bluuebunny/crossref_metadata_2025 huggingface dataset:
Buckle fold growth in the western Northern Calcareous Alps fold-and-thrust belt of Austria– finite element modelling and field observations
Authors: Kilian Sinah , Ortner Hugo , Schneider-Muntau Barbara
Published: March 2020

We studied the Karwendel mountains of the Northern Calcareous Alps fold-and-thrust belt, that formed during the Upper Cretaceous. The study area exposes one of the principal thrusts that emplaces Triassic sediments on the top of Cretaceous rocks. Based on a detailed structural analysis (Kilian and Ortner, 2019) it has been demonstrated that the folds above the thrust are buckle folds.

With the finite element modelling, we aimed to create folds with wavelengths comparable to those observed in the field. The model set up is a simple layer cake model based on the stratigraphy of the western Northern Calcareous Alps. We used ABAQUS a finite element software to create the model. The material model is linear elasticity. During modelling, we tested different material characteristics and layer thickness. In all model runs a very weak décollement (possibly salt) is necessary to produce folds. We further tested the influence of erosion and re-sedimentation on the development of structures. We concluded that the growth of folds having wavelengths comparable to the field examples depends on the thickness of the competent layer, whereas the thickness of the incompetent layer has negligible influence.

We suggest that fold development in this part of the Northern Calcareous Alps is dependent on the interplay between the growth of evaporite-cored anticlines and surface erosion.

Reference

Kilian, S., Ortner, H.: Structural evidence of in-sequence and out-of-sequence thrusting in the Karwendel mountains and the tectonic subdivision of the western Northern Calcareous Alps. Austrian Journal of Earth Sciences, Vienna, 2019, V.112/1, p.62-83, DOI: 10.17738/ajes.2019.0005.
Understanding the spatio-temporal variability of soil moisture by integrating cosmic-ray neutron probes with SoilNet wireless sensor netwoks under a seasonal Mediterranean-climate regime
Authors: Nasta Paolo , Bogena Heye , Sica Benedetto , Vereecken Harry , Romano Nunzio
Published: March 2020

A Critical Zone Observatory (CZO) was recently established in the Alento River Catchment (ARC; southern Italy) within the TERENO (TERrestrial ENvironmental Observatories) long-term ecosystem infrastructure network. In 2016 SoilNet wireless sensor networks and cosmic ray neutron probes (CRNP) were installed in the upper part of this catchment and specifically in two experimental sub-catchments (MFC2 and GOR1) characterized by different topographic, pedological, land-use, and weather conditions. The Soilnet end-devices are monitoring soil moisture and matric potential at two different soil depths (15 cm and 30 cm) in 20 locations around the cosmic ray neutron probe. We evaluated the the relationship between Soil Moisture Index (SMI) and rainfall deficits (considered as rainfall minus potential evapotranspiration) at monthly time scale. The cropland site on the south-facing hillslope of ARC is characterized by more extreme dry and wet conditions. Another goal is to identify the dominant controls that most govern the spatial soil moisture patterns in these two different sites. The relationship between the CRNP-based soil moisture and spatial variability of SoilNet-based soil moisture is nearly linear in the case of the cropland site (MFC2) but follows a fairly concave curve in the case of the forestland site (GOR1). The majority of the spatial variance in MFC2 is explained by terrain attributes, i.e. slope-induced during wet conditions and aspect-induced during dry conditions. In GOR1 the spatial variance of soil moisture data is mostly explained by topographic factors under wet conditions during the rainy season. In both sites the soil texture is able to explain only less than 10% of spatial variability of soil moisture data.
Paleoclimatic reconstruction studies in lake sediments: major proxies, technical evolution and database
Authors: Bianchini Paula , Yokoyama Elder , Prado Luciana
Published: March 2020

Paleoclimate studies in different temporal and spatial scales provide important information on long-term statistics required to test hypotheses about climate changes. Comprehensive high-quality data sets and a solid understanding of dynamic climate processes in different temporal variations are essential to evaluate the sensitivity of the climatic system. Moreover, these data sets and dynamic analyses can help to distinguish the variability of natural and anthropogenic factors, reducing uncertainties about the magnitude and impact of future global climate changes. A common way to conduct paleoclimatic studies is through high resolution multiproxy lake sediments. Lake environments have been increasingly used in recent years to infer past fluctuations in climate, and many studies that comprise different locations and timescales demonstrate the great value of lakes as paleoclimatic archives. Because lake sediments are continental indicators sensitive to environmental changes, they can be used to reconstruct climate parameters, such as past rainfall, area management and environmental or limnological lake conditions. Changes of rainfall quantity can be recorded in lake archives by the variation of sedimentary input, which is related to changes in drainage basin and erosion rate. Beside of sedimentary input, lake sediments also exhibit physical and chemical changes in water bodies which, in turn, induce transformation in geochemical composition caused by changes in runoff or other allocated components. Thus, there is a variation in the proxies used in the studies, both in relation to the type of proxy used and the relationship used. In this context, we made a compilation of paleoclimatic studies on lake sediments (about 350 lakes), focusing on the main proxies used. Our study shows that there has been a change in the major proxies used along decades and with the emergence of new analysis techniques. In addition, we notice that lake characteristics (e.g., shape, geomorphological context, formation, etc.) have directly influence the proxies used and the quality of the information obtained. This compilation provides a database with an analysis of several lakes around the world, which can help future works and enable the identification of commonly used proxies according to the different variables that should be used, promoting more objective analyzes.
Analysis of surface rupture complexity sheds light on coseismic slip during the last earthquakes along the Bulnay-Tsetserleg fault zone (Mongolia)
Authors: Benjelloun Yacine , Klinger Yann , Antoine Solène , Baatarsuren Ganbold , Bollinger Laurent , Cheon Yungbeom , Choi Jin-Hyuck , Davaasuren Ganzorig
Published: March 2020

