Volume Of Debris Research Articles

Numerical and experimental study on effects of net-bullet ejection angles and initial distances on space-debris capture

The increasing volume of space debris in the outer space poses a significant threat to operational spacecraft. Hence, net capture systems have emerged as a promising technique for removing space debris. These systems operate by deploying a net to envelop and capture the debris. The effectiveness of debris capture using nets depends on ejection parameters such as speed, ejection angle, and the crucial initial distance between the net and debris. Simulations are performed to examine various scenarios of active debris removal. In addition, the experiments involved meticulously calibrated net and debris ejector systems, where bullets are utilized for net deployment by varying the angle of bullet ejection (θ). The net trajectory is determined using simplified equations of motion, while considering both the ejection dynamics and its interaction with the debris. The findings of this study reveal the correlations between the initial parameters and net performance pertaining to space debris capture. Larger ejection angles and greater distances between the net and the debris-hindered debris capture. Despite slight simultaneous net and debris ejection delays, the results of the real-world experiments validated the simulation results.

Trem2-deficiency aggravates and accelerates age-related myelin degeneration

Aging is the greatest known risk factor for most neurodegenerative diseases. Myelin degeneration is an early pathological indicator of these diseases and a normal part of aging; albeit, to a lesser extent. Despite this, little is known about the contribution of age-related myelin degeneration on neurodegenerative disease. Microglia participate in modulating white matter events from demyelination to remyelination, including regulation of (de)myelination by the microglial innate immune receptor triggering receptor expressed on myeloid cells 2 (TREM2). Here, we demonstrate Trem2-deficiency aggravates and accelerates age-related myelin degeneration in the striatum. We show TREM2 is necessary for remyelination by recruiting reparative glia and mediating signaling that promotes OPC differentiation/maturation. In response to demyelination, TREM2 is required for phagocytosis of large volumes of myelin debris. In addition to lysosomal regulation, we show TREM2 can modify the ER stress response, even prior to overt myelin debris, that prevents lipid accumulation and microglial dysfunction. These data support a role for Trem2-dependent interactions in age-related myelin degeneration and suggest a basis for how early dysfunctional microglia could contribute to disease pathology through insufficent repair, defective phagocytosis, and the ER stress response.

Evaluation of apically extruded debris during root canal filling material removal in teeth with external apical root resorption: a comparison of different obturation techniques

BackgroundRoot canal retreatment is necessary when initial treatment fails. Nickel-titanium systems help remove filling materials; however, some methods can cause canal content extrusion, resulting in inflammation and delayed healing. This study aimed to examine the impact of different preparation techniques and endodontic file systems on apical debris volume to limit material dispersion to periradicular tissues.MethodsNinety extracted maxillary incisors were evaluated. Simulated apical root resorption was created by removing the apical 2 mm of the root. The teeth were divided into two groups: one filled with a single cone and the other with cold lateral compaction (CLC). Each group was further divided into three subgroups (n = 15 each): Subgroup 1 used Reciproc R25 for removal and R50 for final preparation; Subgroup 2 used ProTaper Universal Retreatment (PTUR) files D1, D2, and D3 for removal and ProTaper Next X5 for finalization; and Subgroup 3 used VDW.Rotate Retreatment (VDW.RotateR) for removal and VDW.Rotate 50.04 for completion. Debris from retreatment was collected in pre-weighed tubes to determine the amount. The apical extrusion data underwent a two-way analysis of variance.ResultsThe Reciproc group had a mean extruded debris weight of 0.54 ± 0.24 mg, higher than the PTUR (0.28 ± 0.15 mg) and VDW.RotateR (0.39 ± 0.29 mg) groups (p < 0.05). The single-cone technique (SCT) resulted in a mean debris weight of 0.34 ± 0.23 mg, lower than the CLC technique, which had a mean of 0.46 ± 0.27 mg (p < 0.05). SCT had a shorter retreatment duration (111.12 ± 33.46 s) compared to CLC (176.26 ± 52.26 s) (p < 0.05).ConclusionThe Reciproc file system and the CLC obturation technique resulted in greater apical debris extrusion than the other methods. SCT was quicker than CLC. The Reciproc groups are more susceptible to apex extrusion during retreatment.

