Preprints
Filtering by Subject: Geophysics and Seismology
A new expression for fluid factor using AVO intercept and gradient: theory and application on deep marine reservoir
Published: 2024-09-18
Subjects: Geology, Geophysics and Seismology, Oil, Gas, and Energy
Numerous AVO fluid indicators have been introduced and proven to be sensitive to hydrocarbon presence. Mathematically, fluid indicators measure the deviation of seismic responses of hydrocarbon-saturated reservoirs from their background in a specific domain. We introduce a new expression for the fluid factor commonly used in AVO analysis and interpretation. The expression is a function of common [...]
Evidence supporting a broader than previously thought influence of solar activity over Earth system’s processes. Discussion of a possible mechanism.
Published: 2024-09-08
Subjects: Atmospheric Sciences, Earth Sciences, Geochemistry, Geology, Geophysics and Seismology, Meteorology, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Tectonics and Structure, Volcanology
In this article, I show lines of evidence supporting a modulation of volcanic activity and some weather phenomena by solar wind conditions in the near-Earth environment. On a daily timescale, a correlation is found between the LP earthquake activity of Kilauea volcano, related to magma transport, and the Bx component of the interplanetary magnetic field as measured in the OMNI database for [...]
The formation and evolution of Earth’s inner core.
Published: 2024-09-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Growth of the inner core provides crucial power for generating the geomagnetic field and preserves a unique record of deep Earth evolution. The classical picture of inner core growth ignores the fact that the liquid core must have been supercooled below its melting temperature to spontaneously freeze the inner core. In this review we assess the impact of supercooling on inner core formation, [...]
Distinguishing natural sources from anthropogenic noise in seismic data
Published: 2024-08-30
Subjects: Earth Sciences, Geophysics and Seismology
Towards a widely applicable earthquake detection algorithm for fibreoptic and hybrid fibreoptic-seismometer networks
Published: 2024-08-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Distributed Acoustic Sensing (DAS) is a promising technology for providing dense (metre-scale) sampling of the seismic wavefield. However, harnessing this potential for earthquake detection with accurate phase picking and associated localisation remains challenging. Single-channel algorithms are limited by individual channel noise, while machine learning and semblance methods are typically [...]
Frictional Properties of Simulated Fault Gouges subject to Normal Stress Oscillation and Implications for Induced Seismicity
Published: 2024-08-24
Subjects: Geophysics and Seismology, Oil, Gas, and Energy, Risk Analysis
Under critical conditions where experimental fault slip exhibits self-sustained oscillation, effects of normal stress oscillation (NSO) on fault strength and stability remain poorly understood, as do potential effects of NSO on natural and induced seismicity. In this study, we employed double direct shear testing to investigate the frictional behavior of a synthetic, slightly velocity-weakening [...]
Array-based seismic measurements of OSIRIS-REx's re-entry
Published: 2024-08-23
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Planetary Sciences
The return home of the OSIRIS-REx spacecraft in September 2023 marked only the fifth time that an artificial object entered the Earth's atmosphere at interplanetary velocities. Although rare, such events serve as valuable analogues for natural meteoroid re-entries; enabling study of hypersonic dynamics, shockwave generation, and acoustic-to-seismic coupling. Here, we report on the signatures [...]
Complex and confined laboratory ruptures explain scaling of the critical slip distance for earthquake faulting
Published: 2024-08-22
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Earthquake sequences in nature are complex, exhibiting a range of magnitudes and slip behaviors. In contrast, earthquake-like instabilities generated on frictional faults in the laboratory and in continuum numerical models are usually quasi-periodic with a smaller range of magnitudes and durations. The discrepancy, especially apparent for cm-sized samples used in lab friction experiments, has [...]
Partial ruptures governed by the complex interplay between geodetic slip deficit, rigidity, and pore fluid pressure in 3D Cascadia dynamic rupture simulations
Published: 2024-08-14
Subjects: Geophysics and Seismology
Physics-based simulations are crucial to assessing the seismic hazard in the Cascadia subduction zone (CSZ), requiring assumptions about fault stress and material properties. Geodetic slip deficit models (SDMs) may inform the initial stresses governing megathrust earthquake dynamics. We present a unified workflow linking SDMs to 3D dynamic rupture simulations, and 22 rupture scenarios to unravel [...]
Constraining Earth's core composition from inner core nucleation.
Published: 2024-08-02
Subjects: Earth Sciences, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Mineral Physics, Planetary Sciences
Mesoscale fractures control the scale dependences of seismic velocity and fluid flow in subduction zones
Published: 2024-07-27
Subjects: Geophysics and Seismology
Natural geological systems contain porosity structures of various scales that play different roles in geophysical properties, fluid flow, and geodynamics. To understand seismic activity associated with high pore-fluid pressure and fluid migration in subduction zones, it is necessary to explore the scale dependence of geophysical properties such as seismic velocity and permeability. Here, we [...]
Tomotectonics of Cordilleran North America since Jurassic times: double-sided subduction, archipelago collisions, and Baja-BC translation
Published: 2024-07-27
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Tomotectonics uses deep mantle structure in order to hindcast paleo-trenches, by spatially superposing subducted lithosphere (slabs) imaged by seismic tomography with plate reconstructions at the surface. The two geophysical datasets combined make predictions about geologic events, specifically about volcanic arcs and their collisions with continents. The tomotectonic null hypothesis is simple, [...]
Volcanic arc structure controlled by liquid focusing from the slab — evidence from boron isotopes and trace elements
Published: 2024-07-16
Subjects: Earth Sciences, Geochemistry, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
The rates and pathways of material transport from subducting plates to arc volcanoes control the long-term chemical evolution of the atmosphere, continents, and mantle. Arc magma compositions are commonly used as proxies for the state of the slab directly below a volcanic vent, under the assumption of vertical transport from the slab to the surface. Here, we present new boron (B) isotope and [...]
Rupture directivity from energy envelope deconvolution: theory and application to 69 Ridgecrest M 3.5–5.5 earthquakes
Published: 2024-07-13
Subjects: Geophysics and Seismology
Earthquake rupture directivity impacts ground motions and provides important insights on fault zone properties and earthquake physics. However, measuring directivity of small earthquakes is challenging due to their compact rupture sizes and complex path and site effects at high frequencies. Here, we develop a new approach that deconvolves energy envelopes of the S-coda waves to remove path and [...]
Constraining Earth Properties using Deterministic Backus-Gilbert Inferences
Published: 2024-07-12
Subjects: Geophysics and Seismology
Seismic tomography is routinely used to image the Earth’s interior using seismic data. However, in practice, data limitations lead to discretised inversions or the use of regularisations, which complicates tomographic model interpretations. In contrast, Backus-Gilbert methods make it possible to infer properties of the true Earth, providing useful insights into the internal structure of our [...]