Preprints
Filtering by Subject: Earth Sciences
Shark-fins: overturned patterns linked to shear instabilities at the flow-bed boundary. Examples from the deposits of the 2006 pyroclastic currents at Tungurahua volcano (Ecuador)
Published: 2018-08-06
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Volcanology
Enigmatic structures grouped under the term "shark-fins" are documented in laminated deposits of pyroclastic currents. They consist of an overturning of a few laminae on a decimeter scale, forming overbent "flames" or convolute laminae, which occur in successive, periodic patterns. More than 200 shark-fins were investigated and measured in cross-laminated deposits from the 2006 pyroclastic [...]
Pyroclastic dune bedforms: macroscale structures and lateral variations. Examples from the 2006 pyroclastic currents at Tungurahua (Ecuador)
Published: 2018-08-06
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Volcanology
Pyroclastic currents are catastrophic flows of gas and particles triggered by explosive volcanic eruptions. For much of their dynamics, they behave as particulate density currents and share similarities with turbidity currents. Pyroclastic currents occasionally deposit dune bedforms with peculiar lamination patterns, from what is thought to represent the dilute low concentration and [...]
Backprojection to image slip
Published: 2018-08-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Waveform backprojection is a key technique of earthquake-source imaging, which has been widely used for extracting information of earthquake source evolution that cannot be obtained by kinematic source inversion. The technique enjoys considerable popularity, owing to the simplicity of its implementation and the robustness of its processing, but the physical meaning of backprojection images has [...]
Dynamic viability of the 2016 Mw 7.8 Kaikōura earthquake cascade on weak crustal faults
Published: 2018-07-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a dynamic rupture model of the 2016 Mw 7.8 Kaikōura earthquake to unravel the event’s riddles in a physics-based manner and provide insight on the mechanical viability of competing hypotheses proposed to explain them. Our model reproduces key characteristics of the event and constraints puzzling features inferred from high-quality observations including a large gap separating surface [...]
Lubrication of dislocation glide in forsterite by Mg vacancies: insights from Peierls-Nabarro modeling
Published: 2018-07-26
Subjects: Condensed Matter Physics, Earth Sciences, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics, Physics
Dislocation glide is an important contributor to the rheology of olivine under conditions of high stress and low to moderate temperature, such as occur in mantle wedges. Interactions between point defects and dislocation core may alter the Peierls stress,
Fluid inclusions from the deep Dead Sea sediment provide new insights on Holocene extreme microbial life
Published: 2018-07-24
Subjects: Biology, Earth Sciences, Environmental Microbiology and Microbial Ecology Life Sciences, Life Sciences, Microbiology, Paleobiology, Physical Sciences and Mathematics
The Dead Sea Deep Drilling Project allowed to retrieve a continuous sedimentary record spanning the two last glacial cycles. This unique archive, in such an extreme environment, has allowed for the development of new proxies and the refinement of already available paleoenvironmental studies. In particular, the interaction of the lake and sediment biosphere with elements and minerals that [...]
Lithologic controls on the form of soil mantled hillslopes
Published: 2018-07-20
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics
Slopes in steady-state soil-mantled landscapes tend to increase downslope in a way that balances local transport capacity with the sediment supplied from progressively larger source areas. Most formulations of sediment transport due to hillslope processes scale transport rate with local slope, which produces convex-up forms that are independent of the properties of the underlying lithologies. In [...]
SITE RESPONSE ACROSS THE LOS ANGELES BASIN FROM AMBIENT NOISE RECORDED BY A HIGH DENSITY ARRAY
Published: 2018-07-20
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Sedimentary basins, such as the Los Angeles basin, can substantially amplify ground motion and increase its duration. To account for site response and develop better seismic hazard assessment and mitigation, it is essential to determine site characteristics across the basin at a high spatial resolution. We investigate site response within the Los Angeles Basin through the application of the [...]
Using Dark Fiber and Distributed Acoustic Sensing for Near-Surface Characterization and Broadband Seismic Event Detection
Published: 2018-07-20
Subjects: Earth Sciences, Geophysics and Seismology, Hydrology, Physical Sciences and Mathematics
We present the first case study demonstrating the use of regional unlit fiber-optic telecommunication infrastructure (dark fiber) and distributed acoustic sensing for broadband seismic monitoring of both near-surface soil properties and earthquake seismology. We recorded 7 months of passive seismic data on a 27 km section of dark fiber stretching [...]
Higher potential compound flood risk in Northern Europe under anthropogenic climate change
Published: 2018-07-18
Subjects: Applied Mathematics, Atmospheric Sciences, Climate, Earth Sciences, Environmental Sciences, Hydrology, Multivariate Analysis, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Other Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Physics, Statistics and Probability
The published version of this article is available at https://advances.sciencemag.org/content/5/9/eaaw5531. Compound flooding (CF) is an extreme event taking place in low-lying coastal areas as a result of co-occurring high sea level and large amounts of runoff, caused by precipitation. The impact from the two hazards occurring individually can be significantly lower than the result of their [...]
Capturing the Mesoarchean Emergence of Continental Crust in the Coorg Block, Southern India
Published: 2018-07-17
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Tectonics and Structure
The emergence of Earths continental crust above sea‐level is debated. To assess whether emergence can be observed at a regional scale, we present zircon U‐Pb‐Hf‐O isotope data from magmatic rocks of the Coorg Block, southern India. A 3.5 Ga granodiorite records the earliest felsic crust in the region. Younger phases of magmatism at 3.37‐3.27 Ga and 3.19‐3.14 Ga, comprising both reworked crust and [...]
Historical trajectories of disaster risk in Dominica
Published: 2018-07-13
Subjects: Earth Sciences, Environmental Sciences, Natural Resources Management and Policy, Physical Sciences and Mathematics, Soil Science, Tectonics and Structure, Water Resource Management
The calamitous consequences of Hurricane Maria (2017) for the Caribbean island of Dominica highlighted the acute and increasing susceptibility of the region to hazard events. Despite the increasing international attention given to disaster risk reduction, recovery from hazard events can be especially lengthy and difficult for Small Island Developing States. In this paper we build on existing [...]
Strain Localization and Weakening Processes in Viscously Deforming Rocks: Numerical Modeling Based on Laboratory Torsion Experiments
Published: 2018-07-12
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Localization processes in the viscous lower crust lead to the formation of deformation zones over a broad range of scales that may affect the mechanical response of faults in the upper crust during the entire seismic cycle. In order to gain detailed insight into the processes involved in strain localization and rheological weakening in viscously deforming rocks we conduct centimeter-scale [...]
Tectonic and oceanographic process interactions archived in the Late Cretaceous to Present deep-marine stratigraphy on the Exmouth Plateau, offshore NW Australia
Published: 2018-07-11
Subjects: Earth Sciences, Engineering, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure
Deep-marine deposits provide a valuable archive of process interactions between sediment gravity flows, pelagic sedimentation, and thermo-haline bottom-currents. Stratigraphic successions can also record plate-scale tectonic processes (e.g. continental breakup and shortening) that impact long-term ocean circulation patterns, including changes in climate and biodiversity. One such setting is the [...]
The rupture extent of low frequency earthquakes near Parkfield, CA
Published: 2018-07-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The low frequency earthquakes (LFEs) that constitute tectonic tremor are often inferred to be slow: to have durations of 0.2 to 0.5 s, a factor of 10 to 100 longer than those of typical Mw 1-2 earthquakes. Here we examine LFEs near Parkfield, CA in order to assess several proposed explanations for LFEs long durations. We determine LFE rupture areas and location distributions using a new approach, [...]