In 1905, two M ~ 8 continental strike-slip earthquakes occurred along the Bulnay fault system, in the northwestern part of Mongolia. After a first earthquake that ruptured the Tsetserleg oblique fault strand, the second event ruptured the main Bulnay fault 14 days later. With a total rupture of 676 km, these two earthquakes constitute the largest continental strike-slip earthquake sequence ever documented. Hence, the Mongolian earthquake ruptures offer a unique opportunity to document large-magnitude earthquake continental ruptures. Indeed, due to dry climatic conditions, limited erosion and anthropization, the surface ruptures have been preserved almost unaltered. This allows for accurate documentation of the rupture trace and coseismic slip distribution along the Bulnay fault, based on field observation and satellite imagery.

Along the Tsetserleg rupture, the available coseismic offset measurement data coming from high-resolution satellite imagery show a significant variability, ranging between 1.5 and 4 m for the horizontal component. It is presently difficult to assess the most representative value for the 1905 slip, which in turn impacts the magnitude estimation for this event. Another factor to take into account is the possibility of a vertical slip component, which is only poorly constrained.

In order to have a better estimate of the 3D coseismic slip, drone images were acquired on selected sites along the Bulnay 1905 rupture, near the junction with Tsetserleg fault, and along the Tsetserleg rupture. We favored sites showing structural complexities and significant surface fracture development (succession of cracks and ridges, stepovers, branching zones…).

High-resolution DEMs and orthophotomosaics were produced using the MicMac software. The geometrical characteristics of the complexities and their fracture network were then measured in order to compute the volumetric changes associated to the 1905 earthquake. These data were finally converted to 3D surface slip estimates. On certain sites, we also discussed the presence of features inherited from previous ruptures, overprinted by the 1905 earthquake.
The FOCUS experiment 2020 (Fiber Optic Cable Use for Seafloor studies of earthquake hazard and deformation)
Authors: Gutscher Marc-Andre , Royer Jean-Yves , Graindorge David , Murphy Shane , Klingelhoefer Frauke , Aiken Chastity , Cattaneo Antonio , Barreca Giovanni , Quetel Lionel , Riccobene Giorgio , Aurnia Salvatore , Petersen Florian , Lange Dietrich , Urlaub Morelia , Krastel Seabstian , Gross Felix , Kopp Heidrun , Moretti Milena , Beranzoli Laura , Lo Bue Nadia ,   FOCUS Team
Published: March 2020

Laser reflectometry (BOTDR), commonly used for structural health monitoring (bridges, dams, etc.), for the first time is being tested to study movements of an active fault on the seafloor, 25 km offshore Catania Sicily (an urban area of 1 million people). Under ideal conditions, this technique can measure small strains (10E-6), across very large distances (10 - 200 km) and locate these strains with a spatial resolution of 10 - 50 m. As the first experiment of the European funded FOCUS project (ERC Advanced Grant), in late April 2020 we aimed to connect and deploy a dedicated 6-km long strain cable to the TSS (Test Site South) seafloor observatory in 2100 m water depth operated by INFN-LNS (Italian National Physics Institute). The work plan for the marine expedition FocusX1 onboard the research vessel PourquoiPas? is described here. First, microbathymetric mapping and a video camera survey are performed by the ROV Victor6000. Then, several intermediate junction frames and short connector cables (umbilicals) are connected. A cable-end module and 6-km long fiber-optic strain cable (manufactured by Nexans Norway) is then connected to the new junction box. Next, we use a deep-water cable-laying system with an integrated plow (updated Deep Sea Net design Ifremer, Toulon) to bury the cable 20 cm in the soft sediments in order to increase coupling between the cable and the seafloor. The targeted track for the cable crosses the North Alfeo Fault at three locations. Laser reflectometry measurements began April 2020 and will be calibrated by a three-year deployment of seafloor geodetic instruments (Canopus acoustic beacons manufactured by iXblue) also started April 2020, to quantify relative displacement across the fault. During a future marine expedition, tentatively scheduled for 2021 (FocusX2) a passive seismological experiment is planned to record regional seismicity. This will involve deployment of a temporary network of OBS (Ocean Bottom Seismometers) on the seafloor and seismic stations on land, supplemented by INGV permanent land stations. The simultaneous use of laser reflectometry, seafloor geodetic stations as well as seismological land and sea stations will provide an integrated system for monitoring a wide range of types of slipping events along the North Alfeo Fault (e.g. - creep, slow-slip, rupture). A long-term goal is the development of dual-use telecom cables with industry partners.
3D Geodynamic Models of the Present-Day Altiplano-Puna Magmatic System
Authors: Spang Arne , Baumann Tobias , Kaus Boris
Published: March 2020

For the past decades, several numerical studies have successfully reproduced the concentric uplift pattern observed above the Altiplano-Puna Magma Body (APMB) in the central Andes. However, the temperature- and strain rate-dependent viscoelastoplastic rheology of rocks, the buoyancy of magma, the effects of modelling in 3D as well as the shape of the magma body have often been simplified or neglected.

