Preprints
Filtering by Subject: Earth Sciences
On the scales of dynamic topography in whole-mantle convection models - preprint version
Published: 2017-10-29
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Mantle convection shapes Earths surface by generating dynamic topography. Observational constraints and regional convection models suggest that surface topography could be sensitive to mantle flow for wavelengths as short as 1,000 km and 250 km, respectively. At these spatial scales, surface processes including sedimentation and relative sea-level change occur on million year timescales. [...]
A Bayesian Method to Quantify Azimuthal Anisotropy Model Uncertainties: Application to Global Azimuthal Anisotropy in the Upper Mantle and Transition Zone
Published: 2017-10-28
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Seismic anisotropy is a powerful tool to constrain mantle deformation, but its existence in the deep upper mantle and topmost lower mantle is still uncertain. Recent results from higher mode Rayleigh waves have, however, revealed the presence of 1% azimuthal anisotropy between 300 km and 800 km depth, and changes in azimuthal anisotropy across the mantle transition zone boundaries. This has [...]
Igneous sills record far-field and near-field stress interactions during volcano construction: Isle of Mull, Scotland
Published: 2017-10-28
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Sill emplacement is typically associated with horizontally mechanically layered host rocks in a near-hydrostatic far-field stress state, where contrasting mechanical properties across the layers promote transitions from dykes, or inclined sheets, to sills. We used detailed field observations from the Loch Scridain Sill Complex (Isle of Mull, UK), and mechanical models to show that layering is not [...]
Influence of fault reactivation during multiphase rifting: the Oseberg area, Northern North Sea rift
Published: 2017-10-28
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Multiphase rifts tend to produce fault populations that evolve by the formation of new faults and reactivation of earlier faults. The resulting fault patterns tend to be complex and difficult to decipher. In this work we use seismic reflection data to examine the evolution of a normal fault network in the Oseberg Fault Block in the northern North Sea Rift System – a rift system that experienced [...]
Pre-existing normal faults have limited control on the rift geometry of the northern North Sea
Published: 2017-10-28
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Many rifts develop in response to multiphase extension with numerical and physical models suggesting that reactivation of first-phase normal faults and rift-related variations in bulk crustal rheology control the evolution and final geometry of subsequent rifts. However, many natural multiphase rifts are deeply buried and thus poorly exposed in the field and poorly imaged in seismic reflection [...]
Balancing sub- and supra-salt strain in salt-influenced rifts: Implications for extension estimates
Published: 2017-10-28
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
The structural style of salt-influenced rifts may differ from those formed in predominantly brittle crust. Salt can decouple sub- and supra-salt strain, causing sub-salt faults to be geometrically decoupled from, but kinematically coupled to and responsible for, supra-salt forced folding. Salt-influenced rifts thus contain more folds than their brittle counterparts, an observation often ignored [...]
The role of microbes in snowmelt and radiative forcing on an Alaskan icefield
Published: 2017-10-26
Subjects: Biogeochemistry, Earth Sciences, Glaciology, Physical Sciences and Mathematics
A lack of liquid water limits life on glaciers worldwide but specialized microbes still colonize these environments. These microbes reduce surface albedo, which, in turn, could lead to warming and enhanced glacier melt. Here we present results from a replicated, controlled field experiment to quantify the impact of microbes on snowmelt in red-snow communities. Addition of [...]
Preprint: Tremor migration patterns and the collective behavior of deep asperities mediated by creep
Published: 2017-10-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Slow-slip events (SSE) and non-volcanic tremors have revealed a broad spectrum of earthquake behavior, involving entangled seismic and aseismic slip, and offer a unique window into fault mechanics at the bottom of seismogenic zones. A hierarchy of migration patterns of tremors has been observed in the Cascadia subduction zone, including large-scale along-strike tremor propagation and Rapid Tremor [...]
Continuous separation of land use and climate effects on the past and future water balance
Published: 2017-10-26
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics
Understanding the combined and separate effects of climate and land use change on the water cycle is necessary to mitigate negative impacts. However, existing methodologies typically divide data into discrete (before and after) periods, implicitly representing climate and land use as step changes when in reality these changes are often gradual. Here, we introduce a new regression-based [...]
Preconditioning and triggering of offshore slope failures and turbidity currents revealed by most detailed monitoring yet at a fjord-head delta
Published: 2017-10-26
Subjects: Earth Sciences, Geology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Sedimentology
Rivers and turbidity currents are the two most important sediment transport processes by volume on Earth. Various hypotheses have been proposed for triggering of turbidity currents offshore from river mouths, including direct plunging of river discharge, delta mouth bar flushing or slope failure caused by low tides and gas expansion, earthquakes and rapid sedimentation. During 2011, 106 turbidity [...]
Thermo-mechanical numerical model of the transition from continental rifting to oceanic spreading: the case study of the Alpine Tethys
Published: 2017-10-26
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
We develop a two-dimensional thermo-mechanical numerical model in which the formation of oceanic crust and serpentinite due to the hydration of the uprising mantle peridotite has been implemented, with the aim of discussing the behavior of the lithosphere of the Alps and Northern Apennines during the transition from continental rifting to ocean spreading of the Alpine Tethys. The predictions of [...]
Morphological expressions of crater infill collapse: model simulations of Chaotic Terrains on Mars
Published: 2017-10-26
Subjects: Earth Sciences, Geology, Geomorphology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Martian chaotic terrains are characterized by deeply depressed intensively fractured areas that contain a large number of low-strain tilted blocks. Stronger deformation (e.g. higher number of fractures) is generally observed in the rims when compared to the middle regions of the terrains. The distribution and number of fractures and tilted blocks are correlated with the size of the chaotic [...]
2-D numerical study of hydrated wedge dynamics from subduction to post-collisional phases
Published: 2017-10-26
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
We developed a 2-D finite element model to investigate the effect of shear heating and mantle hydration on the dynamics of the mantle wedge area. The model considers an initial phase of active oceanic subduction, which is followed by a post-collisional phase characterized by pure gravitational evolution. To investigate the impact of the subduction velocity on the thermomechanics of the system, [...]
Direct monitoring of active geohazards: emerging geophysical tools for deep-water assessments
Published: 2017-10-26
Subjects: Earth Sciences, Geology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Sedimentology
Seafloor networks of cables, pipelines, and other infrastructure underpin our daily lives, providing communication links, information, and energy supplies. Despite their global importance, these networks are vulnerable to damage by a number of natural seafloor hazards, including landslides, turbidity currents, fluid flow, and scour. Conventional geophysical techniques, such as high-resolution [...]
Distal turbidites reveal a common distribution for large (>0.1 km3) submarine landslide recurrence
Published: 2017-10-26
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Probability, Sedimentology, Statistics and Probability
Submarine landslides can be far larger than those on land, and are one of the most important processes for moving sediment across our planet. Landslides that are fast enough to disintegrate can generate potentially very hazardous tsunamis, and produce long run-out turbidity currents that break strategically important cable networks. It is important to understand their frequency and triggers. We [...]