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Abstract: The westernmost Nankai Trough, southwest Japan, exhibits a rapid along-strike reduction in plate coupling in the proximity to the subducting Kyushu-Palau ridge. Yet how and to what extent the ridge subduction impacts physical properties at the megathrust have not been investigated. Here we present high-resolution seismic P-wave velocity models along the forearc wedge in the western Nankai Trough derived from full-waveform inversion analyses of seismic refraction data. The velocity models show that where the plate coupling is weak and the plate boundary presumably hosts slow earthquakes, the upper plate exhibits lower seismic velocities indicating higher degree of fracturing over a ~ 100 km length along trough. Intriguingly, the extent of the upper-plate low-velocity features is significantly larger than the surficial width of the Kyushu-Palau ridge, and this low-velocity zone is underthrust by the slab with increased crustal thickness by 2–4 km. Seismic reflection images consistently reveal that the thicker slab crust has appreciable basement roughness extending ~ 60 km from the eastern margin of the Kyushu-Palau ridge beneath the western Shikoku basin. We suggest that such a thicker and rugged slab crust, together with the main body of the Kyushu-Palau ridge, can cause significant fracture zones in the overriding plate, decrease the interplate coupling and produce preferable conditions for shallow slow earthquakes to occur when subducted. The results may also provide structural constraints on the western limit of future megathrust earthquakes in the Nankai Trough. Graphical Abstract

In shallow subduction zones, fluid behavior impacts various geodynamic processes capable of regulating slip behaviors and forming mud volcanoes. However, evidence of structures that control the fluid transfer within an overriding plate is limited and the physical properties at the source faults of slow earthquakes are poorly understood. Here we present high-resolution seismic velocity models and reflection images of the Hyuga-nada area, Japan, where the Kyushu-Palau ridge subducts. We image distinct kilometer-wide columns in the upper plate with reduced velocities that extend vertically from the seafloor down to 10-13 km depth. We interpret the low-velocity columns as damaged zones caused by seamount subduction and suggest that they serve as conduits, facilitating vertical fluid migration from the plate boundary. The lateral variation in upper-plate velocity and seismic reflectivity along the plate boundary correlates with the distribution of slow earthquakes, indicating that the upper-plate drainage system controls the complex pattern of seismic slip at subduction faults.

Background/Objectives Individual eating habits may be influenced by genetic factors, in addition to environmental factors. Previous studies suggested that adherence to Japanese food patterns was associated with a decreased risk of all-cause and cardiovascular disease mortality. We conducted a genome-wide association study (GWAS) in a Japanese population to find genetic variations that affect adherence to a Japanese food pattern. Subjects/Methods We analyzed GWAS data using 14,079 participants from the Japan Multi-Institutional Collaborative Cohort study. We made a Japanese food score based on six food groups. Association of the imputed variants with the Japanese food score was performed by linear regression analysis with adjustments for age, sex, total energy intake, alcohol intake (g/day), and principal components 1-10 omitting variants in the major histocompatibility region. Results We found one SNP in the 14q11.2 locus that was significantly associated with the Japanese food score with P values Conclusion We found a new SNP that was associated with the Japanese food score in a Japanese population. This SNP is inversely associated with genes link to olfaction and obesity., Author(s): Harumitsu Suzuki [sup.1] [sup.2] , Yasuyuki Nakamura [sup.3] [sup.4] , Keitaro Matsuo [sup.5] [sup.6] , Nahomi Imaeda [sup.7] [sup.8] , Chiho Goto [sup.8] [sup.9] , Akira Narita [sup.10] , [...]