Here, we use a joint interpretation of seismic imaging and gravity anomalies to constrain location, 3D shape and density of the magma body. With the help of the thermo-mechanical finite difference code LaMEM, we then model the surface deformation and test our results against observations made by Interferometric Synthetic-Aperture Radar (InSAR) missions. This way, we gain insights into the dynamics and rheology of the present-day magmatic system and can test how a change to the current conditions (e.g., magma influx) could impact it.

We find that only an APMB with a maximum thickness of 14 to 18 km and a corresponding density contrast to the surrounding host rock of 100 to 175 kg/m3 satisfies both tomography and Bouguer data. Based on that and the chemistry of eruption products, we estimate the melt content of the APMB to be on the order of 20 - 25%. We also find that the observed uplift can be reproduced by magma-induced buoyancy forces without the need for an additional pressure source or magma injection within the mush, and that the geometry of the top of the magma body exerts a major control on the deformation pattern at the surface.
Limitations of soft-sediment deformation structures as indicator for paleo-earthquakes in formerly periglacial and glaciated areas
Authors: Müller Katharina , Winsemann Jutta , Lege Thomas , Spies Thomas , Brandes Christian
Published: March 2020

During the last years many studies focused on soft-sediment deformation structures (SSDS) to identify past seismic events. However, in regions that were affected by glaciations and periglacial processes like northern and central Europe, the use of SSDS as paleo-earthquake indicator is challenging. Interpretations require great care. Earthquakes are only one possible trigger mechanism of many that can cause liquefaction and/or fluidization of sediments, which leads to the formation of e.g. sand volcanoes, clastic dykes, flame structures, or ball-and-pillow structures.

SSDS triggered by seismic shaking are so-called seismites. Originally the term ‘seismites’ was used by Sailacher (1969) and only referred to sediment beds that were deformed by earthquake-related shaking. Pleistocene seismites are described from former glaciated areas in Germany, Denmark, Sweden, Poland, Latvia, and Lithuania.

However, ice-sheet loading, glaciotectonism as well as freeze and thaw processes in periglacial environments are also potential trigger mechanisms causing the formation of similar looking types of SSDS, which can be easily mistaken for seismites. Therefore, it is important to use a set of clear criteria to recognize seismites in the field.

Extensive studies of Pleistocene sediments in northern Germany have shown that deformation bands are a suitable indicator for paleo-fault activity. Deformation bands that are developed close to the tip line of a fault in combination with e.g. sand volcanoes, clastic dykes, flame structures, or ball-and-pillow structures is the most robust indicator for paleo-earthquakes.

 

References

 Seilacher, A. (1969). Fault-graded beds interpreted as seismites. Sedimentology, 13, 155-159.
What governs the effects of permafrost thaw on boreal forest dynamics?
Authors: Kulawska Aleksandra , Pugh Thomas A. M. , Kettridge Nicholas , MacKenzie Rob , Ullah Sami
Published: March 2020

Boreal forests are located at latitudes that are predicted to experience some of the greatest warming on the planet. Forests growing on permafrost may be particularly vulnerable, with accelerated soil warming and permafrost degradation linked to changing patterns of tree growth and longevity. Many have speculated that thawing permafrost, through its effects on soil water content and ground stability, will increase forest mortality across the boreal region. However, recent evidence indicates mixed forest responses to permafrost thaw. In some areas, the onset of thaw is followed by increased tree growth and increased forest cover area. In other sites, thaw has been linked to decreased growth and forest cover loss. It is currently poorly understood what determines these contrasting responses, and the roles that different environmental and climatic factors may play. This leads to two major issues: (1) uncertainties in predicting the effects of future permafrost thaw on carbon dynamics in northern ecosystems, and (2) poor understanding of where scientific and conservation efforts should be focused. Here, we present a review of the recent evidence of permafrost thaw effects on boreal forest dynamics and propose an explanation for the differing responses across sites. We argue that the outcome is controlled by a set of factors that influence two major pathways and the interactions between them: (1) permafrost-soil water content and (2) soil water content-plant growth. We present a series of conceptual models explaining these interactions and highlight the largest sources of uncertainties. Based on these, we propose a set of hypotheses and methodologies to guide future research in this area.
Local diagnostics of Rossby wave packet properties – Seasonal variability and their role in temperature extremes
Authors: Fragkoulidis Georgios , Wirth Volkmar
Published: March 2020

