Preprints
Filtering by Subject: Physical Sciences and Mathematics
Reducing variability in OSL rock surface dating profiles.
Published: 2021-03-17
Subjects: Physical Sciences and Mathematics
In recent years, rock surface dating has seen the emergence of a technique based on optically stimulated luminescence (OSL). This application translates the depth of OSL signal bleaching within a rock surface into an exposure age or erosion rate at 1-10000 a timescales. Considerable effort has been undertaken to improve our understanding of OSL rock surface dating, yet a large amount of [...]
Prototyping a collaborative data curation service for coastal science
Published: 2021-03-16
Subjects: Environmental Sciences, Geomorphology, Physical Sciences and Mathematics
The growing push for open data has resulted in an abundance of data for coastal researchers, which can lead to problems for individual researchers related to discoverability of relevant data. One solution is to explicitly develop services for coastal researchers to help curate data for discovery, hosting discussions around reuse, community building, and finding collaborators. To develop the idea [...]
Pre-salt rift morphology controls salt tectonics in the Campos Basin, offshore SE Brazil
Published: 2021-03-14
Subjects: Physical Sciences and Mathematics
Classic models of gravity-driven salt tectonics commonly depict kinematically-linked zones of overburden deformation, characterised by updip extension and downdip contraction, separated by a weakly deformed zone associated with downdip translation above a relatively smooth base-salt surface. We use 2D and 3D seismic reflection and borehole data from the south-central Campos Basin to show that [...]
High resolution, annual maps of field boundaries for smallholder-dominated croplands at national scales
Published: 2021-03-12
Subjects: Agriculture, Environmental Monitoring, Environmental Sciences, Geographic Information Sciences, Geography, Life Sciences, Natural Resources and Conservation, Physical and Environmental Geography, Physical Sciences and Mathematics, Remote Sensing, Spatial Science, Sustainability
Mapping the characteristics of Africa's smallholder-dominated croplands, including the sizes and numbers of fields, can provide critical insights into food security and a range of other socioeconomic and environmental concerns. However, accurately mapping these systems is difficult because there is 1) a spatial and temporal mismatch between satellite sensors and smallholder fields, and 2) a lack [...]
Magma pathways in sill-complexes
Published: 2021-03-09
Subjects: Physical Sciences and Mathematics
The Loch Scridain Sill-complex on the Isle of Mull affords an opportunity to examine how magma moves through and builds sill-complexes (Holness & Humphreys 2003). For example, field and petrological evidence indicates the Tràigh Bhàn na Sgùrra Sill is segmented and comprised several thick channels, separated by thin sill portions, that facilitated longer-lived magma flow (Holness & Humphreys [...]
Segment tip geometry of sheet intrusions, I: Theory and numerical models for the role of tip shape in controlling propagation pathways.
Published: 2021-03-09
Subjects: Physical Sciences and Mathematics
Inferences about sheet intrusion emplacement mechanisms have been built largely on field observations of intrusion tip zones: magmatic systems that did not grow beyond their observed state. Here we use finite element simulation of elliptical to superelliptical crack tips, representing observed natural sill segments, to show the effect of sill tip shape in controlling local stress concentrations, [...]
Decadal shoreline erosion and recovery of beaches in modified and natural estuaries
Published: 2021-03-08
Subjects: Geomorphology, Physical Sciences and Mathematics
Sandy beaches in estuaries and bays (BEBs) are common landforms on the coasts of many major cities. They exist under a wide range of settings and their morphology is controlled by their distance from the estuary/bay entrance, exposure to different types of waves (e.g., ocean swells vs locally generated wind waves), proximity to flood-tide delta/shoals, and anthropogenic interventions (e.g., [...]
Recrystallization of ice enhances the creep and vulnerability to fracture of ice shelves
Published: 2021-03-08
Subjects: Earth Sciences, Geophysics and Seismology, Glaciology, Physical Sciences and Mathematics
The initiation of fractures and fast flow in floating regions of Antarctica have the potential to destabilize large regions of the grounded ice sheet, leading to significant sea-level rise. While observations have shown rapid, localized deformation and damage in the margins of fast-flowing glaciers, there remain gaps in our understanding of how rapid deformation affects the viscosity and [...]