A post-hurricane building debris estimation workflow enabled by uncertainty-aware AI and crowdsourcing

Climate disasters often result in large amounts of debris that need to be cleaned up in the event's aftermath. Effective post-disaster debris management poses unique challenges due to limited resources, high expenses, and the nonhomogeneous and hazardous debris content. Current practices of debris cleanup rely on time-consuming and error-prone field-based estimation, which impedes immediate response and accurate analysis. While new approaches such as artificial intelligence (AI) and crowdsourcing have shown promise in various domains, their potential for debris estimation remains underexplored. This study leverages a human-AI teaming workflow that estimates post-disaster debris volume and composition. The workflow begins with the utilization of drones to capture aerial views for efficient disaster infrastructure reconnaissance. Subsequently, an AI model and a crowdsourcing module are calibrated and work together to rapidly and reliably detect damaged buildings and classify the levels of damage based on aerial imagery. By establishing a connection between building damage states and the resulting generated debris, these damage level predictions serve as a foundation for the efficient and accurate estimation of debris. Overall, the proposed approach uses drones for rapid data collection and AI to automate damage detection and classification, which reduces the time required for debris estimation from days to a few hours as well as minimizes predictive uncertainty with crowdsourcing by up to 40%. A case study on Hurricane Laura in 2020 was conducted to validate the proposed approach. Findings of this study lead to predicting debris volume and composition with minimal errors, particularly for partially damaged buildings.

A novel electric field-assisted material extrusion process for clean additive manufacturing

Material extrusion (MEX) is a type of additive manufacturing technique that is widely used in a variety of applications. However, the issue of reduced quality of printed parts caused by degraded polymer debris accumulation on the nozzle surface during the MEX process has received very limited attention. This work presents a novel electric field-assisted MEX (E-MEX) method to solve the quality issue by significantly reducing the accumulations of polymer debris on the nozzle. By applying a high-voltage power source between the nozzle and the build plate, an electrostatic force was generated to overcome the which showed great potential to reduce the accumulation of molten thermoplastic material on the nozzles. Both the E-MEX and conventional MEX methods were used to print test specimens for specific amounts of time to confirm the efficacy of the E-MEX method. 3D scanning was used to quantify the volumes of debris that had accumulated on the nozzle. Compared to the conventional MEX method, the E-MEX printing reduced debris accumulation by 47 % after about 5 h and over 80 % after about 15 h of the printing process. The changes in electric field intensity over orienting height were analyzed using numerical simulations. The relationship between electric field intensity and time spent by the nozzle during the printing process at a specific height was established. The polymer accumulation in the E-MEX process was found to be dependent on the electric field intensity and the continuous time spent by the nozzle in the weaker electric field enhanced polymer debris accumulations on the nozzle surfaces. The presented study integrates experimental observations with simulation results, revealing the mechanism of debris accumulation on the nozzle when the electric field decreased to a certain level during printing process. A numerical simulation model was developed to understand the traveling of accumulated polymer debris from the nozzle's outer surface to the printing layer under the influence of electrostatic force. The simulation results showed that the dragging of polymer debris towards the build plate occurs when the electric force acting in the tangential and normal direction is sufficient to overcome the viscous force and normal force in the polymer debris. The simulation results also showed some part of the debris remained in the crease area of the nozzle surface due to the viscous and surface tension forces prevailing over the electric force.

Seasonal shifts in the habitat selection patterns of male American Marten (Martes americana) at a fine spatial scale.

