Preprints

Filtering by Subject: Geophysics and Seismology

Shear-wave Anisotropy in the Earth’s Inner Core

Sheng Wang, Hrvoje Tkalčić

Published: 2021-09-17
Subjects: Earth Sciences, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics

Earth’s inner core anisotropy is widely used to infer the deep Earth's evolution and present dynamics. Many compressional-wave anisotropy models have been proposed based on seismological observations. In contrast, inner-core shear-wave (J-wave) anisotropy – on a par with the compressional-wave anisotropy – has been elusive. Here we present a new class of the J-wave anisotropy observations [...]

Stress-based forecasting of induced seismicity with instantaneous earthquake failure functions: Applications to the Groningen Gas Reservoir.

Jonathan Daniel Smith, Elias Rafn Heimisson, Stephen Bourne, et al.

Published: 2021-09-15
Subjects: Geophysics and Seismology

The Groningen gas field is a natural laboratory to test stress-based forecasting models of induced seismicity due to the detailed knowledge of the reservoir geometry and production history, as well as the availability of surface subsidence measurements and high quality seismicity data. A specific feature of that case example is the exponential rise of seismicity that was detected nearly 30 years [...]

Three-dimensional fluid-driven stable frictional ruptures

Alexis Sáez, Brice Lecampion, Pathikrit Bhattacharya, et al.

Published: 2021-09-13
Subjects: Earth Sciences, Engineering, Environmental Sciences, Geophysics and Seismology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Physics

We investigate the quasi-static growth of a fluid-driven frictional shear crack that propagates in mixed mode (II+III) on a planar fault interface that separates two identical half-spaces of a three-dimensional solid. The fault interface is characterized by a shear strength equal to the product of a constant friction coefficient and the local effective normal stress. Fluid is injected into the [...]

Assessment pebble virtual velocity from combined active RFID fixed stations and geophones

Mathieu Cassel, Hervé Piégay, Oldrich Navratil, et al.

Published: 2021-09-06
Subjects: Geomorphology, Geophysics and Seismology, Hydrology

The monitoring of coarse sediment transport is a domain teeming with technical innovations and methodological developments aimed at improving the characterization of bedload processes at different spatial and temporal scales. Radio frequency identification (RFID) technology has improved sediment tracking experiments, allowing the characterization of processes at the individual particle and [...]

Drone-mounted GPR surveying: flight-height considerations for diffraction-based velocity analysis

Adam Booth, Tiffany Koylass

Published: 2021-09-06
Subjects: Earth Sciences, Geophysics and Seismology, Other Earth Sciences

Recent studies highlight the potential of the drone platform for ground penetrating radar (GPR) surveying. Most guidance for optimising drone flight-heights is based on maximising the image quality of target responses, but no study yet considers the impact on diffraction travel-times. Strong GPR velocity contrasts across the air-ground interface introduce significant refraction effects that [...]

An overview of multimethod imaging approaches in environmental geophysics

Florian M. Wagner, Sebastian Uhlemann

Published: 2021-08-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Quantitative characterization of subsurface properties is critical for many environmental applications and serves as the basis to simulate and better understand dynamic subsurface processes. Geophysical imaging methods allow to image subsurface property distributions and monitor their spatio-temporal changes in a minimally invasive manner. While it is widely agreed upon that models integrating [...]

Fault rock heterogeneity produces fault weakness and promotes unstable slip

John Bedford, Daniel Faulkner, Nadia Lapusta

Published: 2021-08-30
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Tectonics and Structure

Geological heterogeneity is abundant in crustal fault zones; however, its role in controlling the mechanical behaviour of faults is poorly constrained. Here, we present laboratory friction experiments on laterally heterogeneous faults, with patches of strong, rate-weakening quartz gouge and weak, rate-strengthening clay gouge. The experiments show that the heterogeneity leads to a significant [...]

Viscous fault creep controls the stress-dependence of modelled earthquake statistics

Adam Beall, Martijn van den Ende, Jean-Paul Ampuero, et al.

Published: 2021-08-27
Subjects: Geophysics and Seismology

The ability to estimate the likelihood of particular earthquake magnitudes occurring in a given region is critical for seismic hazard assessment. Earthquake size and recurrence statistics have been empirically linked to stress state, however there is ongoing debate as to which fault-zone processes are responsible for this link. We numerically model combined viscous creep and frictional sliding of [...]

Parsimonious velocity inversion applied to the Los Angeles Basin, CA

Jack Broderick Muir, Robert W Clayton, Victor C. Tsai, et al.

Published: 2021-08-24
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

The proliferation of dense arrays promises to improve our ability to image geological structures at the scales necessary for accurate assessment of seismic hazard. However, combining the resulting local high-resolution tomography with existing regional models presents an ongoing challenge. We developed a framework based on the level-set method that provides a means to infer where local data [...]

