Preprints
Filtering by Subject: Earth Sciences
Wet rice cultivation was the primary cause of the earthquake-triggered Palu landslides
Published: 2019-01-03
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics
The death toll and economic impact of an earthquake are greatly exacerbated when landslides are triggered by strong ground motion. These slides typically occur in two different contexts: localized failure of steep slopes that pose a major threat to life in areas below; and lateral spreading of nearly flat sediment plains due to shaking-induced liquefaction, which can damage large areas of [...]
Long-term and inter-annual mass changes in the Iceland ice cap determined from GRACE gravity
Published: 2019-01-03
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
The Gravity Recovery and Climate Experiment (GRACE) satellites have measured anomalies in the Earth’s time-variable gravity field since 2002, allowing for the measurement of the melting of glaciers due to climate change. Many techniques used with GRACE data have difficulty constraining mass change in small regions such as Iceland, often requiring broad averaging functions in order to capture [...]
A New Method for Simultaneously Determining The Magnitude And Orientation of SHmax And Rock Strength Using Wellbore Failures in Deviated Wells
Published: 2019-01-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Forward constraining of the magnitude of SHmax on a stress polygon using wellbore failures observed from deviated wells requires the orientation of SHmax known a priori. This orientation can be separately determined from, e.g., wellbore failures in vertical/near-vertical wells. Unfortunately, in the case where image logs are available only in highly deviated wells, SHmax orientation cannot be [...]
A test case for application of convolutional neural networks to spatio-temporal climate data: Re-identifying clustered weather patterns
Published: 2019-01-01
Subjects: Applied Mathematics, Computer Sciences, Earth Sciences, Engineering, Environmental Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Planetary Sciences
Convolutional neural networks (CNNs) can potentially provide powerful tools for classifying and identifying patterns in climate and environmental data. However, because of the inherent complexities of such data, which are often spatio-temporal, chaotic, and non-stationary, the CNN algorithms must be designed/evaluated for each specific dataset and application. Yet to start, CNN, a supervised [...]
Methane bursts as a trigger for intermittent lake-forming climates on post-Noachian Mars
Published: 2019-01-01
Subjects: Astrophysics and Astronomy, Earth Sciences, Geology, Physical Sciences and Mathematics, The Sun and the Solar System
Lakes existed on Mars later than 3.6 billion years ago, according to sedimentary evidence for deltaic deposition. The observed fluvio-lacustrine deposits suggest that individual lake-forming climates persisted for at least several thousand years (assuming dilute flow). But the lake watersheds’ little weathered soils indicate a largely dry climate history, with intermittent runoff events. Here we [...]
Persistent or repeated surface habitability on Mars during the Late Hesperian - Amazonian
Published: 2019-01-01
Subjects: Astrophysics and Astronomy, Earth Sciences, Geology, Physical Sciences and Mathematics, The Sun and the Solar System
Large alluvial fan deposits on Mars record relatively recent habitable surface conditions (≲3.5 Ga, Late Hesperian – Amazonian). We find net sedimentation rate <(4-8) μm/yr in the alluvial-fan deposits, using the frequency of craters that are interbedded with alluvial fan deposits as a fluvial-process chronometer. Considering only the observed interbedded craters sets a lower bound of >20 [...]
Seismicity induced by hydraulic fracturing and wastewater disposal in the Appalachian Basin, USA - a review
Published: 2019-01-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Eastern Ohio is an area of North America where a significant increase in seismicity rate was noted in the early 2010s. This increase has been associated with intensification of unconventional gas extraction performed in the Appalachian Basin and has been directly linked to two processes: hydraulic fracturing and disposal of the associated wastewater. In this paper we review the recent seismicity [...]
Differential Depletion-Induced 3D Stress Modification in Fault-Bounded Reservoirs and Implications for Fault Stability in Three Faulting Regimes
Published: 2019-01-01
Subjects: Earth Sciences, Environmental Sciences, Oil, Gas, and Energy, Physical Sciences and Mathematics
Depletion-induced faulting has been documented in a number of hydrocarbon reservoirs. This type of faulting has mostly been attributed to poroelastic effects: in-situ horizontal stresses are coupled with a pore pressure change according to a certain coupling coefficient (known as the stress path), which is generally less than 1. For faults with certain orientations, if the stress path is [...]
Hydromechanical–Stochastic Modeling of Fluid-Induced Seismicity in Fractured Poroelastic Media
Published: 2019-01-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present a new method for modeling fluid-perturbation induced seismicity in a fluid-saturated poroelastic medium embedded with a dual network of fractures. The inter-seismic triggering is deterministically modeled using a quasi-static, nonlinear and fluid-solid fully coupled fracture-poro-mechanical approach that resolves only the large-scale fractures. The co-seismic dynamic rupture is not [...]
The Impact of Pre-salt Rift Topography on Salt Tectonics: a Discrete-Element Modelling Approach
Published: 2018-12-30
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Gravity-driven salt tectonics along passive margins is commonly depicted as domains of updip extension and downdip contraction linked by an intermediate, broadly undeformed zone of translation. This study expands on recently published physical models by applying discrete-element modelling to demonstrate how salt-related translation over pre-salt rift structures produce complex deformation and [...]
Base-Salt Relief Controls on Salt-Tectonic Structural Style, São Paulo Plateau, Santos Basin, Brazil
Published: 2018-12-30
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Base-salt relief influences salt flow, producing three-dimensionally complex strains and multiphase deformation within the salt and its overburden. Understanding how base-salt relief influences salt-related deformation is important to correctly interpret salt basin kinematics and distribution of structural domains, which have important implications to understand the development of key petroleum [...]
Exceptional retreat of Kangerlussuaq Glacier, east Greenland, between 2016 and 2018
Published: 2018-12-28
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Kangerlussuaq Glacier is one of Greenland’s largest tidewater outlet glaciers, accounting for approximately 5% of all ice discharge from the Greenland ice sheet. In 2018 the Kangerlussuaq ice front reached its most retreated position since observations began in 1932. We determine the relationship between retreat and: (i) ice velocity; and (ii) surface elevation change, to assess the impact of the [...]
Ice shelf stability and the brittle–ductile transition
Published: 2018-12-22
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Fracturing processes limit the ability of floating ice shelves to stabilize marine ice sheets. Here, I argue that ice shelves are most susceptible to fracture when their thickness is less than the brittle–ductile transition thickness H*?, defined as the depth at which the overburden pressure equals the local yield strength in tension. A fracture mechanical analysis, compared with time-lapse [...]
Comparing the Euro 2k reconstruction to a regional climate model simulation
Published: 2018-12-20
Subjects: Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Physical Sciences and Mathematics
We do not expect simulations and reconstructions of past climate change to agree on the exact evolution of past climate variations. Simulations with sophisticated climate models present spatially discrete but complete estimates, which are consistent relative to the implemented physics and their uncertain forcing data. Reconstruction methods statistically infer past changes from natural archives [...]
Cyclic preservation of Fe/Mn-redox fronts in sediments of an oligotrophic, ventilated deep-water lake (Lago Fagnano, Tierra del Fuego)
Published: 2018-12-20
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
Changing redox conditions in lakes are captured in their sediments, and are often influenced by climate. Their study therefore allows tracing past climate change on (sub-) annual to longer time-scales. In Lago Fagnano (54°S Argentina/Chile), an oligotrophic and deep-ventilated soft-water lake, cyclic alternations of light grey clay and dark green to black laminae are preserved throughout the [...]