Background/objective Although benefits of fish consumption for health are well known, a significant percentage of individuals dislike eating fish. Fish consumption may be influenced by genetic factors in addition to environmental factors. We conducted a genome-wide association study (GWAS) to find genetic variations that affect fish consumption in a Japanese population. Methods We performed a two-stage GWAS on fish consumption using 13,739 discovery samples from the Japan Multi-Institutional Collaborative Cohort study, and 2845 replication samples from the other population. We used a semi-quantitative food frequency questionnaire to estimate food intake. Association of the imputed variants with fish consumption was analyzed by separate linear regression models per variant, with adjustments for age, sex, energy intake, principal component analysis components 1-10, and alcohol intake (g/day). We also performed conditional analysis. Results We found 27 single nucleotide polymorphisms (SNPs) located in 12q24 and 14q32.12 that were associated with fish consumption. The 19 SNPs were located at 11 genes including six lead SNPs at the BRAP, ACAD10, ALDH2, NAA25, and HECTD4 regions on 12q24.12-13, and CCDC197 region on 14q32.12. In replication samples, all five SNPs located on chromosome 12 were replicated successfully, but the one on chromosome 14 was not. Conditional analyses revealed that the five lead variants in chromosome 12 were in fact the same signal. Conclusion We found that new SNPs in the 12q24 locus were related to fish intake in two Japanese populations. The associations between SNPs on chromosome 12 and fish intake were strongly confounded by drinking status., Author(s): Taro Suzuki [sup.1] , Yasuyuki Nakamura [sup.2] [sup.3] , Keitaro Matsuo [sup.4] , Isao Oze [sup.4] , Yukio Doi [sup.1] , Akira Narita [sup.5] , Atsushi Shimizu [sup.6] , [...]

Accurate earthquake source parameters are crucial for understanding plate tectonics, yet, it is difficult to determine these parameters precisely for offshore events, especially for outer‐rise earthquakes, as the limited availability of direct P or S wave data sets from land‐based seismic networks and the unsuitability of simplified 1D methods for the complex 3D structures of subducting systems. To overcome these challenges, we employ an efficient hybrid numerical simulation method to model these 3D structural effects on teleseismic P/SH and P‐coda waves and determine the reliable centroid locations and focal mechanisms of outer‐rise normal‐faulting earthquakes in northeastern Japan. Two M6+ events with reliable locations from ocean bottom seismic observations are utilized to calibrate the 3D velocity structure. Our findings indicate that 3D synthetic waveforms are sensitive to both event location, thanks to bathymetry and water reverberation effects, and the shallow portion of the lithospheric structure. With our preferred velocity model, which has Versus ∼16% lower than the global average, event locations are determined with uncertainties of <5 km for horizontal position and <1 km for depth. The refined event locations in a good match between one of the nodal strikes and the high‐resolution bathymetry, enabling the determination of the causative fault plane. Our results reveal that trench‐ward dipping normal faults are more active, with three parallel to the trench as expected, while five are associated with the abyssal hills. The significant velocity reduction in the uppermost lithosphere suggests abundant water migrating through active normal faults, enhancing both mineral alteration and pore density. Plain Language Summary: The subduction of oceanic plates plays a crucial role in recycling earth materials and generating the largest earthquakes and tsunamis. This process causes significant bending of the oceanic plate near the trench, where forces from frictional coupling on the plate interface and far‐field subduction loading act in opposite directions, forming a gentle bulge on the seafloor termed the outer‐rise region. This region is rich in shallow bending‐related earthquakes at shallow depths and is characterized by rough bathymetry bounded by faults. Identifying the relationship between these earthquakes and their hosting faults is critical for understanding the seismic and tsunami hazards and fault development in the outer rise. However, building up this link is impeded by large uncertainties of earthquake source parameters. Here, we employ an advanced numerical wavefield simulation approach to precisely handle the structural complexity near 8 ∼ M6 outer‐rise earthquakes, which allows use of far‐field seismic waveform data to constrain source parameters. Reliable earthquake locations and focal mechanisms, along with high‐resolution bathymetry, enable us to identify the causative faults. Dramatically low velocity structure of the subducting oceanic plate is also revealed through this process, which suggests a fluid‐rich outer rise region that efficiently recycles water into the deeper earth. Key Points: Centroid location and focal mechanism of outer‐rise earthquakes were reliably determined through 3D modeling of teleseismic body wavesAlong with high‐resolution bathymetry, reliable source parameters allow us to identify the ruptured faults hosting these normal events3D waveform modeling required a Versus ∼16% lower than the global average, suggesting a fluid‐rich oceanic lithosphere at the outer rise [ABSTRACT FROM AUTHOR]

