Preprints
Filtering by Subject: Geophysics and Seismology
Seismic Stratigraphy of Contourite Drift Deposits Associated with the Loop Current on the Eastern Campeche Bank, Gulf of Mexico
Published: 2023-06-08
Subjects: Geophysics and Seismology, Oceanography, Sedimentology, Stratigraphy
The Loop Current is a key component of global circulation via the northward transport of warm, salty water and an important influence on Gulf of Mexico hydrography. Understanding how the Loop Current will respond to ongoing anthropogenic warming is critically important, but the history of the Loop Current is poorly known. Here, we present the results of a high resolution (3-8 m) multichannel [...]
Automated shear-wave splitting analysis for single- and multi- layer anisotropic media
Published: 2023-06-07
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Shear-wave velocity anisotropy is present throughout the earth. The strength and orientation of anisotropy can be observed by shear-wave splitting (birefringence) accumulated between earthquake sources and receivers. Seismic deployments are getting ever larger, increasing the number of earthquakes detected and the number of source-receiver pairs. Here, we present a new software package, SWSPy, [...]
A diffuse interface method for earthquake rupture dynamics based on a phase-field model
Published: 2023-06-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In traditional modeling approaches, earthquakes are often depicted as displacement discontinuities across zero-thickness surfaces embedded within a linear elastodynamic continuum. This simplification, however, overlooks the intricate nature of natural fault zones and may fail to capture key physical phenomena integral to fault processes. Here, we propose a diffuse interface description for [...]
Full vector inversion of magnetic microscopy images using Euler deconvolution as a priori information
Published: 2023-06-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Paleomagnetic data are usually obtained from whole cylindric samples, where the signal results from the sum of magnetic moments from hundreds of thousands to millions of magnetic particles within the sample volume. This usually includes both stable and unstable remanence carriers. Recently, magnetic microscopy techniques allowed the investigation of individual grains by directly imaging their [...]
Formulating and Solving the Data-Consistent Geophysical Inverse Problem for Subsurface Modeling Applications
Published: 2023-05-26
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Probability
Today, most probabilistic geophysical inverse problems are formulated using one of two methods: (1) conditional probability and Bayes’ Theorem, or (2) Tarantola’s theory of intersecting probability densities. More recently, a third inverse problem formulation based on pushforward probability measures was proposed, termed “data-consistent inversion”. Many practical problems can be cast into any of [...]
Integrated Formation Attenuation and Multiple Generator Identification from Multi-well VSP Data
Published: 2023-05-25
Subjects: Geophysics and Seismology
The Vertical Seismic Profile (VSP) is a widely used technique for extracting velocity information and seismic well tie purposes. However, the full potential of VSP data remains underutilized. This study explores the broader applicability of VSP data beyond its conventional usage by investigating its benefits for seismic data processing and interpretation. Advanced VSP products, incorporating [...]
Linking 3D long-term slow-slip cycle models with rupture dynamics: the nucleation of the 2014 Mw 7.3 Guerrero, Mexico earthquake
Published: 2023-05-25
Subjects: Geophysics and Seismology
Slow slip events (SSEs) have been observed in spatial and temporal proximity to megathrust earthquakes in various subduction zones, including the 2014 $M_\mathrm{w}$7.3 Guerrero, Mexico earthquake which was preceded by a $M_\mathrm{w}$ 7.6 SSE. However, the underlying physics connecting SSEs to earthquakes remains elusive. Here, we link 3D slow-slip cycle models with dynamic rupture simulations [...]
A Stability Analysis of Neural Networks and Its Application to Tsunami Early Warning
Published: 2023-05-14
Subjects: Geophysics and Seismology, Hydrology, Numerical Analysis and Computation
Neural networks (NNs) enable precise modeling of complicated geophysical phenomena but are sensitive to small input changes. In this work, we present a new method for analyzing this instability in NNs. We focus our analysis on adversarial examples, test-time inputs with carefully-crafted human-imperceptible perturbations that expose the worst-case instability in a model's predictions. Our [...]
Slip-stuck kinematics of fault surfaces in laboratory experiments: implications for heterogeneous slip distributions during earthquake events
Published: 2023-05-05
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Combining field observations with analogue laboratory experiments, this study aims to use surface-roughness characteristics as an indicator of the heterogeneous slip partitioning along shear surfaces. We investigated the roughness of shear surfaces in sheared quartzite of the Singhbhum Shear Zone, eastern India, and identified two distinct kinematic domains: slip zone and stuck zone, marked by [...]
Lateral Heterogeneity Analysis Using Multiwell ZVSP Unsupervised Machine Learning Classification
Published: 2023-05-03
Subjects: Geophysics and Seismology
In 3D and 2D surface seismic interpretation, seismic waveform shapes and attributes can identify facies and reservoir parameters laterally with more details than traditional amplitude mapping. Herein, a method on 1D zero offset VSP (ZVSP) data was adapted, giving a unique perspective of lateral heterogeneity analysis using VSP seismic waveform shapes and attributes. The downgoing wavefield of VSP [...]
Active Learning with Deep Autoencoders for Seismic Facies Interpretation
Published: 2023-04-26
Subjects: Geophysics and Seismology
Machine learning-assisted seismic interpretation tasks require large quantities of labeled data annotated by expert interpreters, which is a costly and time-consuming process. Where existing works to minimize dependence on labeled data assume the data annotation process to already be completed, active learning---a field of machine learning---works by selecting the most important training samples [...]
A comparative study of transfer learning methodologies and causality for seismic inversion with temporal convolutional networks
Published: 2023-04-25
Subjects: Geophysics and Seismology
Machine learning-based seismic inversion methods suffer from high labeled data requirement in the absence of which they may fail to generalize. Recent data-driven inversion methodologies based on temporal convolutional networks use 2-D sequence models and transfer learning to unburden the algorithm from high training data requirements. Such methods are restricted in that they only model seismic [...]
In-situ frictional behavior of subducting sediment in the shallow Nankai Trough
Published: 2023-04-22
Subjects: Geology, Geophysics and Seismology, Sedimentology, Tectonics and Structure
The transition from smectite to illite at around the depth with temperature of ~150 °C has long been hypothesized as one of controlling factors of the updip limit depth of the seismogenic zone of subduction zones. Although illite has a higher friction coefficient than smectite, previous friction experiments have little reported that the smectite-illite transition accompanies the transition from [...]
Locating tectonic tremors with uncertainty estimates: Time- and amplitude-difference optimization, wave propagation-based quality control, and Bayesian inversion
Published: 2023-04-11
Subjects: Geophysics and Seismology
The accurate location of tectonic tremors helps improve understanding of their underlying physical processes. However, current location methods often do not statistically evaluate uncertainties to a satisfactory degree and do not account for potential biases due to subsurface structures not included in the model. To address these issues, we propose a novel three-step process for locating tectonic [...]
Consolidated Geothermal Database UK (CGD-UK): A digital open license database for temperature and thermal conductivity in the UK.
Published: 2023-04-08
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Natural Resource Economics, Oil, Gas, and Energy, Other Earth Sciences, Tectonics and Structure
Variations in subsurface heat flow within the upper crust control the distribution of geothermal resources. Development of a robust understanding of these variations requires reliable measurements of temperature and thermal conductivity. To date, measurements of temperature and conductivity onshore the UK have been unavailable in an accessible, clearly structured digital format. Here, we rectify [...]