Old-growth forests harbor a large amount of complex structural features that result in a wide array of wildlife habitats. However, intensive forest management is gradually converting old-growth forest into younger, even-aged stands, reducing structural complexity and threatening the persistence of old-growth-dependent species. Maintaining elements of complex stand structure is critical to the conservation of old-growth forest specialists that use different habitat components at different periods of their annual cycle, and it requires a comprehensive understanding of seasonal variation in the habitat needs of these species. However, difficulties in observing free-ranging animals have sometimes limited our ability to assess such variations in habitat requirements, especially for small, elusive species. To address this, we used GPS telemetry collars to describe fine-scale habitat selection patterns of 6 male American Martens (Martes americana) during 2 contrasting periods of the year (snow-free, from mid-April to mid-November; snow-covered, from mid-November to mid-April), an objective formerly hard to achieve using conventional VHF telemetry. We used resource selection functions conducted at the fourth order of selection to compare habitat characteristics found at the sites used by martens (GPS locations, n = 100) to those found on an equal number of available sites (random points, n = 100) within each individual seasonal home range. We conducted vegetation surveys on these 200 sites to describe habitat and built candidate models representing different concurrent hypotheses. Our results showed that proxies of prey availability, predator avoidance, and thermal constraints were the primary factors influencing marten habitat selection during both periods, although their respective importance differed between periods. Martens selected sites with a high density of large-diameter snags (≥30·ha-1), high conifer canopy closure (≥53%), and a dense lateral cover (≥81%) during the snow-free period, but selected sites with a high volume of coarse woody debris (≥64 m3·ha-1) and high conifer canopy closure (≥48%) during the snow-covered period. Our results highlight the importance of contrasting seasonal changes in habitat selection patterns of small carnivores and may help maintain structural attributes in the landscape that are suitable for male American Martens.

Patterns of deadwood amount and deadwood diversity along a natural forest recovery gradient from agriculture to old-growth lowland tropical forests

AbstractDeadwood is a key component of nutrient cycling in natural tropical forests, serving as a globally important carbon storage and habitat for a high number of species. The conversion of tropical forests to agriculture modifies deadwood pools, but we know little about deadwood dynamics in forests recovering from human disturbance. Here we quantified the volume and diversity of coarse woody debris (CWD, ≥ 7 cm diameter) and the mass of fine woody debris (FWD, &lt; 7 cm) along a chronosequence of natural forest recovery in the lowlands of the Ecuadorian Chocó region. We sampled forest plots ranging from 1–37 years of recovery post-cessation of agricultural use as either cacao plantation or cattle pasture, as well as actively managed cacao plantations and cattle pastures, and old-growth forests. In contrast to our expectation, we found no significant increase in deadwood volume with recovery time. The diversity in size, decay stage and type of CWD increased along the recovery gradient, with no effect of previous land use type. The mass of FWD increased overall across the recovery gradient, but these results were driven by a steep increase in former pastures, with no change observed in former cacao plantations. We suggest that the range of sizes and decomposition stages of deadwood found in these two major tropical agricultural systems could provide suitable resources for saproxylic organisms and an overlooked carbon storage outside old-growth forests. Our estimates of deadwood in agricultural systems and recovering forests can help improve global assessments of carbon storage and release in the tropics.

Spatial Analyses for Fine Woody Debris Volume Stock in the Hyrcanian Research Forest of Kheyrood-Kenar

Spatial Analyses for Fine Woody Debris Volume Stock in the Hyrcanian Research Forest of Kheyrood-Kenar

A framework to enhance disaster debris estimation with AI and aerial photogrammetry

This study addresses the critical need to enhance disaster preparedness and response, focusing on hurricane impact assessment and debris estimation. Accurate assessments in this context are critical for post-event search-and-rescue (SAR) operations and resource distribution. Recent computing advancements are revealing the potential of unmanned aerial vehicles (UAVs) and artificial intelligence (AI) technologies in collecting data and assisting with post-hurricane reconnaissance. However, the use of AI and UAV photogrammetry for accurate disaster impact analysis remains underexplored. To this end, this study proposes a damage and debris analysis framework harnessing reality capture through aerial imagery and photogrammetry. Within this framework, a region-based neural network is leveraged to detect debris locations in aerial imagery with favorable performance. In a testbed within the Beaumont-Port Arthur region, in Southeast Texas, this study performs 3D reality captures of the built environment. Since the accuracy of the 3D reality capture is of importance in research areas associated with time-sensitive disaster response, we further investigate the optimal 2D aerial imagery overlap ratio required to generate a sufficiently accurate 3D model for disaster impact analysis and debris volume estimation. Results indicate that, in the case of aerial imagery for infrastructure systems, a minimum of 60 % overlap is recommended for damage assessment and debris analysis. In contrast, for flat green areas, a minimum of 50 % overlap is adequate. Overall, for disaster response applications, our study reveals that an overlap ratio between 60 % and 70 % is optimal for achieving a balance between time efficiency and data quality in aerial data collection. These quantitative recommendations are crucial for enabling efficient disaster response efforts. Additionally, our study outcomes will improve disaster impact analysis and facilitating timely and effective response strategies.

