bluuebunny/crossref_metadata_2025_split huggingface dataset:
The structural design of the decay volume for the Search for Hidden Particles (SHIP) project
Authors: Miano Andrea , Fiorillo Antimo , Salzano Antonio , Prota Andrea , Jacobsson Richard 
Published: December 2020

Abstract
The Search for Hidden Particles (SHiP) experiment is a new general-purpose fixed target facility proposed at the CERN Super Proton Synchrotron (SPS) accelerator to search for long-lived exotic particles associated with Hidden Sectors and Dark Matter. This paper reports on the structural design of SHiP’s decay volume, a > 2000 m3 conical vessel under vacuum that should host several large particle physics detector systems. In the field of structural and seismic engineering, the design study in a very multidisciplinary international collaboration has represented a stimulating research challenge. The goal of the design of the decay is to produce a structure as light and as slim as possible to stay within the geometrical envelop determined in the physics simulations. A complete study has been performed with all the steps from the conceptual design, including the interaction with other components and the plant systems, to the assembly procedures for the decay volume realization. The complexity of the case study has been driven by the need of finding the appropriate compromise between the physics performance, the structural aspects, the executive, constructive and operational issues, and the economical constraints. The assembly strategy, the welding techniques, and the expected construction time are discussed in view of the extremely complex installation phase. Building Integrated Model (BIM) methodology is also proposed as an essential tool to coordinate the entire process of designing and managing not only the decay volume but the entire project.
Slip Tendency Analysis, Fault Reactivation Potential and Induced Seismicity in the Val d'Agri Oilfield (Italy)
Authors: Vadacca Luigi , Rossi Daniele , Scotti Anna , Buttinelli Mauro 
Published: December 2020

AbstractThe Val d'Agri basin hosts an oil‐field, the largest in onshore Europe, and it is one of the areas of highest seismic hazard in Italy. In an unproductive marginal portion of the reservoir, wastewater is re‐injected by a high‐rate well. Since the beginning of re‐injection in June 2006, a spatio‐temporal correlation between microseismicity (ML ≤ 2.0) and wastewater injection has been observed (suggesting induced seismicity). In this study, we perform a slip‐tendency analysis on the fault system involved in the induced seismicity through a coupled fluid‐flow and geomechanical numerical model simulating the stress partitioning due to the tectonic forces and to the fluid injection. The model results show that the fluid diffusion is strongly dependent on the active stress field and the geological structure in which fluids are injected, which conditioned the occurrence of seismicity that aligned on a small portion of a NE‐dipping fault. However, another fault located closer to the injection well and where no seismicity was detected, is the better well‐oriented fault with the active stress field and, also, the one more susceptible to the pore pressure increase. These results suggest different types of fault deformation acting in the Val d'Agri oilfield as response to the fluid injection (i.e., a mixed‐mode fault slip behavior). Understanding the stress partitioning in tectonically active regions where underground activities such as fluid injection are ongoing is fundamental to give strong constraints for the discrimination between natural and induced seismicity, and finally for a more reliable and robust definition of seismic hazard.
Influence of Subduction Zone Dynamics on Interface Shear Stress and Potential Relationship With Seismogenic Behavior
Authors: Beall Adam , Fagereng Åke , Davies J. Huw , Garel Fanny , Davies D. Rhodri 
Published: December 2020

AbstractWhether tectonic convergence at subduction zones is accommodated predominantly through seismic or aseismic deformation, the former potentially generating large earthquakes, varies considerably between subduction margins. This margin‐scale variability has previously been linked to overriding plate deformation, trench migration, and their influence on the plate interface stress state. While these processes are linked to mantle‐scale dynamics, it is unclear how such dynamics influence interface stress. We systematically analyze the interface stress state in a suite of 2‐D thermo‐mechanical subduction models, where slabs display a range of morphologies that arise from diverse multiscale interactions with adjacent mantle and the overriding plate. We demonstrate that the thickness of the interface layer varies dynamically, in response to Poiseuille flow induced by slab bending or unbending, leading to associated effects on interface shear stress at typical seismogenic depth. Lower shear stress occurs when slab unbending is significant, which is commonly associated with trench retreat and draping of the slab as it impinges on the higher‐viscosity lower‐mantle. Conversely, higher shear stress is associated with limited slab unbending, which is promoted by negligible trench migration and vertically subducting slabs. We conclude that the diversity of slab dynamics may cause large variations in interface stress state between and maybe within margins. This is an additional variable that potentially controls seismogenic behavior, and we compare broad stress estimates for Circum‐Pacific margins to previous studies. Although predicted shear stress varies with observed seismogenic behavior, more detailed constraints on stress state are needed to test for correlation.
Discovery of Alfvén Waves Planetward of Saturn's Rings
Authors: Southwood D. J. , Cao H. , Shebanits O. , Elsden T. , Hunt G. J. , Dougherty M. K. 
Published: December 2020