Transient Rossby wave packets (RWPs) are a prominent feature of the synoptic to planetary upper-tropospheric flow at the mid-latitudes. This prompts the development of diagnostic methods to identify and investigate the spatiotemporal evolution of key RWP properties. Such properties include the RWP phase speed and group velocity, the diagnosis of which has so far remained non-local in space and/or time. To this end, a novel diagnostic approach is presented here, which is based on the analytic signal of upper-tropospheric meridional wind velocity and thus allows the evaluation of RWP properties locally in space and time. The detailed insight into these properties can be utilized toward a better understanding of the upper-tropospheric circulation, its interplay with local weather features, and its model representation. In particular, climatologies of RWP amplitude, wavenumber, phase speed, and group velocity are investigated using reanalysis data for the time period 1979 – 2018. Pronounced features of seasonal and interregional variability are highlighted. Moreover, the role of RWP amplitude and phase speed in the occurrence and duration of temperature extremes in Europe is explored. Finally, indications of systematic biases in medium-range forecasts of these fields suggest that a correct representation of the RWP evolution is crucial for the predictability of temperature extreme events.
Reprocessing, depth conversion and structural restoration of vintage seismic data: New insights into the volcano-tectonic evolution of the Christiana-Santorini-Kolumbo marine volcanic zone
Authors: Huebscher Christian , Preine Jonas
Published: March 2020

Located on the Hellenic Volcanic Arc, the Christiana-Santorini-Kolumbo (CSK) marine volcanic zone is notorious for its catastrophic volcanic eruptions, earthquakes and tsunamis. Here, not only the largest volcanic eruption in human history, the so-called “Minoan” eruption took place in the Late Bronze age 3600 years ago, but also the largest 20th-century shallow earthquake in Europe of magnitude 7.4 in 1956. Although the region is heavily populated and a fully developed touristic region, the acting tectonic forces are not fully understood to this day aggravating the necessary assessment of geohazards.

Recent bathymetric and seismic studies revealed that the CSK zone comprises a system of neotectonic horst and graben structures with extended internal faulting that is thought to be the result of the ongoing extension in the southern Aegean. The NE-SW alignment of volcanic edifices within the CSK underlines the tectonic control of volcanism in this area. In this study, we show how advanced reprocessing of selected seismic lines leads to significantly improved seismic images revealing new details of the complex rift system. Moreover, using a unique diffraction-based approach for velocity model building, we perform pre-stack depth migration (PSDM) and present for the first time depth-converted seismic sections from the CSK zone. This allows for the proper estimation of fault angles, sedimentary thicknesses and performing structural restoration in order to reconstruct and measure the amount of extension in the individual rift basins. We revise the previous seismostratigraphic scheme and propose a new correlation between the horst and graben units.

Structural restoration indicates an extension of approx. 3 km along the Santorini-Anafi basin while PSDM indicates the sedimentary strata to be of maximum 1500 m thickness. According to the new stratigraphic model, we infer a four-stage evolution of this basin in which early marine deposition, syn-rift deposition, complex infill deposition and neotectonic syn-rift deposition are distinguished. Moreover, we identify negative flower structures within the basin centre indicating the presence of a strike-slip component, which superimposes the dominant NW-SE directed extension. Based on these findings, we are confident that by applying the proposed workflow to the complete regional dataset, the understanding of the relationship between tectonics and volcanism in the CSK zone will be significantly improved, and, consequently, will lead to an improved risk assessment of the central Aegean Sea.
Twelve years of SIFTER Sun-Induced Fluorescence retrievals from GOME-2 as an independent constraint on photosynthesis across continents and biomes
Authors: Kooreman Maurits L. , Boersma K. Folkert , van Schaik Erik , Mengistu Anteneh G. , Tuinder Olaf N. E. , Stammes Piet , Koren Gerbrand , Peters Wouter
Published: March 2020

Solar-Induced Fluorescence (SIF) data from satellites are increasingly used as a proxy for photosynthetic activity by vegetation, and as a constraint on gross primary production. The Royal Netherlands Meteorological Institute has developed an improved retrieval algorithm called SIFTER, to retrieve mid-morning (09:30 hrs local time) SIF estimates on the global scale from GOME-2 sensors on the Metop satellite series. The product is developed within the ACSAF network of EUMETSAT and a beta version is publicly available on www.temis.nl. The SIFTER algorithm improves over a previous version by using a narrower spectral window that avoids strong oxygen absorption and is less sensitive to water vapor absorption, by constructing stable reference spectra from a 6-year period (2007-2012) of atmospheric spectra over the Sahara, and by applying a latitude-dependent zero-level adjustment that accounts for biases in the product data. With SIFTER, we generate stable, good-quality SIF retrievals also in tropical regions that are known to suffer from high noise in other SIF products. Uncertainty estimates are included for individual observations, and the product is best used for mostly clear-sky scenes, and when spectral residuals remain below a certain threshold. The strength of SIFTER in the tropical regions was exploited to quantify the 2015/2016 drought in the Amazon, related to El Niño. We found that SIF was strongly suppressed over areas with anomalously high temperatures and decreased levels of soil moisture. SIF went below its climatological range starting from the end of the 2015 dry season and returned to normal levels by February 2016. A validation study is performed to assess the SIFTER quality against independent SIF and GPP products from other platforms, including SIF from OCO-2 and GOSAT, modeled GPP from MPI-BGC and eddy covariance derived, in-situ GPP measurements. SIFTER shows strong correlations (0.70 – 0.94) in the zonal distribution for each continent and in capturing seasonal patterns of SIF and GPP over different regions across the globe (0.62-0.99) when comparing to OCO-2 SIF and GPP from MPI-BGC. At ecosystem level, SIFTER was evaluated against OCO-2 SIF and EC GPP for five flux tower sites with varying biomes and geolocations. Regions with a homogeneous vegetation distribution show a higher correlation than heterogeneous regions. Overall, the results support the use of SIFTER data to be used as an independent constraint on photosynthetic activity on global and regional scales.
Comparing 18 precipitation datasets for large scale distributed hydrological modelling
Authors: Brandimarte Luigia , Mazzoleni Maurizio , Amaranto Alessandro
Published: March 2020

