Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake

The M[JMA]7.3 Kumamoto earthquake occurred on April 16, 2016, in the western part of Kyushu, at a depth of 12 km, on an active strike-slip fault. Here, we report on a relatively widespread activation of small remote earthquakes, which occurred as far as Hokkaido, detected by analyzing the continuous waveform data recorded at seismic stations all over Japan. Such relatively widespread remote seismicity activation, following a large inland earthquake, has not been reported before for Japan. Our analysis demonstrates that the remote events were triggered dynamically, by the passage of the surface waves from the Kumamoto earthquake. Most of the remotely triggered events in the Tohoku and Hokkaido regions, as well as close to Izu Peninsula, occur at or close to volcanoes, which suggests that the excitation of crustal fluids, by the passage of Rayleigh waves, played an important triggering role. Nevertheless, remote activation in other regions, like Noto Peninsula, occurred away from volcanoes. The relatively large-amplitude Love waves, enhanced by a source directivity effect during the Kumamoto earthquake, may have triggered seismicity on local active faults. The dynamic stresses in the areas where remote activation has been observed range from several kPa to tens of kPa, the thresholds being lower than in previous dynamic triggering cases for Japan; this might relate to a change in the crustal conditions following the 2011 M9.0 Tohoku-oki earthquake, in particular at volcanoes in NE Japan

Nucleation process of the 2011 northern Nagano earthquake from nearby seismic observations

東北地方太平洋沖地震後に日本全国で発生した誘発地震のメカニズムを解析 --稠密地震観測網で捉えられた長野県北部の地震の前駆過程--. 京都大学プレスリリース. 2021-04-19.High-density seismic network detected inland earthquake precursors. 京都大学プレスリリース. 2021-05-10.The 2011 magnitude (M) 9.0 Tohoku-oki earthquake was followed by seismicity activation in inland areas throughout Japan. An outstanding case is the M6.2 Northern Nagano earthquake, central Japan, occurred 13-h after the megathrust event, approximately 400 km away from its epicenter. The physical processes relating the occurrence of megathrust earthquakes and subsequent activation of relatively large inland earthquakes are not well understood. Here we use waveform data of a dense local seismic network to reveal with an unprecedented resolution the complex mechanisms leading to the occurrence of the M6.2 earthquake. We show that previously undetected small earthquakes initiated along the Nagano earthquake source fault at relatively short times after the Tohoku-oki megathrust earthquake, and the local seismicity continued intermittently until the occurrence of the M6.2 event, being likely ‘modulated’ by the arrival of surface waves from large, remote aftershocks off-shore Tohoku. About 1-h before the Nagano earthquake, there was an acceleration of micro-seismicity migrating towards its hypocenter. Migration speeds indicate potential localized slow-slip, culminating with the occurrence of the large inland earthquake, with fluids playing a seismicity-activation role at a regional scale

Polymorphism of β2-Microglobulin Amyloid Fibrils Manifested by Ultrasonication-enhanced Fibril Formation in Trifluoroethanol

This research was originally published in the Journal of Biological Chemistry. Eri Chatani, Hisashi Yagi, Hironobu Naiki and Yuji Goto. Polymorphism of β2-Microglobulin Amyloid Fibrils Manifested by Ultrasonication-enhanced Fibril Formation in Trifluoroethanol. J. Biol. Chem. 2012; 287, 22827-22837. © the American Society for Biochemistry and Molecular Biolog

Multi‐Scale Rupture Growth With Alternating Directions in a Complex Fault Network During the 2023 South‐Eastern Türkiye and Syria Earthquake Doublet

A devastating doublet of earthquakes with moment magnitude MW 7.9 and MW 7.6 earthquakes contiguously occurred in SE Türkiye near the NW border of Syria. Here we perform a potency-density tensor inversion to simultaneously estimate rupture evolution and fault geometry for the doublet. We find the initial MW 7.9 earthquake involved discrete episodes of supershear rupture and back-rupture propagation, and was triggered by initial rupture along a bifurcated splay of the East Anatolian Fault. The second MW 7.6 event was triggered by the earlier MW 7.9 event, and it involved more extensive supershear rupture along a favorably curved fault, and was likely stopped by geometric barriers at the fault ends. Our results highlight the multi-scale cascading rupture growth across the complex fault network that affects the diverse rupture geometries of the 2023 Türkiye earthquake doublet, contributing to the strong ground shaking and associated devastation

DEDE-type little strings from glued brane webs

We propose brane web configurations for $D$-type and $E$-type $\mathcal{N}=(1,0)$ little string theories based on a trivalent or quadrivalent gluing of 5-brane web diagrams. Tri-/quadri-valent gluing is a powerful way of computing 5d/6d partition functions for supersymmetric gauge theories based on the topological vertex. We generalize the gluing techniques to little string theories by introducing a new compact direction and compute their supersymmetric partition functions on Omega-deformed $\mathbb{R}^4\times T^2$. As concrete examples, we consider little string theories arising from Type IIB NS5-branes probing $D_4$ or $D_5$ singularity. Their effective gauge theory descriptions as the affine $D_4$ or $D_5$ quiver gauge theory can be realized with quadrivalent or trivalent gluing, respectively. Based on these gluings of 5-brane webs, we compute their refined partition functions and compare them with the known results. We extend the computation of the partition function to little string theory engineered from IIB NS5-branes probing $E_6$ singularity based on a trivalent gluing. We also discuss the generalization to higher rank cases and the symmetries of the partition functions.Comment: v2: 97 pages, 32 figures, typos corrected and clarifications adde

Benzalkonium Chloride Accelerates the Formation of the Amyloid Fibrils of Corneal Dystrophy-associated Peptides

This research was originally published in the Journal of Biological Chemistry. Yusuke Kato, Hisashi Yagi, Yuichi Kaji, Tetsuro Oshika and Yuji Goto. Benzalkonium Chloride Accelerates the Formation of the Amyloid Fibrils of Corneal Dystrophy-associated Peptides. J. Biol. Chem. 2013; 288, 25109-25118. © the American Society for Biochemistry and Molecular Biolog

Characteristics of foreshock activity inferred from the JMA earthquake catalog

We investigated the foreshock activity characteristics using the Japan Meteorological Agency Unified Earthquake Catalog for the last 20 years. Using the nearest-neighbor distance approach, we systematically and objectively classified the earthquakes into clustered and background seismicity. We further categorized the clustered events into foreshocks, mainshocks, and aftershocks and analyzed their statistical features such as the b-value of the frequency–magnitude distribution. We found that the b-values of the foreshocks are lower than those of the aftershocks. This b-value difference suggested that not only the stochastic cascade effect but also the stress changes/aseismic processes may contribute to the mainshock-triggering process. However, forecasting the mainshock based on b-value analysis may be difficult. In addition, the rate of foreshock occurrence in all clusters (with two or more events) was nearly constant (30–40%) over a wide magnitude range. The difference in the magnitude, time, and epicentral distance between the mainshock and largest foreshock followed a power law. We inferred that the distinctive characteristics of foreshocks can be better revealed using the improved catalog, which includes the micro-earthquake informatio