Steep Structures Research Articles

Fermi Rubik’s Cube in High-pressure Induced Chlorine-riched Compounds

Abstract In the quasi-free electron model, which is widely used in modern solid-state physics, the Fermi surface spreads into a sphere in the Brillouin zone, i.e., the Fermi Sphere. The Fermi Sphere exists widely in metal systems, no matter whether the crystal is in a body-center cubic, face-center cubic, or hexagonal close-packed lattice. Here, we report a class of compounds stabilized at high pressure with a Rubik's cubic Fermi surface, in which the representative example is P m-3n-CaCl3. Our quantum-mechanical variable- composition evolutionary simulations predicted the thermal stabilities of CaCl3, and the tight-binding model revealed its unique Fermi surface originates from the quasi-one- dimensional interaction, structural symmetric protection, and particle-hole symmetry breaking. Furthermore, by its flat and steep band structure, CaCl3 has a huge span of effective mass from 9.08×103 me (super-heavy) to 5.13×10-4 me on the Fermi level, which supplies an interesting platform for quasiparticle research.

Steep Slope Field Effect Transistors Based on 2D Materials

AbstractWith field effect transistor (FET) sustained to downscale to sub‐10 nm nodes, performance degradation originates from short channel effects (SCEs) degradation and power consumption increment attributed to inhibition of supply voltage (VDD) scaling down proportionally caused by thermionic limit subthreshold swing (SS) (60 mV dec−1) pose substantial challenges for today's semiconductor industry. To further sustain the Moore's law life, incorporation of new device concepts or new materials are imperative. 2D materials are predicted to be able to combat SCEs by virtue of high carrier mobility maintainability regardless of thickness thinning down, dangling bonds free surface and atomic thickness, which contributes to super gate electrostatic controllability. To overcome increasing power dissipation problem, new device structures including negative capacitance FET (NCFET), tunnel FET (TFET), dirac source FET (DSFET) and the like, which show superiority in decreasing VDD by lowering SS below thermionic limit of 60 mV dec−1 have been brought out. The combination of 2D materials and ultralow steep slope device structures holds great promise for low power‐dissipation electronics, which encompass both suppressed SCEs and reduced VDD simultaneously, leading to improved device performance and lowered power dissipation.

Wave Impacts On Cliffs: From The Field To The Laboratory

Rock coasts occupy over 50% of the global shoreline and many sandy beaches are underlain by coastal platforms and rocky cliffs. The problem of wave-driven cliff erosion is of great societal importance, with many coastal communities located on top of cliffs that are at risk from erosion. Continuing global mean sea level rise and changes in storminess are generally expected to exacerbate the erosion of coastlines (Hurst et al., 2016), as larger waves can reach the cliff toe without breaking offshore. However, the science underpinning wave-induced cliff erosion is still at a relatively early stage. Even the relative contributions of waves to cliff erosion, which include hydraulic forces, impulse pressures and abrasion, are not well resolved. Most insights into wave impacts on cliffs come from field observations of coastal ground motion during storm events (e.g. Young et al., 2011, Huppert et al., 2020). These field investigations demonstrate the dependence of large wave impacts on both water levels and wave conditions, and in some cases the correlation of periods of large ground motion with increased erosion (Earlie et al., 2015). Unsurprisingly, although large impacts generally occur at high tide during storms characterised by large significant wave heights, the largest impacts occur when tidal levels and storm surge combine to provide water levels that are conducive to the incident waves breaking on the cliffs (Thompson et al., 2019; 2022). Larger wave heights or shallower water levels tend to lead to breaking further offshore, with a broken wave interacting with the cliff, while smaller wave heights or deeper water levels may preclude strong wave breaking on the cliffs. There have been relatively few experimental studies into wave-driven cliff erosion; these were generally undertaken under very idealised wave conditions (e.g. Sunamura, 1977) and using materials that were either too soft to approximate natural rocks (e.g. Sunamura, 1977; 1982) or too hard to be eroded (Hansom et al., 2008). Although these experiments have informed the development of rocky coast evolution models, their results have not been replicated or verified, and rigorous scaling laws to link laboratory erosion rates to field time scales are currently lacking. However, considering cliffs as steep or vertical (natural) coastal structures, a large body of experimental work has been undertaken to investigate impact pressures and their implications for the failure of engineered structures (e.g. Peregrine, 2003, Bullock et al., 2007). These investigations are complicated by the inherent variability of the wave impact pressures, even within controlled experiments undertaken with highly repeatable incident wave conditions (Raby et al., 2022). Although field and laboratory data are valuable, it is still very challenging to quantify wave contributions to cliff erosion due to the relatively short durations and variable conditions of most field records. On the other hand, most controlled laboratory investigations have typically focused on loads on non-erodible engineered structures such as seawalls. The current project seeks to advance understanding of the fundamental mechanisms and timescales of wave-driven erosion on rocky cliffs, which will be vital in improving assessments of cliff erosion hazard in high-energy wave environments as sea levels rise.