AbstractBetween April and September 2017 in the final stages of the Cassini Saturn Orbiter mission the spacecraft executed 22 orbits passing planetward of the innermost ring, the D‐ring. During all periapsis passes oscillations were detected in the azimuthal magnetic field components on typical time scales of a few minutes. We argue that these time‐varying magnetic signals detected on the spacecraft are also primarily time‐varying in the plasma frame. Furthermore, we show that nearly all signals exhibit a spatial feature, namely a magnetic node near the effective field line equator. We propose that the oscillations are associated with Alfvén waves excited in local field line resonances, most likely driven from global sources.
New Fault Slip Distribution for the 2010 Mw 7.2 El Mayor Cucapah Earthquake Based on Realistic 3D Finite Element Inversions of Coseismic Displacements Using Space Geodetic Data
Authors: Pulvirenti Fabio , Liu Zhen , Lundgren Paul , Gonzalez‐Ortega Alejandro , Aloisi Marco 
Published: December 2020

AbstractIn this work, we investigate the April 4, 2010, Mw 7.2 El Mayor Cucapah (EMC) earthquake. Existing studies modeled the EMC area as an elastic half‐space in a homogeneous or vertically layered structure, which, along with differences in data and inversion methodologies, led to considerable variability in the resultant fault slip models. To investigate the EMC earthquake more realistically, we first examine how published coseismic fault slip models have approached the problem and what are their findings, then we select the optimal geometry and slip of one most recent and comprehensive coseismic fault slip model, obtained through analytical inversions, and adapt them in a three‐dimensional finite element numerical environment where we assess the effects of topography and material heterogeneities. Numerically optimized slip models are obtained via joint inversion of GPS, interferometric synthetic aperture radar, and subpixel offset data sets. We find the effect of topography to be negligible while the inclusion of material heterogeneities enhances the slip at depth, as might be expected where the medium has higher rigidity, and better fits the displacements at both near and far field, especially around the Salton Sea area. The match with geodetic data is significantly improved when the fault slip is increased at the fault planes close to the epicenter and deeper at the southernmost plane, with respect to the slip of the chosen analytical model. Our findings suggest that this earthquake was associated with a higher and more spatially concentrated slip than previously thought implying a greater stress drop at depth.
Slip and Strain Accumulation Along the Sadie Creek Fault, Olympic Peninsula, Washington
Authors: Duckworth W. Cody , Amos Colin B. , Schermer Elizabeth R. , Loveless John P. , Rittenour Tammy M. 
Published: December 2020

AbstractUpper‐plate faulting in the Olympic Peninsula of Washington State results from relative motion of crustal blocks within the Cascadia forearc and earthquake cycle processes along the Cascadia subduction zone. We reconstruct fault slip rates since ∼14 ka on the Sadie Creek fault (SCF), north of the Olympic Mountains, using airborne lidar and field mapping of surficial deposits and landforms and optically stimulated luminescence and radiocarbon dating. The SCF is a ≥14 km‐long northwest‐striking, subvertical, dextral strike‐slip fault with a subordinate dip‐slip component. Laterally, offset debris flow channels cut into Late‐Pleistocene and younger surfaces show dextral slip of 4.0–24.5 m and dip slip of 0.7–6.5 m. Re‐evaluation of fault slip on the adjacent Lake Creek Boundary Creek fault (LCBCF) shows similar dextral (4.5–29.7 m) and dip slip (0.8–4.6 m). A deglacial age of 14 ka paired with the largest—and presumably oldest—slip measurements produce a minimum dextral slip rate of 1.3–2.3 mm/yr and dip‐slip rate of 0.05–0.5 mm/yr. Similarities in geometry, kinematics, slip rate, and earthquake timing between the SCF and LCBCF suggest these faults represent one continuous geologic structure, the North Olympic fault zone. Geodetically constrained boundary element method models considering the effects of coseismic subduction zone stresses on upper plate structures produce comparable kinematics to those measured on the SCF and LCBCF, suggesting that the North Olympic fault zone acts as the main strain‐accommodating structure in the northern Olympic Peninsula and may be modulated by stress transferred from subduction zone earthquakes.
Imaging the Crustal Interfaces Along the Ryukyu Arc‐Trough System Using Precursors to Teleseismic sP and pP
Authors: Jia Xinghua , Sun Daoyuan 
Published: December 2020

