Search Results (188)

The South Shetland Islands and Antarctic Peninsula (SHETPENANT region) constitute a geodynamically active area shaped by the interaction of major tectonic plates and active magmatic systems. This study analyzes GNSS time series spanning from 2017 to 2024 to investigate surface deformation associated with the 2020–2021 seismic swarm near the Orca submarine volcano. Horizontal and vertical displacement velocities were estimated for the preseismic, coseismic, and postseismic phases using the CATS method. Results reveal significant coseismic displacements exceeding 20 mm in the horizontal components near Orca, associated with rapid magmatic pressure release and dike intrusion. Postseismic velocities indicate continued, though slower, deformation attributed to crustal relaxation. Stations located near the Orca exhibit nonlinear, transient behavior, whereas more distant stations display stable, linear trends, highlighting the spatial heterogeneity of crustal deformation. Stress and strain fields derived from the velocity models identify zones of extensional dilatation in the central Bransfield Basin and localized compression near magmatic intrusions. Maximum strain rates during the coseismic phase exceeded 200 $\mathrm{\nu }$strain/year, supporting a scenario of crustal thinning and fault reactivation. These patterns align with the known structural framework of the region. The integration of GNSS-based displacement and strain modeling proves essential for resolving active volcano-tectonic interactions. The findings enhance our understanding of back-arc deformation processes in polar regions and support the development of more effective geohazard monitoring strategies. Full article

The Dehbid region, located in the southern part of the Sanandaj–Sirjan Zone (SSZ), is a significant iron oxide mining district with over 20 iron oxide deposits (IODs) and reserves of up to 50 million tons of iron oxide ores. The region features a NW–SE oriented ductile shear zone, parallel to the Zagros thrust zone, experienced significant deformation. Detailed structural studies indicate that the iron mineralization is primarily stratiform to stratabound and hosted in late Triassic to early Jurassic silicified dolomites and schists. These ore deposits consist of lenticular iron oxide orebodies and exhibit various structures and textures, including banded, laminated, folded, disseminated, and massive forms of magnetite and hematite. The Fe₂O₃ content in the mineralized layers varies from 30 to 91 wt%, whereas MnO has an average of 3.9 wt%. The trace elements are generally low, except for elevated concentrations of Cu (up to 4350 ppm) and Zn (up to 3270 ppm). Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis of magnetite reveals high concentrations of Mg, Al, Si, Mn, Ti, Cu, and Zn, with significant depletion of elements such as Ga, Ge, As, and Nb. This study refutes the hypothesis of vein-like or hydrothermal genesis, providing evidence for a sedimentary origin based on the trace element geochemistry of magnetite and LA-ICP-MS geochemical data. The Dehbid banded iron ores (BIOs) are thought to have formed under geodynamic conditions similar to those of BIOs in back-arc tectonic settings. The combination of anoxic conditions, submarine hydrothermal iron fluxes, and redox fluctuations is essential for the formation of these deposits, suggesting that similar iron–manganese deposits can form during the Phanerozoic under specific geodynamic and oceanographic conditions, particularly in tectonically active back-arc environments. Full article

This study presents a comparative numerical investigation of Reynolds-averaged Navier–Stokes (RANS) and partially averaged Navier–Stokes (PANS) turbulence models applied to the Joubert BB2 submarine geometry under steady, calm-water conditions. To assess the influence of turbulence resolution and grid density on hydrodynamic performance prediction, simulations were conducted using three mesh resolutions—coarse, medium, and fine—based on unstructured hexahedral grids. The results were validated against international benchmark data, with emphasis placed on total resistance, pressure and shear stress distributions, wake development, and vortex structure. The PANS model consistently outperformed RANS in accurately predicting total resistance and resolving wake asymmetry, especially at medium grid resolution, due to its ability to partially resolve turbulence without full reliance on eddy viscosity assumptions. It demonstrated superior capability in capturing coherent vortex structures and preserving axial momentum in the stern region, resulting in more realistic surface pressure recovery and delayed boundary layer separation. Cross-sectional and circumferential velocity distributions in the propeller plane further highlighted PANS’s enhanced turbulence fidelity, which is essential for downstream propeller performance evaluation. Overall, the findings support the suitability of the PANS model as a practical and computationally efficient alternative to RANS for high-fidelity submarine flow simulations, particularly in wake-sensitive applications where LES remains computationally prohibitive. Full article