Topographic response to Neogene variations in slab geometry, climate and drainage reorganization in the Northern Andes of Colombia
Published: 2021-03-05
Subjects: Physical Sciences and Mathematics
The tropical Northern Andes of Colombia are one the world's most biodiverse places, offering an ideal location for unraveling the linkages between the geodynamic forces that build topography and the evolution of the biota that inhabit it. In this study, we utilize geomorphic analysis to characterize the topography of the Western and Central Cordilleras of the Northern Andes. We supplement our [...]
Mechanical properties of quartz sand and gypsum powder (plaster) mixtures: implications for laboratory model analogues for the Earth’s upper crust
Published: 2021-03-05
Subjects: Physical Sciences and Mathematics
Granular materials are a useful analogue for the Earth’s crust in laboratory models of deformation. Constraining their mechanical properties is critical for such model’s scaling and interpretation. Much information exists about monomineralic granular materials, such as quartz sand, but the mechanical characteristics of bimineralic mixtures, such as commonly-used quartz sand mixed with gypsum [...]
Assessing Margin-Wide Rupture Behaviors along the Cascadia Megathrust with 3-D Dynamic Rupture Simulations
Published: 2021-03-05
Subjects: Physical Sciences and Mathematics
From California to British Columbia, the Pacific Northwest coast bears an omnipresent earthquake and tsunami hazard from the Cascadia subduction zone. Multiple lines of evidence suggests that magnitude eight and greater megathrust earthquakes have occurred - the most recent being 321 years ago (i.e., 1700 A.D.). Outstanding questions for the next great megathrust event include where it will [...]
Crisis at the Salton Sea: The Vital Role of Science
Published: 2021-03-03
Subjects: Atmospheric Sciences, Biogeochemistry, Chemistry, Climate, Earth Sciences, Environmental Chemistry, Environmental Public Health, Environmental Sciences, Environmental Studies, Geochemistry, Geology, Geomorphology, Hydrology, Medicine and Health Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Public Health, Social and Behavioral Sciences
The Salton Sea—a hypersaline, terminal lake in southern California—is in crisis. A combination of mismanagement and competition among federal, state and local agencies has hindered efforts to address declining lake levels and unstable water chemistry. This delay has heightened the public health threat to regional communities as retreating shorelines expose dry lakebed— a source of potentially [...]
Use of machine learning to estimate statistics of the posterior distribution in probabilistic inverse problems - an application to airborne EM data.
Published: 2021-03-03
Subjects: Earth Sciences, Physical Sciences and Mathematics
The solution to a probabilistic inverse problem is the posterior probability distribution for which a full analytic expression is rarely possible. Sampling methods are therefore often used to generate a sample from the posterior. Decision-makers may be interested in the probability of features related to model parameters (for example existence of a pollution or the cumulative clay thickness) [...]
Estimating Ocean Surface Currents from Satellite Observable Quantities with Machine Learning
Published: 2021-03-03
Subjects: Physical Sciences and Mathematics
Global surface currents are usually inferred from directly observed quantities like sea-surface height, wind stress by applying diagnostic balance relations (like geostrophy and Ekman flow), which provide a good approximation of the dynamics of slow, large-scale currents at large scales and low Rossby numbers. However, newer generation satellite altimeters (like the upcoming SWOT mission) will [...]
Seasonal dispersal of fjord meltwaters as an important source of iron to coastal Antarctic phytoplankton
Published: 2021-03-03
Subjects: Physical Sciences and Mathematics
Glacial meltwater from the western Antarctic Ice Sheet is hypothesized to be an important source of cryospheric iron, fertilizing the Southern Ocean, yet its trace metal composition and factors which control its dispersal remain poorly constrained. Here we characterize meltwater iron sources in a heavily glaciated western Antarctic Peninsula (WAP) fjord. Using dissolved and particulate ratios of [...]