Application and comparison of remote sensing techniques for data-driven disaster debris quantification

ABSTRACT Effective disaster debris management requires reasonable predictions pre-hazard and estimates post-hazard of debris for a community to get back to normal sooner. However, there is a lack of data related to post-disaster waste quantities that could validate and improve debris predictions. This knowledge gap can be addressed by using remote sensing technology to quantify disaster debris promptly following a hazard. This study aimed to demonstrate and compare multiple remote sensing tools available for quantifying disaster debris using post-disaster data collected following Hurricane Ida. The tools used in this study are satellite imagery, emergency response airborne imagery, unmanned aerial vehicles (UAVs), and terrestrial laser scanning (TLS). We found that satellite imagery is useful for quantifying vegetative debris generation and transportation across vast areas, however it is often limited by spatial and temporal resolutions. Emergency response airborne imagery, collected within days following the hazard, is well-suited for quantifying transported vegetative debris and can assist debris clearance of emergency service routes across large areas, although it can be limited spatially and temporally to the interests of the acquiring agency. UAVs and TLS can provide precise volumes of debris but UAVs may be a better option due to their lower cost and computational demand. Guidance is provided for selecting a remote sensing tool based on the desired application and available resources, which can assist decision making for disaster waste managers.

Is the Tupul (Makhuam) Landslide of 29-30 June 2022 in Manipur, India Recognized as one of the Rainfall Induced Massive Landslide?

The present study deals with Tupul landslide in Manipur which triggered on the intervening night of 29th -30th June 2022 in Noney district of Manipur. The death toll was 61 persons in total from Territorial Army, NF Railway’s employees, Villagers and labours from various contractors in the construction of railway line from Jiribam to Imphal. We have conducted a drone survey on the landslide site for preparation of large-scale terrain map and compared 2009 CARTOSAT image to pick up the slip surfaces. The detailed fieldwork of the study area deciphers highly jointed, fractured, faulted rock formations and display neo-tectonic movements. The slope failure analysis was conducted using the Phase-2 software and the failure was compared with the Drone made DEM, which is used to estimate the volume of debris falling on the railway formations. The excessive precipitation (375.6mm) during the May 2022 was recorded near the landslide site which was 60% more than the normal precipitation. In order to maintain the safety of the man and materials for the future, a number of suggestions were proposed for future monitoring of slope along coming up railway lines of Northeast Frontier Railways.

+Fretting wear: A phenomological approach

An analytical description of fretting wear is proposed wherein the volume of wear debris either removed from the sliding interface or retained within these areas, is represented as a fraction of the freshly-produced debris in each fretting pass. In the proposed model, the volumes respectively of removed debris and of retained debris are tallied over each pass of a fretting sequence to yield a closed analytical expression relating these volumes to the number of passes. The paper provides an example of the adaptation of the proposed model to experimental wear data on steel-steel fretting interfaces.