High-order residual moveout correction with global optimization in local time windows

Residual moveout (RMO) correction is significant for optimizing the common image gathers (CIGs) and migration stacked sections, which is a vital step in seismic data processing. The conventional RMO correction methods flatten the migrated gathers by inverse normal moveout and then pick up the velocity parameters, which require high labor of manual picking with low efficiency. The existing high-order RMO correction methods by scanning technology need a bispectral picking process. To address these issues, we propose a novel high-order RMO correction method based on a crosscorrelation-based objective function with global optimization in local time windows. The selected time windows covering the reflected events in the stacked section are used for parameter estimation. Then the very fast simulated annealing (VFSA) algorithm is used to simultaneously invert the two effective parameters (migration velocity and anellipticity anisotropic parameter) with the local CIGs in the time window, which has relatively high computational efficiency. The Hess model example test results show that the proposed method can effectively deal with the RMO problem in the case of anisotropic media, and the developed high-order RMO correction based on anisotropic assumption significantly improved the imaging performance compared to the conventional isotropic RMO correction methods, especially for steep structures. The application to a real 3D land data set further confirms the effectiveness and practicability of the proposed method.

Fluid-Induced Metamorphism and Deformation at the Eastern Boundary of the Sveconorwegian Province

Abstract The Sveconorwegian orogen in Scandinavia and the Grenville orogen in Canada are both remnants of large and hot orogens that formed part of the supercontinent Rodinia around 1 billion years ago. Formerly deeply buried portions of crust in these orogens are exposed and offer insights into the tectonic dynamics of the basement within large orogens. The Eastern Segment of the Sveconorwegian Province hosts a ~ 30 000 km2 crustal portion that was buried to c. 40 km depth at a late stage of the orogeny, 980–960 Ma ago, and is bound towards the foreland in the east by a ~ 25 km wide zone of step anastomosing deformation, the Frontal wedge. This zone represents the outermost ductile deformation that developed within the crystalline basement in the orogen. We investigated a heterogeneously deformed and recrystallised syenodiorite with the aim to understand the character of the deformation-related metamorphism within the Frontal wedge. Field relations, microtextures, and mineral reactions show that the metamorphic recrystallisation was governed by hydrous fluid infiltration along the ductile deformation zones. Equilibrium was attained on a millimetre scale only and metamorphic recrystallisation was dependent on the introduction of hydrous fluid. The metamorphism reached high-pressure epidote-amphibolite-facies; geothermobarometric estimates suggest 540°C to 600°C and 9 to 12 kbar. Metamorphic zircon formed during the breakdown of Zr-bearing igneous phases, primarily baddeleyite. SIMS U–Pb analyses of igneous zircon and baddeleyite date the igneous crystallisation of the syenodiorite at 1230 ± 6 Ma. Metamorphic zircon grains are <20 μm and too small for precise dating, but yielded ages around 1 Ga. Collectively, the metamorphic data indicate that subvertical movements along steep planes within the Frontal wedge allowed for the regional-scale tectonic burial to ~40 km depth of the Eastern Segment to the west. Some of the same steep deformation structures were re-utilised as discrete movement planes during later exhumation.