Our understanding of the advantages and limitations of satellite derived precipitation datasets as a forcing to hydrological models has made tremendous progress over the past decade. However, most studies have only analysed the performance of one or few datasets, have used global precipitation datasets to force lumped models on regional/large-scale basins, or have adopted more complex distributed models but applied them to small basin scales.

We aimed at addressing these gaps in the literature: in particular, we compared the performance of 18 different precipitation datasets used as input in a grid-based distributed hydrological model to assess streamflow in large-scale river basins. These datasets are classified as Uncorrected Satellites, Corrected Satellites, and Reanalysis-Gauges based datasets. The hydrological model is applied to 8 large scale river basins (Amazon, Brahmaputra, Congo, Danube, Godavari, Mississippi, Rhine and Volga) with different sizes, presence of hydraulic structures, human footprint, hydrometeorological characteristics, and precipitation gauge network density were selected.

The results of this study showed that there is not a unique best performing precipitation dataset for all basins and results are very sensitive to the basin characteristics. However, there are few datasets which persistently outperform the others: SM2RAIN-ASCAT for Class 1, CHIRPS V2.0, MSWEP V2.1, and CMORPH-CRTV1.0 for Class 2, GPCC and WFEDEI GPCC for Class 3. The use of a distributed modelling approach rather than lumped is supported by the fact that precipitation datasets showing the highest model result at the basin outlet do not show the same high performance at internal locations of the basin. In addition, precipitation datasets belonging to Class 2 outperform the other datasets in basins with Tropical and Temperate-Arid climate (e.g. Congo, Mississippi and Godavari), while Class 3 datasets show the highest NSE values in Temperate and Temperate-Cold basins (e.g. Danube, Rhine and Volga).
Efficient Calibration of a Global Tide and Surge Model
Authors: wang xiaohui , Verlaan Martin , Lin Hai Xiang
Published: March 2020

Combined tide and surge models are very useful tools to issue warnings for storm surges as well as for assessment of the potential impacts of sealevel rise. Over the past decade, a Global Tide and Surge Model (GTSM) has been developed by Deltares with improvements in physics, grid resolution and skill in the each new version. The uncertainties in bathymetry and friction are currently a major part of the remaining model uncertainty. Improved estimates of these parameters would be desirable, but the required computing speed and memory storage are limiting the possibilities at the moment. Here, we propose an efficient coarse grid parameter estimation scheme for the high resolution GTSM to estimate the bathymetry. OpenDA software is combined with GTSM using DUD algorithm (Does not Use Derivative) making use of the FES2014 dataset as observations in deep water. Even though parallel computing is implemented for model simulation, calibration of the fine grid model directly would still require too much computer time, for instance, e.g. it takes 9 hours on 20 cores to simulate 45 days and calibration typically requires many of these simulations. Therefore, a coarse-to-fine strategy is developed by replacing the fine grid with coarse grid in parameter estimation iterations to reduce the computing cost by 67%. Moreover, via a sensitivity analysis we are able to reduce the parameter dimension from O(106) to O(102) which leads to a  further reduction of the required computation and memory. The results of the estimation and model validation demonstrate the parameter estimation scheme to improve the accuracy of the model by approximately 30% with affordable computational and storage demands.

 
High-resolution DEM Creation using a UAV for Flood Inundation Hydrodynamic Modeling- A Case of Rel River Flood, Gujarat, India
Authors: Patel Dhruvesh , Dave Raviraj , Dubey Amit Kumar , Gupta Praveen Kumar , Singh Raghavendra
Published: March 2020

Catastrophic flood leads to a major disaster in developing countries. It loses a life and significant valuable properties, therefore it assessment is a prime requirement to identify the risk and vulnerable area in a flood-prone region. Many hydrodynamic models are providing a solution to identify the flood inundation area, flood arrival time, and velocity of flow in flood susceptible area, however, due to the low resolution of DEM, it can’t assess the actual flooding condition. To overcome this limitation, the present study describes the creation of high resolution (3 cm gridded) DEM for Dhanera city, Rel river catchment in Gujarat where it was affected by the catastrophic flood in the year of 2015 and 2017. Phantom 4 Pro RTK, DGPS and Pix4 software are used for creation of high-resolution DEM. The entire 10 km2 area of Dhanera city is divided 4 blocks and each block is mapped by Phantom 4 pro-RTK Unmanned Aerial Vehicle (UAV) at 80 % image overlaps. A total of 9222 images are captured and post-processed using a Pix 4 software. Ground Control Points were marked for rectification in the geo-location of aerial images using DGPS (RTK). The aerial images collected during the survey have a spatial resolution of 3 cm with geo-location. The data collected is put for post-processing using Pix4D mapper software. 3D classified point cloud, DTM and DSM of 3 cm spatial resolution, orthomosaic of 3 cm spatial resolution are produced after the processing. Generated High-resolution DEM (DTM & DSM) will be utilized for hydrodynamic modeling to produce a precise flood inundation maps. 

