A re-examination of the 2015 Bonin Islands earthquake disproved earlier claims of a record-breaking deep aftershock in the lower mantle, identifying instead 14 aftershocks linked to a metastable olivine wedge in the upper mantle. This finding advances understanding of deep earthquake mechanisms and Earth’s interior dynamics.

A study published in The Seismic Record challenges previous reports about the May 2015 magnitude 7.9 Bonin Islands earthquake sequence. The main earthquake, which ruptured deep near the base of the upper mantle, was not followed by an aftershock extending into the lower mantle to record-breaking depths, as earlier claims suggested.

Hao Zhang of the University of Southern California and colleagues re-analyzed the aftershock sequence and found no evidence of a 751-kilometer-deep aftershock, previously described as the deepest earthquake ever recorded.

Polarization is a key parameter in light–matter interactions and is consequently closely linked to light manipulation, detection, and analysis. Terahertz (THz) waves, characterized by their broad bandwidth and long wavelength, pose significant challenges to efficient polarization control with existing technologies. Here, we leverage the mesoscale wavelength characteristics of THz waves and employ a mirror-coupled total internal reflection structure to mechanically modulate the phase difference between p-and s-waves by up to 289°. By incorporating a liquid crystal phase shifter to provide adaptive phase compensation, dispersion is eliminated across a broad bandwidth. We demonstrate active switching of orthogonal linear polarizations and handedness-selective quarter-wave conversions in the 1.6–3.4 THz range, achieving an average degree of linear/circular polarization exceeding 0.996. Furthermore, arbitrary polarization at any center frequency is achieved with a fractional bandwidth exceeding 90%. This customizable-bandwidth and multifunctional device offers an accurate and universal polarization control solution for various THz systems, paving the way for numerous polarization-sensitive applications.

When Things Start Disappearing in the Universe without a trace. My Patreon Page: https://www.patreon.com/johnmichaelgodierMy Event Horizon Channel: https://www.youtube.com/img/desktop/supported_browsers/yt_logo_rgb_light.png

One step closer to nuclear fusion with its first plasma.

face_with_colon_three Year 2012

Elevated land-based islands could protect people living in low-lying areas from tsunamis – and archipelagos of them could form entire towns.

By Robert Gilhooly

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Understanding how people perceive and interpret uncertainty from large language models (LLMs) is crucial, as users often overestimate LLM accuracy, especially with default explanations. Steyvers et al. show that aligning LLM explanations with their internal confidence improves user perception.