Ascent and emplacement controls of mafic magmas in the mid crust − evidence from 3D modelling of basic bodies of the Koperberg Suite, Namaqualand

Abstract The 3D modelling of basic bodies of the Koperberg Suite (1060 to 1030 Ma) and their wall rocks from Narrap Mine illustrates the distribution, geometries and, by implication, processes that determined the ascent and emplacement of the mantle-derived mafic magmas into the partially-molten, mid-crustal granite-gneiss sequence of the Okiep Copper District in Namaqualand. The lens-like, discontinuous geometry of basic bodies suggests the transfer of the mafic magmas as self-contained, buoyancy-driven hydrofractures. The presence of both shallowly-dipping, foliation-parallel sills and subvertical lenses in zones of steep foliation development, so-called steep structures, indicates an emplacement of the mafic magmas under low deviatoric stresses and irrespective of the regional stress field. Instead, the emplacement of the mafic magmas parallel to pre-existing anisotropies (tectonic fabrics or lithological contacts) highlights those differences in tensile strength and fracture toughness parallel to or across anisotropies determined the propagation of the magmas. This also accounts for the common occurrence of basic bodies in steep structures in which the vertical gneissosity promoted the buoyancy-driven ascent of the mafic magmas. On a regional scale, the mechanical stratification of the subhorizontal, sheet-like granite gneisses and interlayered metasediments exerted important controls on the ascent of Koperberg Suite magmas. The preferential emplacement of basic bodies in schist and gneiss units suggests that the lower rigidity of the ductile wall rocks facilitated magma emplacement through a combination of viscous wall-rock deformation and fracture blunting that led to the arrest of the magma-filled hydrofractures. Multiple intrusive relationships of successively emplaced magma batches suggest that later magmas reutilised earlier established magma pathways, particularly in steep structures. High-rigidity lithologies, such as the massive Springbok Quartzite, in contrast, only allowed for smaller fracture apertures and limited dilation, resulting in the pinching of basic bodies and rather stringer-like geometries. It is conceivable that the higher fracture toughness of the quartzite may also have prevented propagation of the mafic magmas through the Springbok Quartzite and, instead, led to the ponding of basic bodies below the metasediments. The geometry and structural and lithological controls of basic bodies at Narrap Mine are similar to Koperberg Suite intrusions documented from many of the other mine workings in the Okiep Copper District. This suggests similar underlying emplacement controls of the cupriferous rocks, which can be extrapolated on a regional scale and that may guide exploration.

NUMERICAL STUDY ON THE INTERACTION BETWEEN PERIODIC WAVES AND A FLEXIBLE WALL

Coastal structures were usually considered as stiff in the majority of studies related to wave structure interaction I n certain situations, such as impulsive wave loading on flexible breakwaters, ship hulls, tank walls hydroelasticity can be of importance for both wave dynamics and structural responses Akrish et al. (2018) showed that hydroelastic effects can either relax or amplify the hydrodynamic characteristics (i.e., wave run up and force) and structural oscillations in a deformable cantilever wal l interacting with an incident wave group. For flexible coastal defenses, Huang and Li (2022) showed that an elastic horizontal plate breakwater can exhibit a better performance of wave damping than a rigid one. Sree et al. (2021) experimentally investigated a submerged horizontal viscoelastic plate under surface waves. They reported a complete cutoff of the wave energy with the flexible plate. However, the hydroelasticity of a steep fronted structure in nonlinear progressive waves was not yet studied in a de tailed manner , which requires advanced numerical methods for modelling the nonlinear interaction between the fluid and the solid with finite deformations. The present study focus es on the hydroelastic behavior of a flexible vertical wall in nonlinear periodic waves with different wave periods (or frequencies )). The effects of the structural stiffness on the wave evolution and the structural deformation are investigated with a fully coupled wave structure interaction model.

Modeling of thin-film interference filters on structured substrates: microfacet-based BSDF versus ray tracing.