Passerini polymerization using naturally occurring α-lipoic acid as a raw material yields polyamides with 1,2-dithiolane functional groups in a one-step reaction. The polyamide exhibits characteristics of an adaptable dynamically crosslinked network through reversible ring-opening reaction of 1,2-dithiolane, enabling self-healing, reusable strong adhesion, and regeneration through decrosslinking and re-crosslinking. [ABSTRACT FROM AUTHOR]

Sixty genetic loci associated with abdominal obesity, measured by waist circumference (WC) and waist-hip ratio (WHR), have been previously identified, primarily from studies conducted in European-ancestry populations. We conducted a meta-analysis of associations of abdominal obesity with approximately 2.5 million single nucleotide polymorphisms (SNPs) among 53,052 (for WC) and 48,312 (for WHR) individuals of Asian descent, and replicated 33 selected SNPs among 3,762 to 17,110 additional individuals. We identified four novel loci near the EFEMP1, ADAMTSL3 , CNPY2, and GNAS genes that were associated with WC after adjustment for body mass index (BMI); two loci near the NID2 and HLA-DRB5 genes associated with WHR after adjustment for BMI, and three loci near the CEP120, TSC22D2, and SLC22A2 genes associated with WC without adjustment for BMI. Functional enrichment analyses revealed enrichment of corticotropin-releasing hormone signaling, GNRH signaling, and/or CDK5 signaling pathways for those newly-identified loci. Our study provides additional insight on genetic contribution to abdominal obesity.

We examined the possible factors affecting the spatial distribution of very low frequency earthquakes and tremors in the shallow megathrust of Nankai Trough (<30 km) using a dense network of prestack depth migrated profiles at the frontal wedge. Geometrical parameters examined were decollement roughness, taper angle, and underthrust thickness. Physical properties such as effective basal friction (μb) and pore pressure ratio (λ*) were calculated from the taper angle and p‐wave velocity. Regions of low λ* (0.39 ± 0.08) and smooth decollement showed no slow earthquake activity. In contrast, high activity of slow earthquakes was observed in areas with a rough decollement due to the presence of subducted seamounts or bathymetric highs. The low taper angle (3.8°) off Muroto where slow earthquakes also occur translates to a wide zone of low μb (0.21 ± 0.06) and high λ* (0.66 ± 0.06). However, our results also show that slow earthquakes don't always occur in areas with high λ*. Plain Language Summary: Slow earthquakes such as very low frequency earthquakes and tremors are different than typical earthquakes because they occur longer and can last for more than several days. They have been reported in numerous subduction zones around the world and the study of slow earthquakes has recently gained attention because they have been suggested as precursors to larger earthquakes albeit on rare occasions. Slow earthquakes show a clustered distribution in the Nankai Trough. We used a dense network of seismic reflection data acquired at the shallow portion of the Nankai Trough to examine why some areas have high activity and some areas have no activity. Our results showed that areas with no slow earthquake activity have a smooth decollement and low pore fluid pressure. On the other hand, areas with high slow earthquake activity have a rough decollement. The occurrence of slow earthquakes has been typically associated with high pore fluid pressure because it allows the two slabs of rock to slide easier. However, our results suggest that high pore fluid pressure may not always be a prerequisite for slow earthquakes to occur. Key Points: A smooth decollement due to absence of subducted seamounts or bathymetric highs, and low pore fluid pressure results in a slow earthquake gapSlow earthquakes don't always occur in areas of high pore pressure but in combination with other variables like decollement roughnessThe low taper angle off Muroto indicates a wide zone of low friction and high pore pressure possibly associated with subducted seamounts [ABSTRACT FROM AUTHOR]