Preprints
Filtering by Subject: Physical Sciences and Mathematics
Bridging Spatiotemporal Scales of Normal Fault Growth During Continental Extension Using High-Resolution 3D Numerical Models
Published: 2021-04-21
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Continental extension is accommodated by the development of kilometre-scale normal faults, which grow during metre-scale slip events that occur over millions of years. However, reconstructing the entire lifespan of a fault remains challenging due to a lack of observational data with spatiotemporal scales that span the early stage (<10^6 yrs) of fault growth. Using 3D numerical simulations of [...]
Decadal Evaluation of the AIRPACT Regional Air Quality Forecast System in the Pacific Northwest from 2009-2018
Published: 2021-04-21
Subjects: Engineering, Physical Sciences and Mathematics
The Air Indicator Report for Public Awareness and Community Tracking (AIRPACT) is a comprehensive, automated air quality forecast system that provides 48-hr in-advance air quality over the Pacific Northwest region (http://lar.wsu.edu/airpact/). Since 2001, the AIRPACT forecasting system has been successfully operated by Washington State University, with the financial support from the Northwest [...]
Poleward shift in the Southern Hemisphere westerly winds synchronous with the deglacial rise in CO2
Published: 2021-04-21
Subjects: Physical Sciences and Mathematics
The Southern Hemisphere westerly winds influence deep ocean circulation and carbon storage. While the westerlies are hypothesised to play a key role in regulating atmospheric CO2 over glacial-interglacial cycles, past changes in their position and strength remain poorly constrained. Here, we use a compilation of planktic foraminiferal delta-18O from across the Southern Ocean and emergent [...]
The stabilizing effect of high pore-fluid pressure along subduction megathrust faults: Evidence from friction experiments on accretionary sediments from the Nankai Trough
Published: 2021-04-21
Subjects: Physical Sciences and Mathematics
Pore-fluid pressure is an important parameter in controlling fault mechanics as it lowers the effective normal stress, allowing fault slip at lower shear stress. It is also thought to influence the nature of fault slip, particularly in subduction zones where areas of slow slip have been linked to regions of elevated pore-fluid pressure. Despite the importance of pore-fluid pressure on fault [...]
A deep-learning estimate of the decadal trends in the Southern Ocean carbon storage
Published: 2021-04-20
Subjects: Atmospheric Sciences, Biogeochemistry, Climate, Earth Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Uptake of atmospheric carbon by the ocean, especially at high latitudes, plays an important role in offsetting anthropogenic emissions. At the surface of the Southern Ocean south of 30◦S, the ocean carbon uptake, which had been weakening in 1990s, strengthened in the 2000s. However, sparseness of in-situ measurements in the interior make it difficult to compute changes in carbon storage below [...]
Water acceleration in a supraglacial channel predicts locations of step-pool sequence formation
Published: 2021-04-20
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Supraglacial channels constitute an important part of the glacial hydrological system, both by influencing surface energy exchange as well as routing meltwater to eventually feed en- and subglacial drainage systems. Subglacial systems have received considerable scientific interest, but specific studies of supraglacial channels are sparse. This limited scientific understanding represents a missing [...]
The Mid-Lithospheric Discontinuity caused by channel flow in the cratonic lithosphere
Published: 2021-04-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Stable cratons with a thick (> 200 km) and cold lithosphere form rheologically strong plates that move atop a ductile asthenospheric mantle. Various types of seismic observations show the presence of a potentially rheologically weak zone at depths of ca. 80 – 150 km termed the Mid-Lithosphere Discontinuity (MLD). While various mechanisms may explain the MLD, the dynamic processes leading to the [...]
Revision of thelodonts, acanthodians, conodonts, and the depositional environments in the Burgen outlier (Ludlow, Silurian) of Gotland, Sweden
Published: 2021-04-20
Subjects: Biodiversity, Earth Sciences, Ecology and Evolutionary Biology, Life Sciences, Physical Sciences and Mathematics
Ludfordian strata exposed in the Burgen outlier in eastern Gotland record a time of initial faunal recovery after a global environmental perturbation manifested in the Ludfordian Carbon Isotope Excursion (LCIE). Vertebrate microfossils in the collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, hold the key to reconstruct the dynamics of faunal immigration and [...]
The Effect of Ti on Ca-pv and Mg-pv phase stability
Published: 2021-04-20
Subjects: Physical Sciences and Mathematics
Magnesium silicate perovskite in the form of bridgmanite (bdg) and Calcium silicate perovskite (Ca-pv) have similar chemical structures and may mix into a single perovskite phase in the lower mantle which would have profound effects on many seismic properties. While we have previously found that this is unlikely to occur in pure bdg and ca-pv in this paper we examine whether phase mixing can be [...]
Particulate PhozzyLogic Index for policy makers—an index for a more accurate and transparent identification of critical source areas
Published: 2021-04-20
Subjects: Environmental Sciences, Physical Sciences and Mathematics, Water Resource Management
This study presents an algorithm for the allocation of particulate phosphorus (PP) loads entering surface waters to their sources of origin, which is a basic requirement for the identification of critical PP source areas and in turn a cost-effective implementation of mitigation measures. Furthermore, it conducts a sensitivity analysis determining the impacts of storm drains, discharge frequencies [...]
Reactivation Potential of Intraplate Faults in the Western Quebec Seismic Zone, Eastern Canada
Published: 2021-04-19
Subjects: Earth Sciences, Physical Sciences and Mathematics
The intraplate western Quebec seismic Zone (WQSZ) in eastern Canada experiences moderate seismicity that mainly results from reactivation of inherited structures under the present-day, NE-striking regional stress field and, possibly to a minor extent, through stress perturbations in response to glacio-isostatic adjustments. This work comprises the first numerical stress simulation-based study [...]
Comparison of Machine Learning Approaches for Tsunami Forecasting from Sparse Observations
Published: 2021-04-18
Subjects: Physical Sciences and Mathematics
We have explored various different machine learning (ML) approaches for forecasting tsunami amplitudes at a set of forecast points, based on hypothetical short-time observations at one or more observation points. As a case study, we chose an observation point near the entrance of the Strait of Juan de Fuca, and two forecast points in the Salish Sea, one in Discovery Bay and the other in Admiralty [...]
The effect of water and pressure on fabric development in olivine
Published: 2021-04-17
Subjects: Physical Sciences and Mathematics
Water has a very strong effect on both the strength and fabric development of forsterite but the mechanism of this effect is unclear. In the paper we use Density Functional Theory Peierls-Nabarro modelling to examine the effect of water on the Peierls stress of different forsterite slip systems. We find that water in Mg vacancies will weaken [100](010) slip and thus produce A fabrics while [...]
Controls on the distribution of hydrous defects in forsterite from a thermodynamic model
Published: 2021-04-15
Subjects: Physical Sciences and Mathematics
The distribution of hydrogen across different crystallographic sites and point defects in forsterite is important because it determines how many properties, such as rheology, conductivity, diffusion and elemental partitioning are affected by water. In this study we use lattice dynamics and Density Functional Theory (DFT) to build a thermodynamic model of H-bearing defects that incorporates both [...]
Source region geochemistry from unmixing downstream sedimentary elemental compositions
Published: 2021-04-15
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The geochemistry of river sediments is routinely used to obtain information about geologic and environmental processes occurring upstream. For example, downstream samples are used to constrain chemical weathering and physical erosion rates upstream, as well as the locations of mineral deposits or contaminant sources. Previous work has shown that, by assuming conservative mixing, the geochemistry [...]