The evolution of automation has reached marine operations in general and offshore operations in particular. Many facilities in these areas use the Internet of Things (IoT) to consolidate processes and improve data release systems. In addition, the IEC60870-5-104 protocol (IEC104) enables remote data release. This paper introduces and develops a novel IoT architecture that enables the continuous acquisition, evaluation, and release of data between platforms. Continuous data release is based on a dynamic configuration (DC) approach using the IEC104 protocol (DC-IEC104). The proposed approach thoroughly analyzes the structural model and communication process and then proposes a set of design tables according to the information object (type and amount) of the data to be released. In the application case, the data of the photoelectric composite submarine cables were successfully released with an average mean square error of 3.78 and an average processing time of 1.083 s. These results have been proven to be better compared to those obtained using three other approaches for data release. Full article

In marine seismic surveys, weak signals can be overlaid by stronger signals or even random noise. Detecting these signals can be challenging, especially when they are close to each other or partially overlapping. Several normalization methods have already been proposed, but they often lead to distortion. In this paper, we show that the unwrapped instantaneous phase of the associated analytical signal is an effective detection tool and validate it using synthetic and real data examples. This approach does not require user-defined parameters and therefore does not introduce personal bias in the results. We show that weak signals from submarine fluid plumes can be successfully detected by seismic surveys. These plumes can reveal anomalies in shallow sediments such as near-surface gas pockets and soft formations, which can severely affect offshore structures such as platforms and wind farms. Full article

This paper introduces an efficient and automated computational framework integrating Python scripting with Abaqus finite element analysis (FEA) to investigate the structural behavior of long free-spanning submarine pipelines equipped with buoyancy modules. A comprehensive parametric study was conducted, involving 1260 free-spanning submarine pipeline models, and was successfully performed with a wide range of parameters, including the length ($l_p=$ 100, 200, and 300 m), radius ($r_p=$ 0.3, 0.4, and 0.5 m), thickness, type of fluid, type of support, load ratio ($LR=$ 0.2, 0.4, 0.6, 0.8, and 1), and number of buoyancy modules ($n=$ 0, 1, 2, 3, 5, 7, and 9) with its length $(l_b=1/10·l_p)$. The study included a verification process, providing a verification of the presented framework. The results demonstrate excellent agreement with analytical and numerical solutions, validating the accuracy and robustness of the proposed framework. The analysis indicates that pipeline deformation and natural frequency are highly sensitive to variations in buoyancy arrangements, pipeline geometry, and load conditions, whereas the normalized mode shapes remain largely unaffected. Practical implications include the ability to rapidly optimize buoyancy module placements, reducing resonance risks from vortex-induced vibrations (VIVs), thus enhancing the preliminary design efficiency and pipeline safety. The developed approach advances existing methods by significantly reducing the computational complexity and enabling extensive parametric analyses, making it a valuable tool for designing stable, cost-effective offshore pipeline systems. Full article

The fall pipe rock dumping technique is extensively employed to create protection embankments around submarine cables, mitigating distortion and breakage resulting from bottom scouring. During the rock dumping operation, intricate interactions among the pipeline, rocks, and water currents can affect the stability and efficiency of the fall pipe system. This research proposed a method employing the fluid–structure interaction to analyze the interactions between the pipeline, rocks, and water currents. The paper begins with the design of an innovative fall pipe rock dumping system and presents a theoretical analysis of the applied model testing approach. The simulation parameters were determined according to the geometric, Froude, and Strouhal similarity criteria. A thorough numerical analysis was performed to investigate the hydrodynamic properties of the rockfall pipeline under fluid–structure interaction. The research examined the settling of rocks during rockfall, along with the forces and movements associated with the deposition process. The results show that the rockfall pipeline experienced vortex-induced vibrations (VIVs) caused by ocean currents during operation. The maximum settling velocity of the rocks throughout the rockfall process reached 2.2 m/s, with a final stable velocity of 1.5 m/s. These simulation results offer critical insights for improving the design and functionality of the rockfall pipeline, thereby enhancing the protection of underwater infrastructure. Full article

The submarine rudder configuration and arrangement significantly impact its hydrodynamic performance. This paper takes the SUBOFF standard submarine model as the research object, constructs a geometrically parameterized rudder fillet structure based on parabolic parametric equations, and adopts the improved delayed separation vortex (IDDES) turbulence model to carry out numerical simulation research on the submarine rounding flow field with crossed and “X” rudder configurations. By comparing and analyzing the effects of different fillet parameters and rudder layouts on the generation mechanism of the horseshoe vortex, vortex system strength characteristics, and the distribution of the wake companion flow field at the velocity of 7.161 m/s, it is found that the introduction of the rudder fillet structure can effectively destabilize the horseshoe vortex and significantly reduce the axial velocity inhomogeneity of propeller plane. In addition, the improvement effect of the flow field in the near-axis region (r/R ∈ (0, 0.5)) is particularly significant. Compared with the crossed rudder, the “X” layout shows better flow control performance, with the maximum reduction in the axial relative velocity of the propeller plane surface reaching 49.34%, which is 24.25% higher than that of the SUBOFF baseline model, and the addition of two distributions of rudder fillets can reduce the hydrodynamic noise of the submarine by 4.6 dB vs. 5.6 dB at most. The results provide an essential hydrodynamic basis for optimizing the submarine rudder system. Full article

