Preprints
Filtering by Subject: Earth Sciences
Simultaneous fall and flow during pyroclastic eruptions: a novel proximal hybrid facies.
Published: 2020-05-25
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: 2020-05-25
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: 2020-05-25
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: 2020-05-25
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: 2020-05-25
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: 2020-05-25
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. [...]
The off-fault deformation on the North Anatolian Fault Zone and assessment of slip rate from carbonate veins
Published: 2020-05-25
Subjects: Earth Sciences, Engineering, Life Sciences, Physical Sciences and Mathematics, Tectonics and Structure
In the easternmost segment of the North Anatolian Fault (NAF) zone there are discrepancies in earthquake characteristics arising from differences between geodetically determined and geologically observed slip rates. We investigated the spatial distribution of deformation across a NAF fault segment, Turkey. Field observations were conducted on the offset of physiographic features along the [...]
Cave airflow patterns control calcite dissolution rates within a cave stream: Blowing Springs Cave, Arkansas, USA
Published: 2020-05-25
Subjects: Earth Sciences, Environmental Sciences, Geochemistry, Geomorphology, Hydrology, Physical Sciences and Mathematics
Erosion rates within streams vary dramatically over time, as differences in discharge and sediment load enhance or inhibit erosion processes. Within cave streams, and other bedrock channels incising soluble rocks, changes in water chemistry are an important factor in determining how erosion rates will vary in both time and space. Prior studies within surface streams, springs, and caves suggest [...]
Upper mantle mush zones beneath low melt flux ocean island volcanoes: insights from Isla Floreana, Galápagos
Published: 2020-05-25
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Volcanology
The physicochemical characteristics of sub-volcanic magma storage regions have important implications for magma system dynamics and pre-eruptive behaviour. The architecture of magma storage regions located directly above high buoyancy flux mantle plumes (such as Kīlauea, Hawai’i and Fernandina, Galápagos) are relatively well understood. However, far fewer constraints exist on the nature of magma [...]
Quantification and interpretation of the climate variability record
Published: 2020-05-25
Subjects: Applied Mathematics, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
This paper is currently in review for Global and Planetary Change. \\ The spectral view of variability is a compelling and adaptable tool for understanding variability of the climate. In the Mitchell (1976) seminal paper, it was used to express, on one graph with log scales, a very wide range of climate variations from millions of years to days. The spectral approach is particularly useful for [...]
Deep ductile shear localization facilitates near-orthogonal strike-slip faulting in a thin brittle lithosphere
Published: 2020-05-25
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Some active fault systems comprise near-orthogonal conjugate strike-slip faults, as highlighted by the 2019 Ridgecrest and the 2012 Indian Ocean earthquake sequences. In conventional failure theory, orthogonal faulting requires a pressure-insensitive rock strength, which is unlikely in the brittle lithosphere. Here, we conduct 3D numerical simulations to test the hypothesis that near-orthogonal [...]
Fault-controlled base-of-scarp deposits
Published: 2020-05-25
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
The term base-of-scarp is proposed for those submarine deposits controlled by a fault and physically disconnected from their more proximal counterpart located on the footwall, although genetically linked to it. These systems differ from conventional fault-controlled deltas, such as shoal- and Gilbert-type, because they are entirely subaqueous and lack equilibrium morphology — a steady-state in [...]
The influence of spreading rate and permeability on melt focusing beneath mid-ocean ridges
Published: 2020-05-25
Subjects: Earth Sciences, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics
At mid-ocean ridges, oceanic crust is emplaced in a narrow neovolcanic region on the seafloor, whereas basaltic melt that forms this oceanic crust is generated in a wide region beneath as suggested by a few geophysical surveys. The combined observations suggest that melt generated in a wide region at depths has to be transported horizontally to a small region at the surface. We present results [...]
On the thermo-poro-mechanics of chemically active faults
Published: 2020-05-21
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Geophysics and Seismology, Geotechnical Engineering, Physical Sciences and Mathematics
Shear zones in outcrops and core drillings on active faults commonly reveal two scales of localization, with centimeter to tens of meters thick deformation zones embedding much narrower zones of mm- to cm-scale. The narrow zones are often attributed to some form of fast instability such as earthquakes or slow slip events. Surprisingly, the double localisation phenomenon seem to be independent of [...]
Holocene tephrochronology of Kerguelen Archipelago, Subantarctic Indian Ocean
Published: 2020-05-20
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Volcanology
Up to now, no geochemical or geochronological data has been published about Holocene volcanic activity on the Kerguelen Archipelago. Here we present the first continuous Holocene chronology of volcanic eruptions on the archipelago. We compared sedimentological, geochronological and geochemical data from two lake sediment cores taken in two different depocenters of Lake Armor, located ca. 70 km [...]