We compare two model approaches for the ray optical description of PV modules with coloring based on an interference layer system on the inside of the cover glass. The light scattering is described by a microfacet-based bidirectional scattering distribution function (BSDF) model on the one hand and ray tracing on the other hand. We show that the microfacet-based BSDF model is largely sufficient for the structures used in the context of the MorphoColor application. A structure inversion shows a significant influence only for extreme angles and very steep structures showing correlated heights and surface normal orientations. Regarding an angle-independent color appearance, the model-based comparison of possible module configurations shows a clear advantage of a structured layer system compared to planar interference layers in combination with a scattering structure on the front side of the glass.

Convolutional Neural-Network-Based Reverse-Time Migration with Multiple Reflections.

Reverse-time migration (RTM) has the advantage that it can handle steep dipping structures and offer high-resolution images of the complex subsurface. Nevertheless, there are some limitations to the chosen initial model, aperture illumination and computation efficiency. RTM has a strong dependency on the initial velocity model. The RTM result image will perform poorly if the input background velocity model is inaccurate. One solution is to apply least-squares reverse-time migration (LSRTM), which updates the reflectivity and suppresses artifacts through iterations. However, the output resolution still depends heavily on the input and accuracy of the velocity model, even more than for standard RTM. For the aperture limitation, RTM with multiple reflections (RTMM) is instrumental in improving the illumination but will generate crosstalks because of the interference between different orders of multiples. We proposed a method based on a convolutional neural network (CNN) that behaves like a filter applying the inverse of the Hessian. This approach can learn patterns representing the relation between the reflectivity obtained through RTMM and the true reflectivity obtained from velocity models through a residual U-Net with an identity mapping. Once trained, this neural network can be used to enhance the quality of RTMM images. Numerical experiments show that RTMM-CNN can recover major structures and thin layers with higher resolution and improved accuracy compared with the RTM-CNN method. Additionally, the proposed method demonstrates a significant degree of generalizability across diverse geology models, encompassing complex thin layers, salt bodies, folds, and faults. Moreover, The computational efficiency of the method is demonstrated by its lower computational cost compared with LSRTM.

Snow Avalanche Risk Assessment using GIS-Based AHP for Bitlis Province

Bitlis province, located in the Eastern Anatolia of Turkey, is the region with the highest snowfall in the country. Due to its highland and steep structure, the region is under high avalanche risk. Assessment of the snow avalanche risks is important in terms of modern disaster management. In this study, the avalanche risks were assessed by using the analytical hierarchy process (AHP), which is an effective multiple criteria decision-making methods. The avalanche risk was considered depend on many factors such as temperature, slope, elevation, aspect, land use, soil, lithology, precipitation, distance to fault and population. The outputs obtained from the method were mapped in the GIS environment and thus the avalanche risks of the region were determined. According to the results, especially the highland and steep southern parts and the two volcanic mountain foothills in the region were evaluated as high risk. The study results were validated by comparing past avalanche events and some previous researches.

Geological Controls on Marine Cavernous Landforms along Japanese Pacific-side Rocky Coasts

Marine cavernous landforms, including notches, caves, arches and tunnels, characterize the rocky coast landscape and are strongly influenced by the geology (e.g., rock strength and structure) of sea cliffs. Geological controls on the development and shape of marine cavernous landforms are evaluated based on field investigations along the Pacific coastlines of Honshu Island, Japan. Morphological parameters, width (w), depth (d), and height (h), of cavernous landforms were measured directly or through images taken with an unmanned aerial vehicle, together with geological factors, such as rock types, strength (Schmidt hammer rebound values: R), dips and strikes of bedding, major joints, and fault planes. In total, 76 caves are investigated in six coastal areas: Sanriku Coast, Joban Coast, Boso Peninsula, Miura Peninsula, Izu Peninsula, and Kii Peninsula. According to shape index, d/w, and presence of the open end, cavernous landforms are classified into notches (d/w < 1, closed end), caves (d/w ≥ 1, closed end), arches (d/w < 1, open end), and tunnels (d/w ≥ 1, open end). An analysis shows that the major geological controls differ between notches and the other three forms. Low rock strength (R < 40) and sub-horizontal bedding are, respectively, the primary and secondary controls on the formation of notches, whereas weak rock structures (joints, faults and bedding) with a dip steeper than 30° (vertical or steeply inclined structures) and a strike trending perpendicular to the cliff face are the major controls on the formation of caves, arches and tunnels. Rock strength also affects planar forms defined by the shape index, promoting a deepening of cavernous forms, particularly when the cliff has a medium rock strength (R = 30-50) that provides an optimal balance between erosion force and resisting force. In general, vertical or steep structures contribute to the deepening of holes, whereas horizontal or gentle structures favor widening.