 

Acknowledgement: The corresponding author is thankful to the ORSP, PDPU, and SAC-ISRO, SARITA program for providing the research grant to execute the work. (Grant no: ORSP/R&D/SRP/2019/MPDP/007; SAC/EPSA/GHCAG/LHD/SARITA/01/19)
Slip-dependent weakening revealed for a shallow megasplay fault in the Nankai subduction zone
Authors: Roesner Alexander , Ikari Matt , Huepers Andre , Kopf Achim
Published: March 2020

The Nankai Trough megasplay fault likely hosts different modes of fault slip, from slow to megathrust earthquakes, and is responsible for related phenomena such as tsunamis and submarine landslides. All types of slip events require some kind of frictional weakening process (e.g. slip and/or velocity weakening) in order to nucleate and propagate. Most frictional earthquake studies analyze the velocity dependence of friction but disregard the slip dependence of friction observed in experimental friction studies.

We tested fluid-saturated powdered megasplay fault samples from Integrated Ocean Drilling Program Site C0004 in a direct shear apparatus under effective normal stresses from 2 – 18 MPa to investigate the velocity- and slip-dependence of friction of the megasplay fault. For every tested effective normal stress, we performed one velocity-step experiment and two constant velocity experiments (no velocity step). In the velocity-step experiments the samples were sheared to a total displacement of 10 mm, with an initial sliding velocity V0 = 0.1 µm/s for the first ~5 mm (run-in) followed by a velocity step increase to V = 1.0 µm/s over the last 5 mm. During the constant velocity experiments, the shearing velocity (0.1 and 1.0 µm/s respectively) was held constant for 10 mm of displacement.

The velocity-stepping tests showed an evolution from velocity weakening at low effective normal stresses to velocity strengthening at high effective normal stresses. All experiments revealed strong slip-weakening behavior, with the slip dependence having a much larger effect on friction than the velocity dependence. The friction slip dependence is also controlled by the effective normal stress, showing large weakening rate at low effective normal stresses and smaller weakening rate at higher effective normal stresses. Therefore, both frictional weakening mechanisms on the megasplay fault become more effective at shallow depths. This may amplify seafloor deformation by shallow coseismic slip and could increase the tsunamigenic potential of the fault zone.
Zenith Troposphere Delay Prediction based on BP Neural Network and Least Squares Support Vector Machine
Authors: Xu Tianhe , Li Song , Jiang Nan
Published: March 2020

Abstract: With the rapid development of artificial intelligence, machine learning has become an high-efficient tool applied in the fields of GNSS data analysis and processing, such as troposphere, ionosphere or satellite clock modeling and prediction. In this paper, zenith troposphere delay (ZTD) prediction algorithms based on BP neural network (BPNN) and least squares support vector machine (LSSVM) are proposed in the time and space domain. The main trend terms in ZTD time series are deducted by polynomial fitting, and the remaining residuals are reconstructed and modeled by BPNN and LSSVM algorithm respectively. The test results show that the performance of LSSVM is better than that of BPNN in term of prediction stability and accuracy by using ZTD products of International GNSS Service (IGS) of 20 stations in time domain. In order to further improve LSSVM prediction accuracy, a new strategy of training samples selection based on correlation analysis is proposed. The results show that using the proposed strategy, about 80% to 90% of the 1-hour prediction deviation of LSSVM can reach millimeter level depending on the season, and the percentage of the prediction deviation value less than 5 mm is about 60% to 70%, which is 5% to 20% higher than that of the classical random selection in different month. The mean values of RMSE in all 20 stations using the new strategy are 1-3mm smaller than those of the classical one. Then different prediction span from 1 to 12 hours is conducted to show the performance of the proposed method. Finally, the ZTD predictions based on BPNN and LSSVM in space domain are also verified and compared using GNSS CORS network data of Hong Kong, China.

