Preprints
There are 5531 Preprints listed.
Joint event location and 3D Poisson’s ratio tomography for downhole microseismic monitoring
Published: 2021-01-02
Subjects: Geophysics and Seismology, Physical Sciences and Mathematics
Passive seismic tomography plays a significant role in monitoring subsurface structures and properties during hydraulic fracturing. In this study, we develop a new passive seismic tomography approach to jointly invert for event locations, 3D P-wave velocity (Vp), and Poisson’s ratio models, for downhole microseimic monitoring The method enables to directly obtain the 3D Poisson’s ratio or Vp/Vs [...]
Global rates of soil production independent of soil depth
Published: 2021-01-02
Subjects: Physical Sciences and Mathematics
Accelerated rates of soil erosion threaten the stability of ecosystems1, nutrient cycles2, and global food supplies3 if the processes that produce soil cannot keep pace. Over millennial timescales, the rate of soil production is thought to keep pace with the rate of surface erosion through negative feedbacks between soil thickness and the rate at which soil is produced from the underlying mineral [...]
Identifying shale sweet spots by 3D microseismic imaging
Published: 2021-01-02
Subjects: Geophysics and Seismology, Physical Sciences and Mathematics
Several studies suggest that shale sweet spots are likely associated with low Poisson’s ratio in the shale layer. Compared with conventional geophysical techniques with active seismic data, it is straightforward and cost effective to delineate the distribution of 3D Poisson’s ratio using microseismic data. In this study, we develop a method for determining microseismic event locations, 3D P-wave [...]
Vertical slowness constrained joint anisotropic parameters and event locations inversion for downhole microseismic monitoring
Published: 2020-12-31
Subjects: Physical Sciences and Mathematics
The construction of accurate anisotropic velocity models plays a very important role in microseismic monitoring of hydraulic fracturing. Due to ignorance of anisotropy, severe distortions may happen in the results of microseismic location and interpretation. While the methods are existing that invert for anisotropic parameters and event locations simultaneously with microseismic traveltime, the [...]
Automatic microseismic stacking location with a multi-cross-correlation imaging condition
Published: 2020-12-31
Subjects: Physical Sciences and Mathematics
Source scanning algorithm (SSA) has been recognized as a valid technique to automatically detect and locate passive seismic events. The imaging condition of this algorithm is the linear stack of the amplitudes along the traveltime curve from trial locations. However, the linear stacking condition may cause the location uncertainty due to the polarity reversal and low signal-to-noise ratio of the [...]
A study of nowcast of Indian Monsoon Rainfall over Mumbai using Rainymotion
Published: 2020-12-31
Subjects: Atmospheric Sciences, Meteorology, Numerical Analysis and Scientific Computing
Since ages, we know that rainfall is a very important factor in deciding the fate of a country. In an agrarian country like India where more than 70% of rural households are dependent on agriculture, agriculture contributes to nearly 17% GDP of the country and is directly dependent on rainfall. Excessive rainfall can lead to floods, landslides, soil erosion and no rainfall can lead to [...]
Samples, Symmetries and Extensions: Exploring Parameter Space in Nonlinear Problems
Published: 2020-12-31
Subjects: Physical Sciences and Mathematics
Many scientific and technological advances require the values of a set of parameters to be constrained or estimated using recorded data. It is often possible to model data that would be recorded for particular parameter values using a computable and in general nonlinear function, where its inverse is unknown and does not exist as a unique-valued mapping. The space of parameter values must then be [...]
NIRvP: a robust structural proxy for sun-induced chlorophyll fluorescence and photosynthesis across scales
Published: 2020-12-31
Subjects: Agriculture, Biology, Environmental Monitoring, Environmental Sciences, Plant Sciences
Sun-induced chlorophyll fluorescence (SIF) is a promising new tool for remotely estimating photosynthesis. However, the degree to which incoming sunlight and the structure of the canopy rather than leaf physiology contribute to SIF variations is still not well characterized. Here we demonstrate that the canopy structure-related near-infrared reflectance of vegetation multiplied by incoming [...]
Bayesian Seismic Tomography using Normalizing Flows
Published: 2020-12-28
Subjects: Geophysics and Seismology, Physical Sciences and Mathematics
We test a fully non-linear method to solve seismic tomographic problems using data consisting of observed travel times of first-arriving waves. We use variational inference to calculate the posterior probability distribution which describes the solution to the Bayesian tomographic inverse problem. The variational method is an efficient alternate to Monte Carlo methods, which seeks the best [...]
Half a century of glacier mass balance at Cordilleras Blanca and Huaytapallana, Peruvian Andes
Published: 2020-12-23
Subjects: Glaciology
The glaciers of the tropical Andes have been observed to be losing mass for much of the last century. These changes are both driven by, and an indicator of global climate change. These glaciers are important as they represent a crucial water source for downstream communities, supplying agriculture, urban usage, industry, mining and hydropower. This study aims to quantify glacial mass loss for the [...]
Climate as a Stratigraphic Tool for Basin Margin Deposition in Intracontinental Basins
Published: 2020-12-23
Subjects: Physical Sciences and Mathematics
In intracontinental basins stratigraphic packages are not as predictable as those deposited in marine settings, namely due to a lack over an overriding control on deposition. Deposition in intracontinental basins is controlled by tectonics, climatic variations, and sediment supply. Complexity is added as deposition is affected by both autocyclic localised variations (e.g., lobe switching) and [...]
Combination of GNSS orbits using variance component estimation
Published: 2020-12-22
Subjects: Earth Sciences, Other Earth Sciences
Over the past years, the International GNSS Service (IGS) has been putting efforts into extending its service towards the Multi-GNSS Experiment and Pilot Project (MGEX). Several MGEX Analysis Centers (ACs) contribute by providing solutions containing not only GPS and GLONASS but also Galileo, BeiDou, and QZSS. The MGEX orbit and clock combination is a product that is still not consolidated inside [...]
Tectono-stratigraphic development of a salt-influenced rift margin: Halten Terrace, offshore Mid-Norway
Published: 2020-12-22
Subjects: Geology, Other Earth Sciences, Sedimentology, Tectonics and Structure
Pre-rift salt controls structural style variability within rifts by decoupling sub- and supra-salt faults. However, the way in which this variability controls sediment erosion and dispersal, and facies distributions within the coeval syn-rift stratigraphic succession, remains poorly known. We here use 3D seismic reflection and borehole data to study the tectono-stratigraphic development of the [...]
Soil erosion modelling: A global review and statistical analysis
Published: 2020-12-22
Subjects: Soil Science
To gain a better understanding of the global application of soil erosion prediction models, we comprehensively reviewed relevant peer-reviewed research literature on soil-erosion modelling 1994-2017. Our aim was to identify (i) processes and models most frequently addressed in the literature, (ii) regions within which models are primarily applied, (iii) what regions remain unaddressed and why, [...]
Yield estimation of the 2020 Beirut explosion using open access waveform and remote sensing data
Published: 2020-12-22
Subjects: Applied Statistics, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Physics, Statistics and Probability
We report on a multi-technique analysis using publicly available data for investigating the huge, accidental explosion that struck the city of Beirut, Lebanon, on August 4, 2020. Its devastating shock wave led to thousands of injured with more than two hundred fatalities and caused immense damage to buildings and infrastructure. Our combined analysis of seismological, hydroacoustic, infrasonic [...]