AbstractThe Ryukyu arc (RA)‐trough system, which is uniquely characterized by the Okinawa trough (OT) experiencing an early stage of continental disintegration, provides an ideal location to study continental rifting processes. However, the crustal structure beneath this region is not well resolved due to limited seismic surveys and station coverage. Here, by taking advantage of the well‐distributed intermediate‐depth earthquakes beneath the RA, we invert for the crustal structures beneath the RA‐trough system from the depth phases pP and sP and their precursors, underside reflected from the Moho and intracrustal interface. Along the RA, the Moho depth varies from 22 to 27 km indicating a thinner continental crust. Beneath the OT, the crustal thickness gradually decreases from 26 km to 15 km toward the south, which correlates with the trough rifting rates. At the south continental shelf, a thick crust with Moho depth of 29 km presents. In the transition region from the middle OT to the continental shelf, we observe multipathed precursors, which can be modeled with a 10 km Moho offset. The offset occurs in a gentle slope with angle of 27° dipping to the northwest, which supports a slow spreading process across the boundary between the middle OT and the continental shelf.
New Insights Into the Slip Budget at Nankai: An Iterative Approach to Estimate Coseismic Slip and Afterslip
Authors: Sherrill E. M. , Johnson K. M. 
Published: December 2020

AbstractThe slip budget at a subduction zone megathrust is met by a spectrum of slip behaviors including coseismic slip from great earthquakes, afterslip, episodic tremor and slip (ETS), long‐term slow slip events (SSEs), and quasisteady interseismic creep. Long‐term geodetic monitoring at the Nankai subduction zone in southwest Japan has recorded deformation observations spanning nearly a complete earthquake cycle, making this region the best study area for obtaining a full understanding of how the slip budget is partitioned along the interface and how the rheological conditions evolve through space and time. In this work, we conduct an iterative inversion of vertical surface displacement data to jointly estimate coseismic slip during the 1944/46 Tonankai and Nankai earthquakes, spatiotemporal afterslip history following those earthquakes, and postseismic mantle flow. A suite of postseismic models with variable elastic slab and plate geometry and mantle viscosity all show at least 30 years of sustained afterslip within the ETS zone and the gap between the top of the ETS zone and the fully coupled zone. This result demonstrates that stable, long‐duration afterslip is possible in the ETS zone. Summing the estimated cumulative slip from this study with estimates from previous studies of cumulative slip during the interseismic period, including episodic SSEs, we find that eastern Shikoku island has nearly met all of its slip budget for a 150‐year interseismic cycle, whereas western Shikoku island has a slip deficit of nearly half the budget (4 out of 8.25 meters) above 20 km depth on the subduction interface.
Rheology of Felsic Granulite at High Temperature and High Pressure
Authors: Wen D.‐P. , Wang Y.‐F. , Zhang J.‐F. , Li P.‐X. , Jin Z.‐M. 
Published: December 2020