Keywords: ZTD, BP Neural Network, Support Vector Machine, Least Squares, GNSS

Acknowledgments: This work was supported by Natural Science Foundation of China (41874032) and the National Key Research and Development Program (2016YFB0501701)

 
A probability model of three potential precursors during tornado occurrences: the Italian case.
Authors: Ingrosso Roberto , Lionello Piero , Miglietta Mario Marcello , Salvadori Gianfausto
Published: March 2020

57 tornadoes with intensity Enhanced Fujita Scale 2 or larger that occurred in Italy in the period 2000–2018 are analysed in order to investigate the way two meteorological parameters, namely Wind Shear, calculated in 0-1 km and 0-6 km layers, and CAPE, affect their development. For this purpose, a statistical analysis, by means of homogeneity tests, conditional probabilities and a multivariate analysis via copulas is performed, using two different re-analysis datasets (ERA-Interim and ERA-5). The study indicates that: (a) tornadoes occur mostly in correspondence with positive anomalies of both variables; (b) probability of occurrence is correlated with WS, and (c) is maximum when either WS or CAPE are large. Also, the probability does not increase significantly with CAPE, although sufficiently large values are needed for tornado occurrence. These results are similar for both re-analyses we used and suggest that the selected parameters are reliable precursors for Italian tornadoes.
Aquatic ecosystems in Miocene western Amazonia – marine ingressions vs. salt leaching
Authors: Piller Werner , Gross Martin
Published: March 2020

Before the onset of the modern Amazon river system, north-western South America was shaped by an extensive wetland during the Miocene. This ‘Pebas mega-wetland’ kept a well renowned endemic mollusk and ostracod fauna, which initiated a persisting debate about marine ingressions reaching the center of Amazonia at that time. Due to high endemism, uniformitarian principles are hardly applicable to this biota but also other paleontological, sedimentological and geochemical information led to ambiguous paleoenvironmental interpretations. These results are based on ostracod and foraminiferal assemblages and the oxygen and carbon stable isotopy of their biogenic calcite from an outcrop at the cutbank of the Amazon river (NE-Peru, ~55 km S of Iquitos). While ostracods (e.g., Cyprideis) are able to calcify their carapaces along the entire salinity range, at least low saline conditions are a prerequisite for the biomineralization of calcareous foraminiferan tests. Hence, the finding of calcareous foraminifers (Ammonia, Elphidium), associated mainly with brackish water ostracods, indicates the presence of saline waters. In contrast, δ18O- and δ13C-analyses performed on co-occurring ostracod valves and foraminiferan tests yielded constantly very light ratios. Such values refer to a pure freshwater environment and are incompatible with the interference of isotopically heavier, marine waters or an evaporative stable isotope enrichment. Based on these opposing data, we hypothesize that the Pebas mega-wetland was episodically influenced by mineralized but isotopically light groundwater discharge. Possibly, the resulting specific hydrochemistry contributed not only to the evolution of the endemic Pebasian fauna but also facilitated the sporadic settlement of euryhaline foraminifers, which mimics short-lived marine incursions.
Long term seismic hazard information from intact, vulnerable stalagmites in Domica cave, O:rdo:glik Hall, Slovakia
Authors: Gribovszki Katalin , Pinti Daniele , Shen Chuan-Chou , Mónus Péter , Prácser Ernő , Novák Attila , Kiszely Márta , Esterhazy Sofi , Czirok Lili , Lednicka Marketa
Published: March 2020

Long-term information can be gained from intact and vulnerable stalagmites in natural caves. These formations survived all earthquakes that have occurred, over thousands of years - depending on the age of the stalagmite. Their “survival” requires that the horizontal ground acceleration has never exceeded a certain critical value within that time period.

Here we present such a stalagmite-based case study from the Gömör-Torna karst region, Slovakia. A candlestick shaped, intact and vulnerable 4.51 m tall stalagmite in Domica cave, Ördöglik Hall has been examined in situ many times since 2012. The examination of candlestick shaped, intact and vulnerable (IVSTM) in Domica cave, Ördöglik Hall (southeastern Slovakia) is the continuation of our previous examination of intact, vulnerable stalagmites in other caves in Hungary, Bulgaria, Slovakia and Austria. The aim of our investigation is to estimate the upper limit for horizontal peak ground acceleration generated by paleoearthquakes.

The method of our investigation is the same as before: the density, the Young’s modulus and the tensile failure stress of broken stalagmite samples have been measured in mechanical laboratory, whereas the dimensions and the natural frequency of IVSTM were determined by in situ observations. The value of horizontal ground acceleration resulting in failure and the theoretical natural frequency of IVSTM were assessed by theoretical calculations.

New results of age determination of drilled core samples from Ördöglik Hall, Domica cave are available. The age has been determined by Multi Collector – Inductively Coupled Plasma Mass Spectrometry analysis (MC-ICPMS). Our measurements show, that the base part of the IVSTM is not older than 10 kyears.

The critical horizontal ground acceleration values as a function of time going back into the past determined from stalagmite, that we investigated (IVSTM), are presented. This result have to be taken into account when calculating the seismic potential of faults near to Domica cave (e.g. Darnó and Rozsnyó lines).
How does the magnetosphere go to sleep?
Authors: Moretto Jorgensen Therese , Hesse Michael , Rastaetter Lutz , Vennerstrom Susanne , Tenfjord Paul
Published: March 2020

