Preprints
Filtering by Subject: Earth Sciences
Including Earth-structure uncertainties in nonlinear moment-tensor estimations
Published: 2020-05-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquake-source parameters can be estimated from seismic waveforms. Since these data indirectly observe the deformation process, parameters of a physical model that quantifies the deformation process are inferred through the inverse problem; which is under-determined. This requires several assumptions to be made about Earth structure and other aspects that affect the source parameter [...]
Optimal processing for seismic noise correlations
Published: 2020-05-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A wide spectrum of processing schemes is commonly applied during the calculation of seismic noise correlations. This is intended to suppress large-amplitude transient and monochromatic signals, to accelerate convergence of the correlation process, or to modify raw correlations into more plausible approximations of inter-station Greens functions. Many processing schemes, such as one-bit [...]
Displacement accumulation during paleoearthquakes for active normal faults on the eastern Mediterranean island of Crete
Published: 2020-05-25
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Active normal faults on the eastern Mediterranean island of Crete form prominent limestone scarps together with basin and range topography. These faults mainly strike E-ESE and N-NNE in southern and northern Crete, respectively, with fault sets commonly intersecting and northern-trending faults a factor of three more abundant. Displacements, lengths and displacement rates have been analysed for [...]
Fate of intertidal microphytobenthos nitrogen under enhanced nutrient availability: Evidence for reduced nitrogen retention revealed through 15N-labeling
Published: 2020-05-25
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics
Sediment microbial communities are an important sink for both organic and inorganic nitrogen (N), with microphytobenthos (MPB) biomass having the largest contribution to short-term N-assimilation and retention. Coastal waters are increasingly subject to anthropogenic nutrient enrichment, but the effect of this nutrient enrichment on microbial assimilation, processing, and fate of MPB-derived N [...]
Shining light on priming in euphotic sediments: Nutrient enrichment stimulates export of stored organic matter
Published: 2020-05-25
Subjects: Biogeochemistry, Earth Sciences, Life Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Estuarine sediments are important sites for the interception, processing and retention of organic matter, prior to its export to the coastal oceans. Stimulated microbial co-metabolism (priming) potentially increases export of refractory organic matter through increased production of hydrolytic enzymes. By using the microphytobenthos community to directly introduce a pulse of labile carbon into [...]
Predictive modelling of envelope flood extents using geomorphic and climatic-hydrologic catchment characteristics
Published: 2020-05-25
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Hydraulic Engineering, Hydrology, Physical Sciences and Mathematics
A topographic index (flood descriptor) that combines the scaling of bankfull depth with morphology was shown to describe the tendency of an area to be flooded. However, this approach depends on the quality and availability of flood maps and assumes that outcomes can be directly extrapolated and downscaled. This work attempts to relax these problems and answer two questions: 1) Can functional [...]
UNSEEN trends: Detecting decadal changes in 100-year precipitation extremes
Published: 2020-05-25
Subjects: Atmospheric Sciences, Civil and Environmental Engineering, Climate, Earth Sciences, Engineering, Environmental Sciences, Hydrology, Meteorology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Sample sizes of observed climate extremes are typically too small to reliably constrain non-stationary behaviour. To facilitate detection of non-stationarities in 100-year precipitation values over a short period of 35 years (1981-2015), we apply the UNprecedented Simulated Extreme ENsemble (UNSEEN) approach, by pooling ensemble members and lead times from the ECMWF seasonal prediction system [...]
Preservation of Organic Carbon in Dolomitized Cambrian Stromatolites and Implications for Microbial Biosignatures in Diagenetically Replaced Carbonate Rock
Published: 2020-05-25
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Planetary Geology, Planetary Sciences
Stromatolites have been a major focus in the search for ancient microbial life, however, the organic carbon biosignatures of dolomitized stromatolites have not yet been fully characterized or correlated with their dolomitizing conditions. Although dolomitization rarely preserves microbial morphology, the presence of organic carbon can provide valuable information for characterization of fossils’ [...]
Stress Recovery for the Particle-in-cell Finite Element Method
Published: 2020-05-25
Subjects: Applied Mathematics, Computer Sciences, Earth Sciences, Geophysics and Seismology, Mathematics, Numerical Analysis and Computation, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Tectonics and Structure
The interelement stress in the Finite Element Method is not continuous in nature, and stress projections from quadrature points to mesh nodes often causes oscillations. The widely used particle-in-cell method cannot avoid this issue and produces worse results when there are mixing materials of large strength (e.g., viscosity in Stokes problems) contrast in one element. The post-processing methods [...]
Simultaneous fall and flow during pyroclastic eruptions: a novel proximal hybrid facies.
Published: 2020-05-24
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
The deposits of Plinian and sub-Plinian eruptions provide critical insights into past volcanic events and inform numerical models that aim to mitigate against future hazards. However, pyroclastic deposits are often considered from either a fallout or pyroclastic density current (PDC) perspective, with little attention given to facies exhibiting characteristics of both processes. Such hybrid units [...]
60 YEARS OF AIRBORNE AFMAG METHOD EVOLUTION
Published: 2020-05-24
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Geotechnical Engineering, Physical Sciences and Mathematics
Development and following commercial use of the airborne electromagnetic method based on natural fields in the audio-frequency band (AFMAG) started in late 50s of the last century. After several decades of the development downtime, limitations inherent to the method were resolved in 80s by adapting the tensor analysis, remote reference noise bias removal techniques and computation of the tippers. [...]
Hidden Stories: Topic Modeling in Hydrology Literature
Published: 2020-05-24
Subjects: Artificial Intelligence and Robotics, Computer Sciences, Earth Sciences, Hydrology, Library and Information Science, Physical Sciences and Mathematics, Social and Behavioral Sciences
Hydrologic research generates large volumes of peer-reviewed literature across a number of evolving sub-topics. It’s becoming increasingly difficult for scientists and practitioners to synthesize this full body of literature. This study explores topic modeling as a form of unsupervised learning applied to 42,154 article-abstracts from six high-impact (Impact Factor > 0.9) journals (Water [...]
Automated Seismic Source Characterisation Using Deep Graph Neural Networks
Published: 2020-05-24
Subjects: Artificial Intelligence and Robotics, Computer Sciences, Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Most seismological analysis methods require knowledge of the geographic location of the stations comprising a seismic network. However, common machine learning tools used in seismology do not account for this spatial information, and so there is an underutilised potential for improving the performance of machine learning models. In this work, we propose a Graph Neural Network (GNN) approach that [...]
River sediment geochemistry as a conservative mixture of source regions: Observations and predictions from the Cairngorms, UK
Published: 2020-05-24
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The elemental composition of sediments in rivers is the product of physical and chemical erosion of rocks, which is then transported across drainage networks. A corollary is that fluvial sedimentary geochemistry can be used to understand geologic, climatic and geomorphic processes. We develop a simple methodology to predict elemental compositions of river sediments from digital elevation data and [...]
Sensitivity of evapotranspiration deficit index to its parameters and temporal scales
Published: 2020-05-24
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Physical Sciences and Mathematics, Water Resource Management
Sound estimates of drought characteristics are very important for planning intervention measures in drought-prone areas. Among many drought indices used in estimation of drought characteristics in many parts of the world, evapotranspiration deficit index (ETDI) is increasingly used to estimate agricultural drought. However, in most studies ETDI has been computed using the specific ETDI formula. [...]