Preprints
Filtering by Subject: Earth Sciences
On the Evolution of Thermally Stratified Layers at the top of Earth’s Core
Published: 2020-08-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Stable stratification at the top of the Earth’s outer core has been suggested based upon seismic and geomagnetic observations, however, the origin of the layer is still unknown. In this paper we focus on a thermal origin for the layer and conduct a systematic study on the thermal evolution of the core. We develop a new numerical code to model the growth of thermally stable layers beneath the CMB, [...]
Fernandes and Roberts (2020) - preprint
Published: 2020-08-16
Subjects: Earth Sciences, Environmental Sciences, Geology, Geomorphology, Paleobiology, Physical Sciences and Mathematics, Planetary Sciences, Tectonics and Structure
There are many geoscience problems for which constraining histories of uplift or subsidence of Earth’s surface is of direct or indirect importance, for example reconstructing tectonics, mantle convection, geomorphology, sedimentary and chemical flux, biodiversity, glacio-eustasy and climate change. The least equivocal constraints on timing and amplitude of vertical motions on geological [...]
Rapid finite-frequency microseismic noise source inversion at regional to global scales
Published: 2020-08-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Ambient noise cross-correlations can be used as self-consistent observables, opening novel possibilities for investigating ambient noise sources. To optimise the forward- modelling of global ambient cross-correlations for any given noise distribution of noise sources in the microseismic frequency range up to 0.2 Hz, we implement (i) pre-computed wavefields and (ii) spatially variable grids. This [...]
A Comprehensive Flood Event Specification and Inventory: 1930-2020 Turkey Case Study
Published: 2020-08-16
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Sciences, Physical Sciences and Mathematics, Water Resource Management
Flooding is one of the most frequent natural disasters that have significant impact on communities in terms of loss of life, direct and indirect economic losses, and disruption of daily life. Decision makers often consult flood data inventories to make more informed decisions on the development of flood mitigation plans to protect flood prone communities. A comprehensive inventory that covers [...]
Bedload transport in rivers: size matters but so does shape!
Published: 2020-08-16
Subjects: Earth Sciences, Geomorphology, Hydrology, Physical Sciences and Mathematics, Sedimentology
Bedload transport modelling in rivers, which defines the threshold for pebble movement, takes into account the size and density of pebbles, but does not formally consider particle shape. The lack of analyses evaluating the influences of shape and density on particle mobility presents a major deficiency. To address this issue and to compare the relative roles of the density and shape of particles, [...]
Bridging the gap between geophysics and geology with Generative Adversarial Networks (GANs)
Published: 2020-08-16
Subjects: Artificial Intelligence and Robotics, Computer Sciences, Databases and Information Systems, Earth Sciences, Environmental Monitoring, Environmental Sciences, Geology, Geomorphology, Geophysics and Seismology, Natural Resource Economics, Oil, Gas, and Energy, Other Earth Sciences, Physical Sciences and Mathematics, Sedimentology, Water Resource Management
Inverse mapping from geophysics to geology is a difficult problem due to the inherent uncertainty of geophysical data and the spatially heterogeneous patterns (structure) in geology. We describe GANSim, a type of generative adversarial networks (GANs) that discovers the mapping between remotely-sensed geophysical information and geology with realistic patterns, with a specially designed loss [...]
Stress, rigidity and sediment strength control megathrust earthquake and tsunami dynamics
Published: 2020-08-16
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Megathrust faults host the largest earthquakes on Earth which can trigger cascading hazards such as devastating tsunamis. Determining characteristics that control subduction zone earthquake and tsunami dynamics is critical to mitigate megathrust hazards, but is impeded by structural complexity, large spatio-temporal scales, and scarce or asymmetric instrumental coverage. Here we use [...]
A Source Clustering Approach for Efficient Inundation Modeling and Regional Scale PTHA
Published: 2020-08-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
For coastal regions on the margin of a subduction zone, near-field megathrust earthquakes are the source of the most extreme tsunami hazards, and are important to handle properly as one aspect of any Probabilistic Tsunami Hazard Assessment (PTHA). Typically, great variability in inundation depth at any point is possible due to the extreme variation in extent and pattern of slip over the fault [...]
Variability of headwater stream network extents controlled by flow regime and network hydraulic scaling
Published: 2020-08-14
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Stream networks expand and contract through time, impacting chemical export, aquatic ecosystem habitat, and water quality. Although recent advances improve prediction of the extent of the wetted channel network (L) based on discharge at the catchment outlet (Q), controls on the temporal variability of L remain poorly understood and unquantified. Here we develop a quantitative, conceptual [...]
Isotropic and Azimuthally Anisotropic Rayleigh Wave Dispersion Across the Juan de Fuca and Gorda Plates and U.S. Cascadia from Earthquake Data and Ambient Noise Two- and Three-Station Interferometry
Published: 2020-08-08
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Physics
We use data from the Cascadia Initiative (CI) amphibious array and the USArray Transportable Array to construct and compare Rayleigh wave isotropic and azimuthally anisotropic phase speed maps across the Juan de Fuca and Gorda Plates extending onto the continental north- western United States. Results from both earthquakes (28–80 s) as well as ambient noise two- and three-station interferometry [...]
Taking the pulse of salt-detached gravity gliding in the eastern Mediterranean
Published: 2020-08-05
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
We investigate early-stage salt-detached gliding using a 3D seismic dataset from the Levant Margin in the Eastern Mediterranean, where gravitational instability due to margin uplift has caused north-westward translation of the Messinian salt sheet and its Plio-Pleistocene clastic overburden. Large, NE-trending, base-salt anticlines have allowed the basinward translation to be recorded by the [...]
Hydrogeologic and Geochemical Distinctions in Salar Freshwater Brine Systems
Published: 2020-08-05
Subjects: Earth Sciences, Geochemistry, Hydrology, Physical Sciences and Mathematics
The Salar de Atacama contains one of the world’s most important lithium resources and hosts unique and fragile desert ecosystems. Water use issues of the hyper-arid region have placed it at the center of global attention. This investigation is the first robust assessment of a salar system to incorporate geology, hydrogeology, and geochemistry of the aquifer system in the inflow, transition zone [...]
Leaky salt: pipe trails record the history of cross-evaporite fluid escape in the northern Levant Basin, Eastern Mediterranean
Published: 2020-08-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Despite salt being regarded as an extremely efficient, low-permeability hydraulic seal, an increasing number of cross-evaporite fluid escape features have been documented in salt-bearing sedimentary basins. Because of this, it is clear that our understanding of how thick salt deposits impact fluid flow in sedimentary basins is incomplete. We here examine the causes and evolution of [...]
Principal component analysis of seismic facies
Published: 2020-08-05
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic facies analyses are fundamental to the study of sedimentary, tectonic and magmatic systems using seismic reflection data. These analyses generally assume that seismic facies are: (1) well defined, (2) distinct and (3) prevalent patterns in the data. Here, we examine these assumptions critically. First, we demonstrate how to extract the main seismic facies from conventional industry [...]
Paucity of legacy oil and gas subsurface data onshore United Kingdom: implications for the expansion of low carbon subsurface activities and technologies
Published: 2020-08-04
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
The decarbonisation of energy systems to achieve net zero carbon emissions will likely see the rapid development of carbon capture and storage, energy storage in the subsurface and geothermal energy projects. Subsurface data such as seismic reflection surveys and borehole data are vital for geoscientists and engineers to carry out comprehensive assessments of both the opportunities and risks for [...]