Least-Squares Full-Wavefield Reverse Time Migration Using a Modeling Engine With Vector Reflectivity

Conventional least-squares reverse time migration (LSRTM) generally involves a de-migration operator based on the first-order scattering approximation (Born modeling), which can only simulate the seismograms containing the primary reflected wave. When the input observed seismograms contain “redundant information” (especially multiples), crosstalk may occur in the imaging results. Therefore, we develop a least-squares full-wavefield reverse time migration (LSFWM), which is implemented based on a two-way modeling engine with vector reflectivity and the corresponding adjoint sensitive kernel. This modeling engine is modified from the variable density acoustic wave equation and can simulate the subsurface wavefield containing the primaries and multiples only by giving the accurate or estimated subsurface reflectivity and velocity. Theoretically, this LSFWM approach can eliminate the influence of “redundant information” on imaging and provide higher-quality imaging results compared to conventional LSRTM. In addition, since the modeling engine is based on vector reflectivity, the imaging results produced by the LSFWM are also vectorized, which can give more information about the subsurface structures, especially steep structures. And the imaging results produced by the LSFWM can accurately depict the subsurface reflectivity. These are helpful to obtain the information on subsurface structure and physical properties more clearly.

Enhancing one-way wave equation-based migration with deep learning

One advantage of one-way wave equation-based migration is its low computational cost. However, due to the limited wavefield propagation angle, it is difficult to use one-way wave equation-based migration for high-precision imaging of structures with large inclinations due to issues such as inaccurate amplitudes and migration image artifacts. In addition, when the model has large horizontal velocity differences, it is difficult for the one-way wave propagator to calculate an accurate wavefield phase. Reverse time migration (RTM) based on the two-way wave propagator has a high resolution and avoids the issues associated with one-way wave propagators; however, it has a high computational cost in practical applications. We develop a convolutional neural network (CNN) application mode that improves one migration method by learning from another one and design a CNN with a structure similar to U-net that combines the advantages of both migration methods. The CNN label is the RTM result, and the corresponding input is the result of one-way wave migration with a generalized screen propagator (GSP). The trained CNN model improves the amplitude in the one-way wave migration image and removes the errors caused by large lateral velocity perturbations. Moreover, by maintaining the high migration calculation efficiency, our CNN model allows for a high resolution, few artifacts, and accurate images of steep structures in the one-way wave migration result. With our method, the accuracy of the one-way wave migration result is close to that of the RTM result. The use of GSP-based migration in our CNN model rather than conventional RTM to generate prospecting images can considerably reduce the calculation costs.

Widespread subsonic turbulence in Ophiuchus North 1

Context. Supersonic motions are common in molecular clouds. (Sub)sonic turbulence is usually detected toward dense cores and filaments. However, it remains unknown whether (sub)sonic motions at larger scales (≳1 pc) may be present in various environments. Aims. Located at a distance of about 110 pc, Ophiuchus North 1 (Oph N1) is one of the nearest molecular clouds that would allow for an in-depth investigation of its turbulence properties via large-scale mapping observations of single-dish telescopes. Methods. We carried out the 12CO (J = 1−0) and C18O (J = 1−0) imaging observations toward Oph N1 with the Purple Mountain Observatory 13.7 m telescope. The observations have an angular resolution of ~55″ (i.e., 0.03 pc). Results. Most of the whole C18O emitting regions have Mach numbers of ≲1, demonstrating the large-scale (sub)sonic turbulence across Oph N1. Based on the polarization measurements, we estimate the magnetic field strength of the plane-of-sky component to be ≳9 µG. We infer that Oph N1 is globally sub-Alfvénic, and is supported against gravity mainly by the magnetic field. The steep velocity structure function can be caused by the expansion of the Sh 2–27 HII region or the dissipative range of incompressible turbulence. Conclusions. Our observations reveal a surprising case of clouds that are characterized by widespread subsonic turbulence and a steep relation between the size and the linewidth. This cloud is magnetized where ion-neutral friction is assumed to play an important role.