Post-harvest regeneration is driven by ecological factors rather than wood procurement intensity in eastern Canadian forests

Abstract Biomass from surplus forest growth that is not harvested for wood supply of conventional industries can be an important source of feedstock for bioenergy. Its procurement can be integrated with little effort into current harvest operations. However, the increasing harvesting intensity to meet greater demand for biomass procurement can impact forest ecosystem functions because of its direct and indirect effects on woody debris and the regeneration of next-rotation stands. In this context, we aimed to determine the relationships between wood procurement intensity, woody debris inputs, and regeneration success over 2 years after harvesting. We tested four treatments of increasing wood procurement intensity using a randomized block design within six experimental sites along a gradient of varying forest characteristics of boreal and temperate forests. We assessed stand characteristics in terms of standing trees, woody debris, and regeneration pre- and post-harvest. We used mixed effects models to evaluate (i) the effects of wood procurement intensity and pre-harvest stand characteristics on the volume and cover of woody debris and (ii) the specific influence of woody debris on the presence of suitable planting microsites post-harvest. Furthermore, we used principal component regressions to explore the relationships between harvesting intensity and the presence of natural regeneration and competing vegetation as a function of pre- and post-harvest stand characteristics (iii). Our results showed that increasing wood procurement intensity reduced the volume of post-harvest woody debris while having a limited effect on regeneration. Increasing harvesting intensity had a negligible effect on suitable planting microsites in hardwood-dominated stands but it increased their presence in conifer-dominated stands. Natural regeneration and competing vegetation were mainly related to stand characteristics, and only broadleaf regeneration was sensitive to harvest intensity. We conclude that the relationships between wood procurement intensity and regeneration are complex and rely mainly on stand characteristics rather than wood procurement needs.

FOREST FEATURE LIDAR SLAM (F2-LSLAM) AND INTEGRATED SCAN SIMULTANEOUS TRAJECTORY ENHANCEMENT AND MAPPING (IS2-TEAM) FOR ACCURATE FOREST INVENTORY USING BACKPACK SYSTEMS

Abstract. Under-canopy mapping is desired to derive critical forest biometrics, such as diameter at breast height (DBH), merchantable height, and debris volume. The main challenge of such under-canopy mapping is the intermittent access to the global navigation satellite system (GNSS) signal, which is crucial to deriving accurately georeferenced mapping products. In this study, we propose two frameworks – Forest Feature LiDAR Simultaneous Localization and Mapping (F2-LSLAM) and Integrated Scan Simultaneous Trajectory Enhancement and mapping (IS2-TEAM) – for 3D LiDAR unit mounted on backpack systems to achieve accurate forest inventory. In the F2-LSLAM strategy, ground/tree trunk features are extracted from individual LiDAR scans. On the other hand, when trajectory information provided by navigation sensors is available, these semantic features are derived from LiDAR points within several scans (i.e., integrated scan) for the IS2-TEAM strategy. Then, local/global least squares adjustment (LSA) using derived features is performed to register LiDAR scans to a common reference frame for both strategies. To evaluate the performance of the proposed strategies, three in-house developed backpack systems with varying specifications were used to collect data in complicated forest environments. Through the comparison with point clouds acquired by a commercial backpack LiDAR system, the proposed frameworks are capable of generating point clouds with satisfactory intra-dataset alignment quality (in the range of 2–4 cm) for all backpack systems in natural forest areas with relatively flat terrain. However, for more challenging areas with dense undergrowth vegetation and/or large height differences, F2-LSLAM framework cannot extract sufficient features, while IS2-TEAM still exhibits good performance.

Vitamin E effects on the wear resistance of UHMWPE sheets against an EBM-produced Ti6Al4V pin

The present article shows preliminary findings on the impact of adding vitamin E to polyethylene. Specimens of ultra-high-molecular-weight polyethylene UHMWPE, both pure and modified with vitamin E, were produced and tested by a pin-on-disc apparatus. The specimens were analyzed using techniques such as differential scanning calorimetry, Shore-D tests, optical microscopy, and surface profile measurements. To replicate the actual wear conditions in prosthetic joints, a pin made of Ti6Al4V, produced using electron beam melting, was used. The wear test results demonstrated that lubrication with simulated synovial fluid reduces debris volume. Furthermore, the addition of vitamin E to the polymer further reduced debris production.