AbstractRheological properties of continental lower crust (CLC) are essential for understanding many geodynamical processes in the Earth. Here we performed a series of deformation experiments on synthetic felsic granulite (65% plagioclase + 15% quartz + 9% clinopyroxene + 6% orthopyroxene + 5% amphibole) using a 5 GPa modified Griggs‐type deformation apparatus at 827–927°C and 1 GPa. All experiments have reached a steady‐state creep under conditions of constant pressure, temperature, and strain rate. Our data yield the following flow law:, whereis in s−1,σin MPa, andTin Kelvin. Microstructural observations show that plagioclase and pyroxene in deformed samples develop noticeable intracrystalline plasticity and shape preferred orientation (SPO). Electron backscatter diffraction (EBSD) measurements demonstrate more significant crystallographic preferred orientations (CPOs) of pyroxene and plagioclase in deformed granulites compared to those in hot‐pressed ones. By contrast, quartz develops nearly random fabrics probably due to the simultaneous activation of multiple slip systems during deformation. These features indicate that dislocation creep dominates the deformation of these minerals and felsic granulite, consistent with the obtained stress exponent. Our data imply that a CLC consisting of felsic granulite is weaker rheologically compared to the quartz‐dominated upper crust and the olivine‐dominated uppermost mantle, which supports the ‘jelly sandwich’ model for the strength of continental lithosphere. Additionally, extrapolations of flow laws of our felsic granulite and formerly‐reported mafic granulite strongly favor the hypothesis of delamination‐induced decratonization of the North China Craton.
Limited Mantle Hydration by Bending Faults at the Middle America Trench
Authors: Miller Nathaniel C. , Lizarralde Daniel , Collins John A. , Holbrook W. Steven , Van Avendonk Harm J. A. 
Published: December 2020

AbstractSeismic anisotropy measurements show that upper mantle hydration at the Middle America Trench (MAT) is limited to serpentinization and/or water in fault zones, rather than distributed uniformly. Subduction of hydrated oceanic lithosphere recycles water back into the deep mantle, drives arc volcanism, and affects seismicity at subduction zones. Constraining the extent of upper mantle hydration is an important part of understanding many fundamental processes on Earth. Substantially reduced seismic velocities in tomography suggest that outer rise plate‐bending faults provide a pathway for seawater to rehydrate the slab mantle just prior to subduction. Estimates of outer‐rise hydration based on tomograms vary significantly, with some large enough to imply that, globally, subduction has consumed more than two oceans worth of water during the Phanerozoic. We found that, while the mean upper mantle wavespeed is reduced at the MAT outer rise, the amplitude and orientation of inherited anisotropy are preserved at depths >1 km below the Moho. At shallower depths, relict anisotropy is replaced by slowing in the fault‐normal direction. These observations are incompatible with pervasive hydration but consistent with models of wave propagation through serpentinized fault zones that thin to <100‐m in width at depths >1 km below Moho. Confining hydration to fault zones reduces water storage estimates for the MAT upper mantle from ∼3.5 wt% to <0.9 wt% H20. Since the intermediate thermal structure in the ∼24 Myr‐old MAT slab favors serpentinization, limited hydration suggests that fault mechanics are the limiting factor, not temperatures. Subducting mantle may be similarly dry globally.
Eastward Dipping Style of the Underthrusting Indian Lithosphere Beneath the Tethyan Himalaya Illuminated by P and S Receiver Functions
Authors: Xu Qiang , Liu Hongbing , Yuan Xiaohui , Zhao Junmeng , Pei Shunping 
Published: December 2020

AbstractTo explore the west‐east variations in the underthrusting Indian lithosphere, we investigate the lithospheric structure using P and S receiver functions obtained from a west‐east linear array of 19 broadband stations spanning the Tethyan Himalaya at 85.5–88.5°E. Our observations of the Main Himalayan Thrust (MHT) and Moho serving as the top and bottom boundaries at depths of 42–54 km and 60–72 km, respectively, suggest that a thinning Indian lower crust with an eastward inclined geometry is underthrusting beneath the Tethyan Himalaya. An intra‐crustal low velocity zone (LVZ) immediately above the MTH at depths of 32–42 km is imaged, likely resulting from the presence of crustal dehydration partial melting. We propose that this LVZ induces the southward extrusion of melt‐weakened crustal material with itself as a channel and facilitates the development of duplexing structures, by which Indian lower crustal materials could be accreted into the Himalayan wedge along the north‐south mid‐crustal ramp in the MHT. The eastward dipping lithosphere‐asthenosphere boundary is clearly observed ranging from 90 to 126 km, which generally coincides with the changing trends of the MHT and Moho. These observations can be attributed to the eastward steepening subduction angle of the Indian lithosphere.
Complex Basal Conditions and Their Influence on Ice Flow at the Onset of the Northeast Greenland Ice Stream
Authors: Franke Steven , Jansen Daniela , Beyer Sebastian , Neckel Niklas , Binder Tobias , Paden John , Eisen Olaf 
Published: December 2020