Volume imaging of aspect sensitivity in VHF radar backscatters: first results inferred from the Advanced Indian MST radar (AIR)

ABSTRACT Very-high frequency (VHF) radar echoes are known to be aspect sensitive in general, which could be either the manifestation of a thin stable layer providing sharp refractive index gradient or shear-driven steep layer structures. The present study for the first time shows the volume imaging of aspect sensitivity in the recently upgraded Advanced Indian Mesosphere Stratosphere Troposphere (MST) radar (AIR). The present configuration of radar can provide a better understanding of three-dimensional structures of turbulence and instabilities, which was not possible when the radar was operated in two orthogonal planes. Both isotropic and anisotropic layers/turbulence are observed at various height levels over the radar volume. Enhanced aspect sensitivity is observed between 6 and 9 km, which is attributed to the presence of dynamic instability arising due to strong wind shear and atmospheric stability. All the scatterers tend to become isotropic when both the square of wind shear and stability parameters are above 0.25 × 10−3 s−2. Due to the high aspect sensitivity, there may be an underestimate of 5–10% in wind velocity measurements, and it is higher for the low off-zenith beam angle.

Improvement of blue response of black Si solar cells due to graded band structure

We have investigated characteristics of energy band structure of a nanocrystalline Si (nc-Si) layer produced by the surface structure chemical transfer (SSCT) method, especially its effects on quantum efficiency of crystalline Si solar cells. In the nc-Si layer, the size of Si nanocrystals decreases toward the surface because Si dissolves nonuniformly from the surface during the SSCT reaction. The valence band maximum of the outermost surface of the nc-Si layer is located at 0.1–0.3 eV lower than that of Si bulk, and the conduction band minimum increases by 0.17–0.25 eV toward the surface. These results indicate that the nc-Si layer has a graded band structure in which the band-gap energy gradually increases toward the surface. By optimizing the SSCT reaction conditions, thinner thickness (∼100 nm) of the nc-Si layer and smaller size of Si nanocrystals can be obtained, resulting in a steep graded band structure. Because of reduction of carrier recombination rate in the surface region by the steep graded band structure, a high internal quantum efficiency over 80% in the 300–400 nm wavelength region is obtained.

Elastic least-squares reverse time migration of steeply dipping structures using prismatic reflections

The migration of prismatic reflections can be used to delineate steeply dipping structures, which is crucial for oil and gas exploration and production. Elastic least-squares reverse time migration (ELSRTM), which considers the effects of elastic wave propagation, can be used to obtain reasonable subsurface reflectivity estimations and interpret multicomponent seismic data. In most cases, we can only obtain a smooth migration model. Thus, conventional ELSRTM, which is based on the first-order Born approximation, considers only primary reflections and cannot resolve steeply dipping structures. To address this issue, we develop an ELSRTM framework, called Pris-ELSRTM, which can jointly image primary and prismatic reflections in multicomponent seismic data. When Pris-ELSRTM is directly applied to multicomponent records, near-vertical structures can be resolved. However, the application of imaging conditions established for prismatic reflections to primary reflections destabilizes the process and leads to severe contamination of the results. Therefore, we further improve the Pris-ELSRTM framework by separating prismatic reflections from recorded multicomponent data. By removing artificial imaging conditions from the normal equation, primary and prismatic reflections can be imaged based on unique imaging conditions. The results of synthetic tests and field data applications demonstrate that the improved Pris-ELSRTM framework produces high-quality images of steeply dipping P- and S-wave velocity structures. However, it is difficult to delineate steep density structures because of the insensitivity of the density to prismatic reflections.