Long-term changes in coarse woody debris abundance in three Appalachian headwater streams with differing best management practices

IntroductionTimber harvests influence coarse woody debris (CWD) dynamics both initially and long-term—contributing a significant amount of CWD as slash immediately after harvest, but also removing some or all of the mature trees necessary to produce CWD over time. Whereas shelterwood and other similar timber harvest systems retain varying amounts of the overstory, preserving CWD production after harvest, commercial clearcutting essentially eliminates sources of fresh CWD until regenerating trees are large enough to contribute CWD through fallen limbs or trunks, often decades after harvest. Forestry best management practices (BMPs) are critical for reducing the water quality impacts of timber harvest, but their effects on riparian and stream CWD are not well understood.MethodsThe current project explores CWD dynamics (surveyed in 2001, 2004, 2009, and 2020) in three eastern Kentucky watersheds receiving differing timber harvest treatments in 1983: unharvested control, BMPs (clearcut with a protected streamside management zone), and no BMPs (clearcut).ResultsAnalysis of hydrology data over the period of record demonstrated significant flooding in 2004 that likely “reset” CWD in the study watersheds. Coarse woody debris volume was higher in control (3.33 m3/ha) than no BMP (1.03 m3/ha) in 2020, with CWD accumulation rates ranging from 0.039 m3/ha in the no BMP watershed to 0.19 m3/ha in the control.DiscussionWhile not significantly different, CWD volume was nominally higher in the BMP watershed than the No BMP watershed, suggesting that, in addition to their many other benefits, streamside management zones help facilitate CWD provisioning during stand initiation after a commercial clearcut harvest. Furthermore, this study suggests that provisioning of CWD may not recover after clearcut harvesting for 100 years or more.

Optimal Leg Height of Landing Legs to Reduce Risk of ‎Damage from Regolith Ejecta by Retrorocket Exhausts

Over the past decade, there has been a rapid increase in rocket launches. 2022 was a record-breaking year for the ‎aerospace ‎industry, with 180 successful rocket launches into orbit, 44 more than the previous year. Reducing as ‎many risks as possible is ‎essential as interplanetary rocket launches and reusable booster landings become more ‎frequent. One such risk occurs when a ‎rocket/booster lands. During the landing process, the retrorockets spray debris ‎from the loose ground, which may damage the ‎rocket/landing module. Retrorockets are rocket engines that provide ‎a thrust opposing the spacecraft’s motion, causing it to ‎decelerate. This paper studies the effect of landing leg height ‎on ejecta velocity, the volume of debris ejected, and ground ‎surface temperature change. Four landing leg heights ‎were tested with an Estes® E-16 consumer model rocket motor: 0 mm, ‎‎50 mm, 75 mm, and 100 mm. The ‎experiment suggests that the optimal height above the ground’s surface for a simulated ‎landing module based on ‎the volume and velocity of the ejecta is 50 mm. Landing legs that elevate a model rocket this height ‎create an ‎average crater volume of 610.5 mL and a max crater diameter of 10.34 cm. After determining the optimal height, a ‎‎landing leg system was developed. This system was attached to an Aerodactyl TS® model rocket and utilized ‎landing legs that ‎elevated the rocket to a height of 50 mm above the ground at landing.‎‎

To flat or not to flat? Exploring the impact of flat-side design on rotary instruments using a comprehensive multimethod investigation.

