m³ (57%) of its volume during the same period. The mass loss of Lewis Glacier has been accelerating since 2010 due to glacier disintegration, which has led to the emergence of a rock outcrop splitting the glacier in two parts. If the current retreat rates prevail, Mt. Kenya’s glaciers will be extinct before 2030, implying the cessation of the longest glacier monitoring record of the tropics. Full article
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Open AccessArticle
Systematic Evaluation of Different Infrastructure Systems for Tsunami Defense in Sendai City
Geosciences 2018, 8(5), 173; https://doi.org/10.3390/geosciences8050173 -
Abstract
The aim of this study is to assess the performances of different infrastructures as structural tsunami countermeasures in Sendai City, based on the lessons from the 11 March 2011, Great East Japan Tsunami, which is an example of a worst-case scenario. The tsunami
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The aim of this study is to assess the performances of different infrastructures as structural tsunami countermeasures in Sendai City, based on the lessons from the 11 March 2011, Great East Japan Tsunami, which is an example of a worst-case scenario. The tsunami source model Ver. 1.2 proposed by Tohoku University uses 10 subfaults, determined based on the tsunami height and the run-up heights measured for all tsunami affected areas. The TUNAMI-N2 model is used to simulate 24 cases of tsunami defense in Sendai City based on a combination of 5 scenarios of structural measures, namely, a seawall (existing and new seawall), a greenbelt, an elevated road and a highway. The results of a 2D tsunami numerical analysis show a significant difference in the tsunami inundations in the areas protected by several combinations of structures. The elevated road provides the highest performance of the single schemes, whereas the highest performance of the 2-layer schemes is the combination of an existing seawall and an elevated road. For the 3-layer scenarios, the highest performance is achieved by the grouping of an existing seawall, a new seawall, and an elevated road. The combination of an existing seawall, a new seawall, a greenbelt and an elevated road is the highest performing 4-layer scenario. The Sendai City plan, with a 5-layer scenario, reduces the tsunami inundation area by 20 sq. km with existing structural conditions. We found that the combination of an existing seawall, a greenbelt, an elevated road and a highway (a 4-layer scheme) is the optimum case to protect the city against a tsunami similar to the 2011 Great East Japan Tsunami. The proposed approach can be a guideline for future tsunami protection and the evaluation of countermeasure schemes. Full article
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Open AccessArticle
Multicamera, Multimethod Measurements for Hydromorphologic Laboratory Experiments
Geosciences 2018, 8(5), 172; https://doi.org/10.3390/geosciences8050172 -
Abstract
The realization of hydromorphologic laboratory experiments on the propagation of aggrading or degrading sediment fronts requires simultaneous measurements of the sediment feeding rate, the profile of the free surface, and the flume bed elevation. In this study, five action cameras and different image-processing
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The realization of hydromorphologic laboratory experiments on the propagation of aggrading or degrading sediment fronts requires simultaneous measurements of the sediment feeding rate, the profile of the free surface, and the flume bed elevation. In this study, five action cameras and different image-processing techniques were employed to measure all the needed quantities automatically and with adequate temporal resolution. The measurement of the sediment feeding rate was determined by particle image velocimetry as a surrogate, correlated quantity: the surface velocity of the sediment flow along a vibrating channel was used as an upstream feeder. The profile of the free surface was measured by shooting an array of piezometers connected to the flume. Each piezometer pipe contained a buoyant black sphere that could be recognized by using tools for particle identification, thus determining the elevation of the free surface above the piezometric probe. Finally, the bed profile along the flume was measured at any instant by edge detection, locating the transition from a water layer to a sediment layer in images taken from the side of the flume. The paper describes the instrumentation and the methods, finally presenting the results obtained from a prototypal experiment. Potentialities and limitations of the proposed methods are discussed, together with some prospects on future use in systematic experimental campaigns. Full article
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Open AccessReview
Role of Aeolian Dust in Shaping Landscapes and Soils of Arid and Semi-Arid South Africa
Geosciences 2018, 8(5), 171; https://doi.org/10.3390/geosciences8050171 -
Abstract
The deposition of fine aeolian sediment profoundly influences the morphology of several different landscapes of the arid and semi-arid western portion of South Africa. Such landscapes and features include: (1) regularly-spaced mounds known as heuweltjies of the succulent Karoo region, (2) barren stone
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The deposition of fine aeolian sediment profoundly influences the morphology of several different landscapes of the arid and semi-arid western portion of South Africa. Such landscapes and features include: (1) regularly-spaced mounds known as heuweltjies of the succulent Karoo region, (2) barren stone pavements in the more arid regions, and (3) hillslopes with smooth, curvilinear slope profiles that are mantled with coarse, stony colluvium. Investigations of each of these are presented, together with comparisons of similar features found within arid and semi-arid portions of Western North America. Recent findings suggest that the formation of the distinct, regularly-spaced heuweltjies involves a linked set of biological and physical processes. These include nutrient accumulation by termites and the production of dense vegetation patches, which, in turn, serve as a trap for aeolian sediments. Dust deposition is also responsible for the formation of stone pavements as demonstrated by research conducted principally in the Mojave Desert region of the United States. Mineralogical and geochronological studies have demonstrated that the stone clasts remain on the surface as fine aeolian sediments are translocated downward beneath the clasts resulting in a silt-rich soil horizon directly beneath the clasts. Pavements examined in South Africa have the same morphological features that can only be explained by the same process. The formation of soils on hillslopes mantled with stony colluvium are commonly viewed as having formed through the in-situ weathering of the stony colluvium. However, like pavements, mantles of coarse, stony colluvium are effective dust traps that provide the long-term stability required for advanced development of thick, fine-grained soils. This process contributes to the evolution of smooth, vegetated, curvilinear slope profiles. In each of these examples, the accumulation of dust has a profound influence, not only in soil formation, but also on the development of dominant landform characteristics. A greater awareness of these processes will contribute considerably to the growth of knowledge about soils and landscape development in the drylands of South Africa. Full article
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Open AccessArticle
Development of Three-Dimensional Soil-Amplification Analysis Method for Screening for Seismic Damage to Buried Water-Distribution Pipeline Networks
Geosciences 2018, 8(5), 170; https://doi.org/10.3390/geosciences8050170 -
Abstract
A soil-amplification analysis method is developed that uses high-resolution ground data and a three-dimensional nonlinear dynamic finite-element method to screen for possible areas of seismic damage to buried water-distribution pipeline networks. The method is applied to a cut-and-fill developed area in Japan, whose
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A soil-amplification analysis method is developed that uses high-resolution ground data and a three-dimensional nonlinear dynamic finite-element method to screen for possible areas of seismic damage to buried water-distribution pipeline networks. The method is applied to a cut-and-fill developed area in Japan, whose water-distribution pipeline network was severely damaged in the 2011 off the Pacific Coast of Tohoku Earthquake. The obtained soil amplification is compared with known points of pipeline damage to check the validity of the analysis. A sensitivity test is also conducted to account for uncertainties in the properties of the ground material. From the results, it is expected that the developed soil-amplification method could be used to screen for possible damage to buried pipelines in a given area, and used to support methods for estimating damage to buried pipelines based on observations and seismic indices. Full article
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