Formation Pressure Inversion Method Based on Multisource Information

SummaryThe exploration and development of offshore oil and gas have greatly alleviated the tension of global oil and gas resources. However, the abnormal pressure of offshore reservoirs is more common compared with terrestrial oil and gas reservoirs, and the marine geological structure is complex, with the development of faults, fractures, and high and steep structures, which leads to the strong anisotropy of formation pore pressure distribution and uncertainty of pressure system change. In this paper, considering the corresponding characteristics of the randomness of the formation pressure prediction results in the Eaton equation for their respective variables, a formation pressure inversion method based on multisource information, such as predrilling data, bottomhole while drilling data, seabed measured data, and surface measured data, is established. On this basis, combined with the data of a well in the South China Sea, the variation law of the uncertainty of formation pressure prediction results under the conditions of predrilling data, measurement while drilling (MWD) data, and their mutual coupling is analyzed. The simulation results show that the uncertainty distribution of formation pressure prediction based solely on predrilling data shows linear accumulation trend with well depth, and the formation pressure inversion method based on multisource information can significantly curb the increasing trend of uncertainty when MWD data are introduced. Therefore, through the analysis of typical change patterns of monitoring parameters under normal/abnormal conditions during drilling, combined with the method of multisource information, the abnormal pressure information can be accurately predicted and inversed, which provides important support for wellbore pressure regulation under complex formation conditions.

Socio-hydrological modeling and its issues in Japan: a case study in Naganuma District, Nagano City

The Asian monsoon and Japan’s steep terrain structure make it a flood-prone country. These natural, flood-prone features have prompted Japan to develop unique social norms for flood risk management. Over the last decade, human-flood interaction models have been developed in socio-hydrology (SH), being applied and validated in various countries. This study applied the SH model for the Naganuma District of Nagano City, Japan, an area that was affected by Typhoon Hagibis in 2019. Additionally, the SH model was examined for its applicability in Japan using sensitivity analysis. To the best of our knowledge, this is the first study to apply the SH model in a real-life scenario in Japan. The results suggest that there are differences between the output from the existing SH model and the actual human-flood interactions in Japanese society. This paper also provides recommendations to improve the Japanese SH model and inform associated future research agendas in Japan.

Sheeted intrusion of granitic magmas in the upper crust – Emplacement and thermal evolution of the Guandacolinos pluton, NW Argentina

The Lower Carboniferous Guandacolinos pluton of northwestern Argentina (Western Sierras Pampeanas) preserves field, structural, and petrological evidence of sheet-like transport and assembly of granitic magmas in the upper crust. The pluton is a relatively small (~24 km2) subduction-related granitic body, elongated in map view, and hosted in Neoproterozoic metamorphic rocks. Exceptional exposure records a subparallel array of steep NNE-SSW trending structures, including steep contacts partly concordant with host rock structure, numerous sheets of granite separated by host rock rafts, abundant xenoliths, and magmatic and solid-state foliations. Along the eastern half of the pluton, the granite is massive and host rock inclusions are less abundant. Regional markers of the host rock are deflected along a concordant bulged contact in the northeastern region of the pluton. Field relations indicate emplacement by multiple material transfer processes including fracture propagation, magma wedging, stoping, and lateral shortening. Contrasting mechanisms imply a changing mechanical response of host rock and multiple stages of intrusion. Emplacement began with dominant brittle fracturing and intrusion of sheets influenced by host rock anisotropies, followed by a viscoelastic phase were larger batches of magma caused downward transfer of stoped blocks, lateral expansion, and minor ductile deformation of the host rock. Thermal modelling indicates that the construction of the pluton required lateral accretion rates in the order of dm/years and less than a few tens of thousands of years to form. This case study documents the ability of incrementally assembled sheeted intrusions to efficiently heat rocks of the upper crust and trigger conditions favourable for transfer and storage of magma.