To assess the influence of a flat-side design on the geometry, metallurgy, mechanical performance and shaping ability of a novel nickel-titanium rotary instrument. Sixty-five new 25-mm flat-side rotary instruments (size 25, taper 0.04) and their nonflat-side prototypes (n = 65) were assessed for major deformations and examined regarding macroscopic and microscopic design, determination of nickel and titanium elements ratio, measurement of phase transformation temperature and evaluation of mechanical performance parameters including time/cycles to fracture, maximum torque, angle of rotation, maximum bending and buckling strengths and cutting ability. Additionally, unprepared canal areas, volume of hard tissue debris and percentage reduction of dentine thickness were calculated for each tested instrument after preparing mesial canals of mandibular molars (n = 12), using micro-CT imaging. Statistical analyses were performed using the U-Mann-Whitney test and independent Student t-test (α = 5%). The number of spirals (n = 8) and blade direction (clockwise) were similar between both flat and nonflat instruments, whilst the helical angles were equivalent (⁓25°). Flat-instruments showed inconsistencies in the homogeneity of the gold colour on the flat-side surface, blade discontinuity, and incomplete and variable S-shaped cross-sections. The titanium-to-nickel ratios were equivalent, but significant differences in the R-phase finish and austenitic start phase transformation temperatures were observed between the flat and nonflat-side instruments. The flat-side instruments demonstrated superior cutting ability compared to the nonflat instruments, as well as, significantly lower values for time to fracture, rotation to fracture and maximum torque to fracture (p < .001). No statistical difference was observed between tested instruments regarding angle of rotation (p = .437), maximum bending (p = .152) and buckling load (p = .411). Preparation protocols using flat and nonflat instruments did not show any statistically significant differences (p > .05). All flat-side instruments exhibited deformation after shaping procedures. The flat-side instrument showcased enhanced cutting ability compared to its nonflat counterpart. However, it exhibited inferior performance in terms of time, rotation and maximum torque to fracture, along with distinct phase transformation temperatures. No differences were observed in the titanium-to-nickel ratios, angle of rotation, maximum bending, buckling load, preparation time, percentage of untouched canal walls, volume of hard tissue debris and percentage reduction of dentine thickness.

3D Simulation of Debris Flows with the Coupled Eulerian–Lagrangian Method and an Investigation of the Runout

In landslide risk management, it is important to estimate the run-out distance of landslides (or debris flows) such that the consequences can be estimated. This research presents an innovative array of dimensionless equations that effectively estimate run-out distances, supported by both experimental data and numerical simulations. We employ the coupled Eulerian–Lagrangian (CEL) method to confront the challenges presented in large deformations during landslides. The soil is modelled using the Mohr–Coulomb model, and the failure of cohesionless soil slopes (e.g., sand slopes) is studied. The simulation results are used to study the characteristics of flows and run-out distances. We suggest a normalized run-out and introduce new scaling relationships for it under different conditions such as different plane angles and material properties. The granular flows under different scales can be compared directly with this new scaling law. The new relationships are validated by both experimental and numerical data. Our analysis reveals that the normalized run-out distance in debris flows is contingent on the initial geometry, plane angle, and material properties. An increase in debris volume and plane angle can contribute to an increase in the normalized run-out distance, while a rise in friction angles causes a decrease. In the case of landslides, the normalized run-out distance depends on material properties and the slope angle. An increase in slope angle leads to a corresponding increase in the normalized run-out distance.

Earthquake contributions to coastal cliff retreat

Abstract. Modeling suggests that steep coastal regions will experience increasingly rapid erosion related to climate-change-induced sea level rise. Earthquakes can also cause intense episodes of coastal cliff retreat, but coseismic failures are rarely captured in the historical record used to calibrate most cliff retreat forecast models. Here, we disaggregate cliff-top retreat related to strong ground motion and non-seismic sources, providing a unique window into earthquake contributions to multidecadal coastal cliff retreat. Widespread landsliding and up to ca. 19 m of coastal cliff-top retreat occurred in the area of Conway Flat during the 2016 Kaikōura (New Zealand) earthquake despite relatively low (ca. 0.2 g) peak ground accelerations. While coastal cliff-top retreat has been spatially and temporally variable over the historical record, aerial imagery suggests that large earthquake-induced landslide-triggering events disproportionately contribute to an average 0.25 m yr−1 retreat at Conway Flat. The 2016 Kaikōura earthquake represents ca. 24 % of the total cliff-top retreat over 72 years and ca. 39 % of cliff-top retreat over 56 years. Additionally, we infer that significant retreat between 1950 and 1966 is the result of local seismicity. Together these two events account for ca. 57 % of cliff-top retreat over 72 years. Earthquake-related debris piles at the base of the cliffs have been rapidly eroded since the 2016 Kaikōura earthquake (more than 25 % loss of debris volume in 5 years), and there will likely be little evidence of the earthquake within the next decade. In regions with similar lithologic and coastal conditions, evidence of past widespread single-event cliff-top retreat may be limited or non-existent. The results demonstrate that cliff-top retreat projections using historical records may significantly underestimate true retreat rates in seismically active regions.