Preprints
Filtering by Subject: Earth Sciences
A new method for in-situ measurement of the erosion threshold of river channels
Published: 2019-06-05
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
The vast majority of alluvial deposits have some degree of cohesion, typically due to the presence of clays and/or organic matter. Determining the threshold fluid shear stress necessary to entrain these sediments is essential for predicting erosion rates and morphodynamics of rivers, tidal channels, and coasts. Cohesive sediments present a greater challenge than non-cohesive sand and gravel beds [...]
Lower crustal earthquakes in the East African Rift System: Insights from frictional properties of rock samples from the Malawi rift
Published: 2019-06-05
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Earthquakes in the southern part of the East African Rift System (EARS) occur at depths up to 45 km in the lower crust, unusually deep for an extensional regime. Typically, earthquakes in continental crust nucleate at temperatures less than 350°C, the temperature at which crystal plastic creep in quartz becomes efficient, corresponding to a depth of ~15 km with an average continental geothermal [...]
A Stratigraphic Approach to Inferring Depositional Ages From Detrital Geochronology Data
Published: 2019-06-04
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
With the increasing use of detrital geochronology data for provenance analyses, we have also developed new constraints on the age of otherwise undateable sedimentary deposits. Because a deposit can be no older than its youngest mineral constituent, the youngest defensible detrital mineral age defines the maximum depositional age of the sampled bed. Defining the youngest `defensible age in the [...]
Amplified Last-Glacial-Maximum response of Chandra valley (western Himalaya) glaciers
Published: 2019-06-03
Subjects: Earth Sciences, Geomorphology, Glaciology, Physical Sciences and Mathematics
Geomorphological evidence suggests a subdued response of Himalayan glaciers during the Last Glacial Maximum (LGM), with relatively minor advances (~10 km) reported in several glacierised valleys across the region. This supports the hypothesis that a weakened Indian summer monsoon during the LGM largely counterbalanced the effects of a colder climate on Himalayan glaciers. In contrast, a recently [...]
Characterising Land Cover Change in Brunei Darussalam’s Capital District
Published: 2019-06-03
Subjects: Computer Sciences, Earth Sciences, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Natural Resources and Conservation, Physical Sciences and Mathematics
In fast-developing regions, like Southeast-Asia, monitoring urban areas presents a challenge given the lack of publicly available data. This is an issue that precludes the nuances of a citys growth and undermines the way land-use is considered with respect to planning. The issue of data availability is very much present in the small nation of Brunei. Little is still known about the spatiotemporal [...]
Physically consistent modeling of dike induced deformation and seismicity: Application to the 2014 Bárðarbunga dike, Iceland
Published: 2019-06-03
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Dike intrusions are often associated with surface deformation and propagating swarms of earthquakes. These are understood to be manifestations of the same underlying physical process, although rarely modeled as such. We construct a physics-based model of the 2014 B\ar{\dh}arbunga dike, by far the best observed large dike ($> 0.5$ km$^3$) to date. We constrain the background stress state [...]
Glacier area and the variability of glacier change
Published: 2019-05-31
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
This is the preprint of a letter that is under review in the Journal of Glaciology. The abstract is as follows: Large-scale remote-sensing data on ice loss in the Himalaya and other glacierised regions indicate that the differences in glacier area do not significantly influence the glacier-to-glacier variability of the thinning rate. An analysis of the available data from several regions across [...]
Estimation of the total sub-debris ablation from point-scale ablation data on a debris-covered glacier
Published: 2019-05-31
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
This is the preprint of an article that is under review in the Journal of Glaciology. The abstract is as follows: Glaciological mass balance is computed from point-scale field data at a few ablation stakes that are regressed as a function of elevation, and averaged over the area-elevation distribution of the glacier. This method is contingent on a tight control of elevation on local ablation. On [...]
The glacial express
Published: 2019-05-31
Subjects: Biogeochemistry, Earth Sciences, Physical Sciences and Mathematics
Glacial calcium carbonate (CaCO3) shells are larger than interglacial CaCO3 shells. My research explores the consequences of this size difference. Because larger CaCO3 shells sink faster and dissolve more slowly than smaller CaCO3 shells, larger glacial shells underwent less dissolution than smaller interglacial shells. The resulting CaCO3 transport efficiency increase, coupled with observations [...]
The 2007 Caldera Collapse of Piton de la Fournaise Volcano: Source Process from Very-Long-Period Seismic Signals
Published: 2019-05-31
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In April 2007, Piton de la Fournaise volcano experienced its largest caldera collapse in at least 300 years. This event consisted of a series of 48 subsidence increments characterized by very-long-period (VLP) seismic signals equivalent to Mw 4.4 to 5.4. Source analysis of VLP events suggests a piston-like mechanism with a collapsing crack source corresponding to the contraction of the magma [...]
Marine biomarkers from ice cores reveal enhanced high-latitude Southern Ocean carbon sink during the Antarctic Cold Reversal
Published: 2019-05-31
Subjects: Biogeochemistry, Earth Sciences, Glaciology, Paleontology, Physical Sciences and Mathematics
Determining the feedbacks that modulate Southern Ocean carbon dynamics is key to understanding past and future climate. The global pause in rising atmospheric CO2 during the period of mid- to high-latitude southern surface cooling known as the Antarctic Cold Reversal (ACR, 14,700-12,700 years ago) provides an opportunity to disentangle competing influences. We present highly-resolved and [...]
Comments on, Scaled Random Number Simulation of High Correlation Coeffieients for Gasoline Range Compound Concentrations (unpublished results), disclosed in EarthArXiv, 5 April, 2019, by Lloyd R. Snowdon.
Published: 2019-05-30
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The paper comments on disclosure EarthArXiv 5 April, 2019 by L. R. Snowdon discounting correlations between light hydrocarbons suggesting steady-state catalysis in the origin of petroleum. The correlations are shown to be valid and Snowdons arguments not relevant.
How erosive are submarine landslides?
Published: 2019-05-30
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
Submarine landslides (slides) are ubiquitous on continental margins. They can pose a major hazard by triggering tsunami and damaging essential submarine infrastructure. Slide volume, which is a key parameter in hazard assessment, can change after initiation through substrate and/or water entrainment. However, the erosive capacity of slides is uncertain. Here, we quantify slide erosivity by [...]
A shallow earthquake swarm close to hydrocarbon activities: discriminating between natural and induced causes for the 2018–19 Surrey, UK earthquake sequence
Published: 2019-05-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquakes induced by subsurface industrial activities are a globally emotive issue, with a growing catalogue of induced earthquake sequences. However, attempts at discriminating between natural and induced causes, particularly for anomalously shallow seismicity, can be challenging. An earthquake swarm during 2018–19 in south-east England with a maximum magnitude of ML 3.2 received great public [...]
Past and projected weather pattern persistence with associated multi-hazards in the British Isles
Published: 2019-05-30
Subjects: Atmospheric Sciences, Climate, Earth Sciences, Meteorology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Hazards such as heatwaves, droughts and floods are often associated with persistent weather patterns. Atmosphere-Ocean General Circulation Models (AOGCMs) are important tools for evaluating projected changes in extreme weather. Here, we demonstrate that 2-day weather pattern persistence, derived from the Lamb Weather Types (LWTs) objective scheme, is a useful concept for both investigating [...]