Energy and circulation in the Earth’s magnetosphere and ionosphere are largely determined by conditions in the solar wind and interplanetary magnetic field. When the driving from the solar wind is turned off (to a minimum), we expect the activity to die down but exactly how this happens is not known.  Utilizing global MHD modelling, we have addressed the questions of what constitutes the quietest state for the magnetosphere and how it is approached following a northward turning in the IMF that minimizes the driving. We observed an exponential decay with a decay time of about 1 hr in several integrated parameters related to different aspects of magnetospheric activity, including the total field-aligned current into and out of the ionosphere.  The time rate of change for the cessation of activity was also measured in total field aligned current estimates from the AMPERE project, adding observational support to this finding.  Events of distinct northward turnings of the interplanetary magnetic field were identified, with prolonged periods of stable southward driving conditions followed by northward interplanetary magnetic field conditions. A well-defined exponential decay could be identified in the total hemispheric field-aligned current following the northward turning with a generic decay constant of 0.9, corresponding to an e-folding time of 1.1 hr. A possible physical explanation for the exponential decay follows from considering what needs to happen for the convection in the magnetosphere to slow down, or stop, namely the unwinding of the field-aligned current carrying flux tubes in the coupled magnetosphere-ionosphere system. A statistical analysis of the ensemble of events also reveals both a seasonal and a day/night variation in the decay parameter, with faster decay observed in the winter than in the summer hemisphere and on the nightside than on the dayside. These results can be understood in terms of stronger/weaker line tying of the ionospheric foot points of magnetospheric field lines for higher/lower conductivity.  Additional global modeling results with varying conductance scenarios for the ionosphere confirm this interpretation.   
Data-based machine learning unveils ecosystem metabolic regimes at the scale of entire stream networks
Authors: Segatto Pier Luigi , Battin Tom J. , Bertuzzo Enrico
Published: March 2020

Inland waters are major contributors to the global carbon cycle. Nowadays, new sensor technology has changed the way we study ecosystem metabolism in streams. We are able to produce long-term time series of gross primary production (GPP) and ecosystem respiration (ER) to infer drivers of the stream ecosystem metabolic regime and its seasonal timing. Despite big data availability, most studies are limited to individual stream reaches and do not allow the appreciation of metabolic regimes at the scale of entire networks, which, however, would be fundamental to properly assess the relevance of metabolic fluxes within streams and rivers for carbon cycling at the regional and global scale. Machine learning (ML) has great potential in this direction. Firstly, ML could be used to extrapolate both in time and space heterogeneous forcings (e.g., streamwater temperature (T) and photosynthetic active radiation (PAR)) required to run a process-based model for reach-scale metabolism to the scale of an entire stream network. Secondly, the same procedure could be applied to reach-scale estimates of ecosystem metabolism to check whether available data contain enough information to explain the network scale variability. In this study, we used Random Forest to predict patterns of environmental forcings (T and PAR) and stream metabolism (GPP and ER) at the scale of an entire stream network. We used available high-frequency measurements of T and PAR, estimates of ecosystem metabolism and major proximal controls (e.g., incident light, discharge, stream-bed slope, drainage area, water level,  air temperature) from twelve reaches within the Ybbs River network (Austria) and explicitly trained our Random Forests by integrating distal factors, namely:  vegetation type, canopy cover, hydro-geomorphic properties, light,  precipitation, and other climatic variables. We designed two different training setups to assess spatial and temporal predicting model capabilities, respectively. This approach allowed us to reliably infer the target variables (T, PAR, GPP, and ER) on annual basis across a stream network, to filter the most important predictors, to assess the relative contribution of the metabolic fluxes from small to large streams, to estimate annual metabolic budgets at different spatial scales and to provide empirical evidence for long-standing theory predicting shifts of ecosystem metabolism along the stream continuum. Finally, we estimated autochthonous and allochthonous respiration for the entire stream network, which is crucial to integrate the role of ecosystem processes for the carbon cycle.
Evapotranspiration, water demand and water footprint of urban green spaces
Authors: Nouri Hamideh , Chavoshi Borujeni Sattar , Hoekstra Arjen
Published: March 2020

The world’s population residing in urban areas grew from 30% in 1950 to about 60% in 2020 and is expected to reach 68% by 2050. As urban areas continue to grow, green spaces in cities are getting ever more treasured. Most cities have adopted strategies to be greener to improve their resilience and livability. To make the best of the benefits offered by urban green spaces, healthy greenness is essential and this means additional water consumption. Water limitation usually results in drying out of green areas in summer, when benefits and services by green spaces are highly demanded (e.g. cooling effect). In the 21st century, vulnerability to water shortage is not restricted to dry regions anymore;  water scarcity in the time of need is threatening the livability of cities even in wet regions (i.e. extreme summers in Europe). In this study, we estimate for the first time, to our knowledge, the blue water consumption of urban green spaces. We measure the evapotranspiration of an urban green space using three approaches of in-situ, observational-based and remote sensing, and employ principles of water footprint. We assess the blue and green water footprint of urban greenery to maintain green areas of a city based on their water demand, not the abstracted water or irrigated water. In the case of Adelaide Parklands in Australia, the annual total water footprint is 1114mm, of which 17% consumes in spring, 42% in summer, 27% in autumn, and 14% in winter. The average blue water footprint of the Parklands calculates 0.66 m3 per square meter per annum. The hot and dry summer causes a high total water footprint compared to the cold and wet winter. This study is transferable to other cities for quantification of blue water consumption of urban green spaces and their water footprint. These findings may help to guide urbanisation priorities to move toward greening cities with no extra pressure on scarce water resources.