Filtering by Subject: Geophysics and Seismology

Volcanic arc structure controlled by liquid focusing from the slab — evidence from boron isotopes and trace elements

Stephen J Turner, Ivan Savov, Tamsin Mather, et al.

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

Zhe Jia, Peter M. Shearer, Wenyuan Fan

Published: 2024-07-12
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

Adrian Marin Mag, Christophe Zaroli, Paula Koelemeijer

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 [...]

Quantifying relationships between fault parameters and rupture characteristics associated with thrust and reverse fault earthquakes.

Kristen Chiama, William Bednarz, Robb Moss, et al.

Published: 2024-07-11
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

Kévin Juhel, Quentin Bletery, Andrea Licciardi, et al.

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

Andrew Walker, Chris Davies, Alfred Wilson, et al.

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 physics [...]

The sensitivity of lowermost mantle anisotropy to past mantle convection

James A Ward, Andrew Walker, Andy Nowacki, et al.

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

Marco Antonio Lopez-Sanchez, Víctor Cárdenes Van den Eynde, Fabrice Barou, et al.

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 roofing slates, we determined their typical seismic properties via mineral fractions and orientation distribution functions using the VRH averaging method. Our study focused on identifying optimal polar [...]

Implementation of the Peruvian Earthquake Early Warning System

Pablo Lara, Hernando Tavera, Quentin Bletery, et al.

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

M. Reza Ershadi, Reinhard Drews, Jean-Louis TISON, et al.

Published: 2024-06-07
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?

Quentin Bletery, Jean-Mathieu Nocquet

Published: 2024-06-06
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

Hamed Ali Diab-Montero, Andreas S. Stordal, Peter Jan van Leeuwen, et al.

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 low velocity mantle domains

James Panton, J. Huw Davies, Paula Koelemeijer, et al.

Published: 2024-05-30
Subjects: Earth Sciences, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics

The two `large low velocity provinces' (LLVPs) are broad seismic wave speed anomalies in Earth's lower mantle beneath Africa and the Pacific Ocean. Recent research suggests they represent volumes that contain relatively dense subducted oceanic crust (SOC), but the distribution of recycled material within them is an open question. Using simulations of 3-D global-scale mantle circulation over the [...]

Ringing mountain ranges: Teleseismic signature of the interaction of high-frequency wavefields with near-source topography at the Degelen nuclear test site

Marta Pienkowska, Stuart E. J. Nippress, David Bowers, et al.

Published: 2024-05-26
Subjects: Geophysics and Seismology

Over the last decade there has been an international effort to find methods to recover and digitize recordings from historical earthquakes and explosions that occurred during the 1950’s through to the 1980’s. Making these recordings accessible in digital format offers opportunities to study what signatures are encoded in the data, and to apply state-of-the-art techniques and methods to historical [...]

Predictable recovery rates in near-surface materials after earthquake damage

Luc Illien, Jens Martin Turowski, Christoph Sens-Schönfelder, et al.

Published: 2024-05-23
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Earthquakes introduce transient mechanical damage in the subsurface, which causes postseismic hazards and can take years to recover. This observation has been linked to relaxation, a phenomenon observed in a wide class of materials after straining perturbations, but its duration after earthquake ground shaking has not been constrained. Here, we analyse the effects of two successive large [...]


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