Preprints
Filtering by Subject: Geophysics and Seismology
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 hindcasts paleo-trenches, through the spatiotemporal superposition of subducted lithosphere (slabs imaged in the earth’s mantle) with plate reconstructions (constrained by seafloor isochrons). The two geophysical datasets are linked through the tomotectonic null hypothesis, that oceanic lithosphere sinks vertically down after entering in the mantle. This linkage permits simple and [...]
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 [...]
Bridging the gap between SOLA and Deterministic Linear Inferences in the context of seismic tomography
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 inference methods make it possible to infer properties of the true Earth, providing useful insights into the internal structure of [...]
Quantifying relationships between fault parameters and rupture characteristics associated with thrust and reverse fault earthquakes.
Published: 2024-07-12
Subjects: Geology, Geomorphology, Geophysics and Seismology, Geotechnical Engineering, Risk Analysis, Tectonics and Structure
We investigate the influence of earthquake source characteristics and geological site parameters on fault scarp morphologies for thrust and reverse fault earthquakes using geomechanical models. We performed a total of 3,434 distinct element method (DEM) model experiments to evaluate the impact of the sediment depth, density, homogeneous and heterogeneous sediment strengths, fault dip, and the [...]
Fast and full characterization of large earthquakes from prompt elastogravity signals
Published: 2024-07-11
Subjects: Geophysics and Seismology
Prompt ElastoGravity Signals (PEGS) are light-speed gravity-induced signals recorded by seismometers before the arrival of seismic waves. They have raised interest for early warning applications but their weak amplitudes, close to the background seismic noise even for large earthquakes, have questioned PEGS actual potential for operational use. A deep-learning model has recently demonstrated its [...]
A non-equilibrium slurry model for planetary cores with application to Earth’s F-layer
Published: 2024-07-09
Subjects: Earth Sciences, Fluid Dynamics, Geophysics and Seismology, Mineral Physics
Slurry regions may exist in the cores of several terrestrial bodies and are expected to influence the dynamics of deep planetary interiors and the viability of maintaining global magnetic fields. Here we develop a two-component slurry model of the lowermost outer core of the Earth (the F-layer). In contrast to most previous models of slurries in planetary cores, we explicitly model the [...]
The sensitivity of lowermost mantle anisotropy to past mantle convection
Published: 2024-06-20
Subjects: Geophysics and Seismology, Mineral Physics
It is widely believed that seismic anisotropy in the lowermost mantle is caused by the flow-induced alignment of anisotropic crystals such as post-perovskite. What is unclear, however, is whether the anisotropy observations in the lowermost mantle hold information about past mantle flow, or if they only inform us about the present-day flow field. To investigate this, we compare the general and [...]
Predictive modelling of seismic properties in single-foliated slates
Published: 2024-06-17
Subjects: Earth Sciences, Geophysics and Seismology
Slates play a key role in understanding the seismic anisotropy of the continental crust, a crucial aspect of geophysical interpretation. Using a comprehensive set of high-quality single-foliated chlorite-bearing roofing slates, we determined their typical seismic properties via mineral fractions and orientation distribution functions using the geometric mean averaging method. Our study focused on [...]
Implementation of the Peruvian Earthquake Early Warning System
Published: 2024-06-12
Subjects: Artificial Intelligence and Robotics, Geophysics and Seismology
We present the implementation and testing of the seismological components of the Peruvian Earthquake Early Warning System (Sistema de Alerta Sísmica Peruano, SASPe). SASPe is designed to send alert messages to areas located within a given distance from the epicenter of large (magnitude ≥ 6.0) subduction earthquakes, with a first alert based on data available 3 seconds after the arrival [...]
Investigating the Dynamic History of a Promontory Ice Rise using Radar Data
Published: 2024-06-08
Subjects: Geophysics and Seismology, Glaciology
Ice rises hold valuable records revealing the ice dynamics and climatic history of Antarctic coastal areas from the Last Glacial Maximum to today. This history is often reconstructed from isochrone radar stratigraphy and simulations focusing on Raymond arch evolution beneath the divides. However, this relies on complex ice-flow models where many parameters are unconstrained by observations. Our [...]
Do large earthquakes start with a precursory phase of slow slip?
Published: 2024-06-07
Subjects: Geophysics and Seismology
In a recent publication, we showed that a stack of all GPS time series recorded before Magnitude ≥ 7.0 earthquakes suggests that large earthquakes start with a precursory phase of accelerating slow slip (Bletery and Nocquet, 2023). While no peer-reviewed comment or publication has formally contradicted this result, informal discussion has emerged on various platforms. We present here the [...]
Ensemble Kalman, Adaptive Gaussian Mixture, and Particle Flow Filters for Optimized Earthquake Forecasting
Published: 2024-06-01
Subjects: Dynamical Systems, Geophysics and Seismology, Other Statistics and Probability
Probabilistic forecasts are regarded as the highest achievable goal when predicting earthquakes, but limited information on stress, strength, and governing parameters of the seismogenic sources affects their accuracy. Ensemble data-assimilation methods, such as the Ensemble Kalman Filter (EnKF), estimate these variables by combining physics-based models and observations.While the EnKF has [...]
Unique composition and evolutionary histories of large low velocity provinces
Published: 2024-05-31
Subjects: Earth Sciences, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics
The two ``large low velocity provinces'' (LLVPs) are broad, low seismic wave speed anomalies in Earth's lower mantle beneath Africa and the Pacific Ocean. Recent research suggests they contain relatively dense subducted oceanic crust (SOC), but the relative concentration of this recycled material within them is an open question. Using simulations of 3-D global mantle circulation over the past 1 [...]