Spectral boundary integral method for simulating static and dynamic fields from a fault rupture in a poroelastodynamic solid

Elias Rafn Heimisson, Antonio Pio Rinaldi

Published: 2021-08-24
Subjects: Applied Mechanics, Geophysics and Seismology, Partial Differential Equations, Tribology

The spectral boundary integral method is popular for simulating fault, fracture, and frictional processes at a planar interface. However, the method is less commonly used to simulate off-fault dynamic fields. Here we develop a spectral boundary integral method for poroelastodynamic solid. The method has two steps: first, a numerical approximation of a convolution kernel and second, an efficient [...]

The Optimal Correlation Detector?

Steven John Gibbons

Published: 2021-08-19
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Correlation detectors are now used routinely in seismology to detect occurrences of signals bearing close resemblance to a reference waveform. They facilitate the detection of low-amplitude signals in significant background noise that may elude detection using energy detectors, and they associate a detected signal with a source location. Many seismologists use the fully normalized correlation [...]

Safety and Belonging in the Field: A Checklist for Educators

Sarah E Greene, Gwen S. Antell, Jake Atterby, et al.

Published: 2021-08-19
Subjects: Atmospheric Sciences, Biogeochemistry, Climate, Cosmochemistry, Earth Sciences, Education, Environmental Education, Environmental Health and Protection, Environmental Indicators and Impact Assessment, Environmental Monitoring, Environmental Sciences, Environmental Studies, Fresh Water Studies, Geochemistry, Geographic Information Sciences, Geography, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Higher Education, Human Geography, Hydrology, Life Sciences, Meteorology, Mineral Physics, Natural Resource Economics, Natural Resources and Conservation, Natural Resources Management and Policy, Nature and Society Relations, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Oil, Gas, and Energy, Other Earth Sciences, Other Environmental Sciences, Other Geography, Other Oceanography and Atmospheric Sciences and Meteorology, Other Planetary Sciences, Outdoor Education, Paleobiology, Paleontology, Physical and Environmental Geography, Physical Sciences and Mathematics, Planetary Biogeochemistry, Planetary Geochemistry, Planetary Geology, Planetary Geomorphology, Planetary Geophysics and Seismology, Planetary Glaciology, Planetary Hydrology, Planetary Mineral Physics, Planetary Sciences, Planetary Sedimentology, Remote Sensing, Sedimentology, Social and Behavioral Sciences, Soil Science, Spatial Science, Speleology, Stratigraphy, Sustainability, Tectonics and Structure, Volcanology, Water Resource Management

Ensuring taught fieldwork is a positive, generative, collective, and valuable experience for all participants requires considerations beyond course content. To guarantee safety and belonging, participants’ identities (backgrounds and protected characteristics) must be considered as a part of fieldwork planning and implementation. Furthermore, getting fieldwork right is an important step in [...]

Reflection Seismic Thermometry

Arka Dyuti Sarkar, Mads Huuse

Published: 2021-08-12
Subjects: Geology, Geophysics and Seismology

The North Viking Graben (NVG) is part of the mature North Sea Basin petroleum province and designated as a major carbon storage basin for NW Europe. It has been extensively drilled over five decades with an abundance of well and seismic data in the public domain. As such it serves as an excellent setting to demonstrate the efficacy of a reflection seismic data led approach to predicting [...]

The world’s second-largest, recorded landslide event: lessons learnt from the landslides triggered during and after the 2018 Mw 7.5 Papua New Guinea earthquake

Hakan Tanyas, Kevin Hill, Luke Mahoney, et al.

Published: 2021-07-30
Subjects: Geology, Geomorphology, Geophysics and Seismology, Hydrology, Other Earth Sciences

Widespread landslide events provide rare but valuable opportunities to investigate the spatial and size distributions of landslides in relation to seismic, climatic, geological and morphological factors. This study presents a unique event inventory for the co-seismic landslides induced by the February 25, 2018 Mw 7.5 Papua New Guinea earthquake as well as its post-seismic counterparts including [...]

Probabilistic near-field tsunami source and tsunami run-up distribution inferred from tsunami run-up records in northern Chile

Jun-Whan Lee, Jennifer Irish, Robert Weiss

Published: 2021-07-27
Subjects: Civil and Environmental Engineering, Geophysics and Seismology, Other Oceanography and Atmospheric Sciences and Meteorology

Understanding a tsunami source and its impact is vital to assess a tsunami hazard. Thanks to the efforts of the tsunami survey teams, high-quality tsunami run-up data exists for contemporary events. Still, it has not been widely used to infer a tsunami source and its impact mainly due to the computational burden of the tsunami forward model. In this study, we propose a TRRF-INV (Tsunami Run-up [...]

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