AbstractThe ice stream geometry and large ice surface velocities at the onset region of the Northeast Greenland Ice Stream (NEGIS) are not yet well reproduced by ice sheet models. The quantification of basal sliding and a parametrization of basal conditions remains a major gap. In this study, we assess the basal conditions of the onset region of the NEGIS in a systematic analysis of airborne ultra‐wideband radar data. We evaluate basal roughness and basal return echoes in the context of the current ice stream geometry and ice surface velocity. We observe a change from a smooth to a rougher bed where the ice stream widens, and a distinct roughness anisotropy, indicating a preferred orientation of subglacial structures. In the upstream region, the excess ice mass flux through the shear margins is evacuated by ice flow acceleration and along‐flow stretching of the ice. At the downstream part, the generally rougher bed topography correlates with a decrease in flow acceleration and lateral variations in ice surface velocity. Together with basal water routing pathways, this hints to two different zones in this part of the NEGIS: the upstream region collecting water, with a reduced basal traction, and downstream, where the ice stream is slowing down and is widening on a rougher bed, with a distribution of basal water toward the shear margins. Our findings support the hypothesis that the NEGIS is strongly interconnected to the subglacial water system in its onset region, but also to the subglacial substrate and morphology.
Beyond Stationarity: Influence of Flow History and Sediment Supply on Coarse Bedload Transport
Authors: Downs P. W. , Soar P. J. 
Published: December 2020

AbstractUnderstanding how river bedload responds to climate and land use changes and water resource management initiatives is critical in developing sustainable approaches to river management. Passive monitoring techniques permit investigation of interannual dependencies in bedload transport in high resolution, including sediment supply factors. Here, seismic impact plate records are processed using a probabilistic model BedLoad from Impact Plates model to derive a 5‐year bedload data set at 5‐min intervals for the lower River Avon, Devon, UK. For water years that range from very dry to very wet, annual coarse bedload yields are estimated to vary through two orders of magnitude with wide prediction intervals. The most effective discharge occurs consistently at about one‐third of bankfull flow, morphologically at “subbarfull” stage, the result of hysteretic trends and falling limb transport in this non‐threshold channel. A two‐phase sediment rating curve is revealed with a variable supply related “bulge” during in‐bank flows, giving way to a near‐linear trend during overbank flows. The supply related component is predicted well using a sensitivity style metric that combines the cumulative duration of competent flows with the magnitude‐duration product of near‐threshold flows, defining a field‐scale exemplar of “stress history.” Further, the relative proportion of supply related coarse bedload yield relates strongly to the relative wetness of the previous year. High resolution, multiyear data reveal that controls on bedload dynamics are unique to a site's hydrogeoclimatic context and position in the river basin. Passive monitoring holds promise for generating “type sites” of bedload behavior critical for use in improving aquatic biodiversity and the sustainability of river management.
Fairness‐aware nonlinear joint transceiver design for energy‐harvesting‐powered CoMP systems
Authors: Hu Zhirui , Xu Fangmin , He Meilin , Lu Conghui , Zheng Changliang 
Published: December 2020

AbstractThis paper focuses on the fairness‐aware nonlinear joint transceiver design for the energy‐harvesting (EH)‐powered coordinated multi‐point (CoMP) systems. In the EH‐powered CoMP systems, each node harvests the energy independently first. Then, these nodes collaborate for joint signal transmission. Since there is no conventional grid to connect the nodes, the energy among nodes cannot be coordinated. Therefore, per‐node power constraints should be satisfied, which however has not been considered in existing schemes. In this paper, a fairness‐aware nonlinear transceiver scheme is developed under the per‐node power constraints. The nonlinear transceiver design is formulated as an optimization problem to maximize the minimum signal‐to‐interference noise ratio of data streams. A two‐step optimization algorithm is proposed to obtain the closed‐form solutions in the cases with perfect channel state information (CSI) and imperfect CSI, respectively. Simulation results verify the fairness of the proposed algorithm, and demonstrate its performance enhancement in sum‐rate and bit ratio error (BER). For sum‐rate, the proposed algorithm can achieve 12% gain over WS‐MSE and 40% gain over BD at SNR = 20 dB. For BER, it can achieve an approximately 4 dB gain over WS‐MSE and 8 dB gain over BD at BER = 10−3.