Preprints
Filtering by Subject: Geophysics and Seismology
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 [...]
Evaluation of the Grillo sensor, a low-cost accelerometer for IoT-based Real-time seismology
Published: 2021-01-02
Subjects: Geophysics and Seismology
Micro-Electro-Mechanical (MEMS) accelerometers are useful for real-time seismology due to their ability to record strong, unsaturated seismic signals. Recent advances in MEMS technologies enable design of instruments with improved capabilities that also allow recording of small signals. As a result, MEMS can be useful across a broad dynamic range and for both major earthquakes and smaller [...]
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 [...]
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 [...]
Evolution of a sand-rich submarine channel-lobe system and impact of mass-transport and transitional flow deposits on reservoir heterogeneity: Magnus Field, northern North Sea
Published: 2020-12-19
Subjects: Geology, Geophysics and Seismology, Sedimentology, Stratigraphy
The geometry, distribution, and rock properties (i.e. porosity and permeability) of turbidite reservoirs, and the processes associated with turbidity current deposition, are relatively well known. However, less attention has been given to the equivalent properties resulting from laminar sediment gravity-flow deposition, with most research limited to cogenetic turbidite-debrites (i.e. transitional [...]
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 [...]
The 2020 Mw 6.5 Monte Cristo Range, Nevada earthquake: relocated seismicity shows rupture of a complete shear-crack system
Published: 2020-12-18
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Tectonics and Structure
The predominant model for earthquake faulting is a shear crack, including surrounding damage zones. Observation of this complete shear crack system at seismogenic depth, however, has been elusive. Shear cracks with damage zones are related to fault formation and growth, and earthquake rupture physics and size, but observational and analytical limitations impede use of the shear crack paradigm in [...]
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 [...]
Quantitative uncertainty analysis of gravity disturbance. The case of the Geneva Basin (Switzerland)
Published: 2020-12-17
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Gravity data from the International Gravimetric Bureau and the Gravimetric Atlas of Switzerland have been used to evaluate their application and limitations as a subsurface investigation tool to constrain key geological structures in support of the georesources exploration in the Geneva Basin (GB). In this context, the application of an effective processing workflow able to produce a [...]
Initial model construction for intermediate-period full-waveform inversion of the contiguous US and surrounding regions
Published: 2020-12-15
Subjects: Geophysics and Seismology
Contiguous US is one of regions well instrumented with broadband seismic stations due to the deployment of the EarthScope Transportable Array. Previous studies have provided various 3D seismic wave speed models for the crust and upper mantle with improving resolution. However, discrepancies exist between these models due to the differences in both data sets and tomographic methods, which [...]
Anatomy of Strike Slip Fault Tsunami-genesis
Published: 2020-12-13
Subjects: Earth Sciences, Engineering, Fluid Dynamics, Geophysics and Seismology, Physical Sciences and Mathematics, Physics
Tsunami generation from earthquake induced seafloor deformations has long been recognized as a major hazard to coastal areas. Strike-slip faulting has generally been believed as insufficient for triggering large tsunamis, except through the generation of submarine landslides. Herein, we demonstrate that ground motions due to strike-slip earthquakes can contribute to the emergence of large [...]
Coordination numbers in natural beach sand
Published: 2020-12-02
Subjects: Geophysics and Seismology, Geotechnical Engineering, Sedimentology
Coordination number controls elastic moduli, seismic velocity, and force transmission in sands and is thus a critical factor controlling the resistance of sands to deformation. Previous studies quantified relationships between coordination number, porosity, grain size, sphericity, and effective stress in pluviated or modeled sands. Here, we determine if these relationships hold in [...]
Recording earthquakes for tomographic imaging of the mantle beneath the South Pacific by autonomous MERMAID floats
Published: 2020-12-02
Subjects: Geophysics and Seismology
We present the first 16 months of data returned from a mobile array of 16 freely floating diving instruments, named MERMAID for Mobile Earthquake Recording in Marine Areas by Independent Divers, launched in French Polynesia in late 2018. Our 16 are a subset of the 50 MERMAID deployed over a number of cruises in this vast and understudied oceanic province as part of the collaborative South Pacific [...]
Double-difference earthquake relocation using waveform cross-correlation in Central and East Java, Indonesia (Preprint)
Published: 2020-11-25
Subjects: Earth Sciences, Geophysics and Seismology
The Central and East Java region, which is part of the Sunda Arc, has relatively high seismic rates due to the convergence of two major tectonic plates in the Indonesian region; i.e., the Indo-Australian Plate subducting under the Eurasian Plate. Many devastating earthquakes have occurred in this area as a result of the interaction between these two plates. Two examples are the 1994 Banyuwangi [...]
Deformation memory in the lithosphere: A comparison of damage-dependent weakening and grain-size sensitive rheologies
Published: 2020-11-25
Subjects: Earth Sciences, Geophysics and Seismology
Strain localization in the lithosphere and the formation, evolution, and maintenance of resulting plate boundaries play a crucial role in plate tectonics and thermo-chemical mantle convection. Previously activated lithospheric deformation zones often appear to maintain a “memory” of weakening, leading to tectonic inheritance within plate reorganizations including the Wilson cycle. Different [...]