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Aftershock analysis challenges world's deepest earthquake claim

Phys.org: Earth science - Wed, 01/22/2025 - 21:35

The magnitude 7.9 Bonin Islands earthquake sequence in May 2015, which ruptured deep within the earth near the base of the upper mantle, did not include an aftershock that extended to record depths into the lower mantle, according to a study appearing in The Seismic Record.

Overlooking a low-hanging fruit in climate mitigation: Biochar has been underestimated, say researchers

Phys.org: Earth science - Wed, 01/22/2025 - 21:20

A new study shows biochar to be far more effective at long-term carbon storage than previously thought. The study reveals critical flaws in the models used by the IPCC and European climate policymakers.

AI enables innovation in glacier modeling and offers simulation of last Alpine glaciation

Phys.org: Earth science - Wed, 01/22/2025 - 17:55

Scientists at the University of Lausanne (UNIL) have used AI to massively speed up computer calculations and simulate the last ice cover in the Alps. Much more in line with field observations, the new results show that the ice was thinner than in previous models. This innovative method opens the door to countless new simulations and predictions linked to climate upheavals. The research is published in Nature Communications.

Thawing permafrost helped trigger ancient Icelandic landslides, new research shows

Phys.org: Earth science - Wed, 01/22/2025 - 16:37

When glaciers and ice sheets melt, they can destabilize slopes and reactivate faults, which in turn can trigger landslides and reshape the surface of Earth over long periods of time. Researchers can monitor some locations in real time to determine which combinations of factors lead to landslides, but understanding what triggered landslides thousands of years ago is more difficult.

Seismic study reveals ancient 'islands' deep within Earth's mantle

Phys.org: Earth science - Wed, 01/22/2025 - 16:00

Deeply hidden in Earth's mantle there are two huge "islands" the size of a continent. New research from Utrecht University shows that these regions are not only hotter than the surrounding graveyard of cold sunken tectonic plates, but also that they must be ancient: at least half a billion years old, perhaps even older.

Here's what's causing the Great Salt Lake to shrink, according to study

Phys.org: Earth science - Wed, 01/22/2025 - 15:28

The Great Salt Lake, the largest saltwater lake in the Western Hemisphere, reached historic low levels in 2022, raising economic, ecological and public health concerns for Utah.

Evaluating ion dynamics through Coulomb and Yukawa interaction potentials in one-component strongly coupled plasmas

Physical Review E (Plasma physics) - Wed, 01/22/2025 - 10:00

Author(s): Swati Swagatika Mishra, Sudeep Bhattacharjee, and Pascal Brault

Atmospheric pressure helium plasmas are investigated through molecular dynamics simulations at room temperature (300 K) for various ionization fractions (χi=10−1−10−5) in the strongly coupled regime (ion coupling parameter, Γi∼1−10) employing Coulomb and Yukawa interaction potentials. The role of el…

[Phys. Rev. E 111, 015208] Published Wed Jan 22, 2025

Generative-machine-learning surrogate model of plasma turbulence

Physical Review E (Plasma physics) - Wed, 01/22/2025 - 10:00

Author(s): B. Clavier, D. Zarzoso, D. del-Castillo-Negrete, and E. Frénod

Generative artificial intelligence methods are employed for the first time to construct a surrogate model for plasma turbulence that enables long-time transport simulations. The proposed GAIT (Generative Artificial Intelligence Turbulence) model is based on the coupling of a convolutional variationa…

[Phys. Rev. E 111, L013202] Published Wed Jan 22, 2025

Millennial axially-symmetric Magneto-Coriolis modes in Earth’s fluid core

Geophysical Journal International - Wed, 01/22/2025 - 00:00

SummaryMagneto-Coriolis (MC) modes in Earth’s fluid core involve oscillations sustained by the combined effect of the Lorentz and Coriolis forces. Here, we investigate the properties of MC modes that involve purely axisymmetric flow, which we term axiMC modes. We provide a basic description of the wave dynamics of these modes, and simple predictions for the expected scalings of their frequency ω, decay rate λ, and quality factor Q based on a uniform ambient magnetic field. In particular, Q scales with the Elsasser number Λ, which depends on the square of the r.m.s. strength of the azimuthally averaged meridional field. When Λ > 1, Q > 1 and axiMC modes may be excited; when Λ ≪ 1, Q ≪ 1 and axiMC modes revert to quasi-free magnetic decay modes. We present computations of axiMC modes in an inviscid, electrically conducting sphere for two idealized ambient magnetic field configurations, a uniform axial field and an axial poloidal field. We show that a flow gradient in the axial direction is a key property of axiMC modes. For the uniform axial field, ω, λ and Q follow the scalings expected for a uniform field. For the axial poloidal field, the structure of the modes changes substantially when Λ ≳ 1, becoming more concentrated in regions of lower field strength. The combination of this structural change and advection of field lines by flow significantly increases λ, resulting in a Q that remains close to 1 even at high Λ. For a magnetic field strength inside the Earth’s core of a few mT, the gravest axiMC modes are expected to have periods in the range of one thousand to a few thousand years and a Q not substantially above 1. AxiMC modes may be connected to a part of the observed millennial changes in Earth’s magnetic field, may exchange axial angular momentum with the mantle, and hence may also explain a part of the observed millennial changes in length of day.

Efficient analytical partial derivatives of modal phase velocity with respect to layer parameters

Geophysical Journal International - Wed, 01/22/2025 - 00:00

SummaryMulti-channel analysis of surface wave (MASW) is a non-destructive technique to characterize the sub-surface using the dispersive nature of Rayleigh waves. Field dispersion curves are inverted to predict the shear wave velocity structure of the ground and pavement profile. Adjusting the dynamic properties of the initially assumed soil profile necessitates information regarding the dominant sensitive layers. Therefore, a swift and accurate computation of the Jacobian of phase velocity is essential to generate an appropriate shear wave velocity profile and accelerate the inversion process. This is especially crucial for the 2D MASW survey, which requires hundreds of 1D inversions to create a high resolution 2D profile. Available numerical methods are computationally expensive and often suffer from instabilities for highly sensitive layers. The existing analytical methods involve mathematical complexities and require rigorous treatment. Furthermore, they are time-consuming and often found to be marginally faster than the numerical methods. Based on the fast delta matrix algorithm, the paper presents a new efficient analytical formulation of the Jacobian matrix of modal phase velocities concerning the layer parameters. The proposed algorithm leverages the simpler and fewer matrix elements of the fast delta matrix, thus significantly reducing the number of mathematical operations required. Additionally, it reduces the algorithm's cost by factorizing non-zero elements, thereby markedly reducing the computational time. Five different types of synthetic earth models are adopted from the published literature to validate the accuracy and efficacy of the newly developed algorithm. The presented work will significantly benefit the practicing engineers and geophysicists in processing field MASW test data.