Preprints
Filtering by Subject: Physical Sciences and Mathematics
Comments on “On the reported magnetic precursor of the 1989 Loma Prieta earthquake” by J.N. Thomas, J.J. Love, and M.J.S. Johnston
Published: 2021-01-06
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Thomas et al. (2009) (hereafter TLJ09) attempt to cast doubt upon the report by FraserSmith et al. (1990) (hereafter FS90) of unusual large-amplitude ultra-low frequency (ULF; f < 10 Hz) magnetic fields preceding the M ~7 Loma Prieta earthquake. TLJ09 suggest there are instrumental problems with FS90’s data that we, the designers, builders and long-term operators of the equipment, are presumed to [...]
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 [...]
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 [...]
Bayesian Seismic Tomography using Normalizing Flows
Published: 2020-12-27
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 [...]
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 [...]
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 [...]
Tidal dynamics in palaeo-seas in response to changes in physiography, tidal forcing, and bed shear stress
Published: 2020-12-21
Subjects: Physical Sciences and Mathematics
Simulating hydrodynamic conditions in palaeo-ocean basins is needed to better understand the effects of tidal forcing on the sedimentary record. When combined with sedimentary analyses, hydrodynamic modelling can help inform complex temporal and spatial variability in the sediment distribution of tide-dominated palaeo-ocean basins. Herein, palaeotidal modelling of the epicontinental Upper [...]
Small-scale lithospheric heterogeneity characterization using Bayesian inference
Published: 2020-12-18
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Observations from different disciplines have shown that our planet is highly heterogeneous at multiple scale lengths. Still, many seismological Earth models tend not to include any small-scale heterogeneity or lateral velocity variations, which can affect measurements and predictions based on these homogeneous models. In this study, we describe the lithospheric small-scale heterogeneity structure [...]
Given that the Paris Agreement is unlikely to prevent dangerous climate overshoot, an alternative risk management strategy is urgently needed
Published: 2020-12-18
Subjects: Life Sciences, Physical Sciences and Mathematics, Social and Behavioral Sciences
Because the 2015 Paris Agreement will not prevent dangerous climate change, there is an urgent need to develop an alternative mitigation strategy. Even if most countries greatly increase their commitments and technological breakthroughs accelerate the transition to emission-free technologies, the 2°C target will still be overshot due to systemic inertia from existing greenhouse gases, warming [...]
Constraining the 410-km Discontinuity and Slab Structure in the Kuril Subduction Zone with Triplication Waveforms
Published: 2020-12-17
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The detailed structure near the 410-km discontinuity provides key constraints of the dynamic interactions between the upper mantle and the lower mantle through the mantle transition zone (MTZ) via mass and heat exchange. Meanwhile, the temperature of the subducting slab, which can be derived from its fast wave speed perturbation, is critical for understanding the mantle dynamics in subduction [...]
Future changes in Northern Hemisphere summer weather persistence linked to projected Arctic warming.
Published: 2020-12-17
Subjects: Physical Sciences and Mathematics
Understanding the response of the large-scale atmospheric circulation to climatic change remains a key challenge. Specifically, changes in the equator-to-pole temperature difference have been suggested to affect the mid-latitudes, potentially leading to more persistent extreme weather, but a scientific consensus has not been established so far. Here we quantify summer weather persistence by [...]