The patterns of meiofaunal distribution in a submarine canyon and adjacent open-slope habitats at Campos Basin, southwest Atlantic, were investigated. A total of eight stations was sampled, four inside the Canyon Almirante Câmara and four on the adjacent open slope. These stations represented four isobaths (400, 700, 1000, 1300 m) and were sampled during two distinct periods (2008, 2009). At each station, three replicates were obtained and sectioned into layers of 0–2, 2–5 and 5–10 cm. Nematoda was the most abundant group in both habitats, comprising more than 85% of the total meiofauna in both sampling periods. The density and assemblage structure of the meiofauna showed high variability between the 400 m isobath and the other three isobaths in the canyon habitat. These results reinforce the roles of habitat heterogeneity and the availability of food sources as key factors strongly influencing the deep-sea meiofauna in the southwest Atlantic Ocean. Phytopigments were significantly correlated with the two major meiofaunal groups (Nematoda and Copepoda), as well as with total meiofaunal density, only in the canyon habitat. On the adjacent open slope, only copepods showed a significant correlation with sediment characteristics (mean grain size and carbonates), suggesting that distinct environmental factors influence the distribution of meiofauna in the two habitats. Full article

Submarine pipelines laid across navigational channels are highly susceptible to anchor drop impacts, which can cause deformation and disrupt normal pipeline operations. In severe cases, anchor impacts may lead to oil and gas leaks, resulting in significant economic losses and environmental damage. To ensure the safe operation of submarine pipelines, artificial rock backfilling is widely employed as a protective measure. Compared with complex pipeline protection structures, this approach is both cost-effective and efficient. In the physical model experiment, a combination of total force sensors and thin-film sensors was used to measure the dynamic response of pipelines under anchor impact. Additionally, The FEM-DEM numerical method was used to simulate the dynamic response and interaction process of anchor impact on the rock protection layer and pipeline. Numerical results were compared with experimental data to analyze the effects of rock protection layer thickness, backfill rock particle size, and pipeline sublayer types on pipeline impact response. The results show a good agreement between the physical model tests and numerical simulation studies, revealing several factors that influence the mitigation effect of the rock protection layer. This study provides a valuable scientific reference for the installation of rock protection layers for pipelines. Full article

Marine caves are complex habitats characterized by intense environmental gradients from the entrance towards the innermost dark sectors. The submarine caves at the Cape of Otranto (Mediterranean, SE Italy) host skeletonized invertebrates able to build 3D structures by intermingling their hard body parts with microbial carbonates, thus acting as bio-constructors of true marine animal forests. Complex bio-constructions named “biostalactites” (BSTs) with a core of calcareous tubes of Protula sp. (Serpulidae, Annelida) have been recently found in the dark sector of the “lu Lampiùne” submarine cave, one of the most complex and largest in the area. In the present study, we examined the outer surface of a BST from “lu Lampiùne” in order to evaluate species richness, abundance and distribution of Serpulidae at proximal, intermediate, and distal positions along the BST and on the two opposite sides of the BST with different textures (coarse vs. smooth). The BST surface hosted 1252 specimens belonging to 9 Serpulidae species differently distributed along the BST and on differently textured surfaces. As expected, sciaphilic Serpulidae dominated in terms of number of species and individuals. Remarkably, the large Protula tubes of the BST core that allowed it to grow from 6000 years ago have been largely replaced by small-sized Serpulidae species. The present study contributes to increase the knowledge of the metazoans associated with biostalactite fields from “lu Lampiùne” cave and allows for a comparison with findings from other Mediterranean BSTs. Full article

The systematic morphometric analyses of submarine mud volcanoes are widespread yet still poorly understood geological features. Our study reveals that submarine mud volcanoes show significant variability in size and geometry, independent of water depth. Specifically, the mean height-to-radius (H/R) ratio is ~0.14 ± 0.08 (±1σ). This study focuses primarily on submarine mud volcanoes in the Mediterranean, which account for approximately 58% of the dataset and include structures reaching heights of up to ~500 m with mean diameters of up to 8000 m. These edifices display a range of basal geometries, from sub-elliptical (e.g., North Alex, off the coast of Egypt) to super-elliptical (e.g., Alberto da Ottaviano in the Mediterranean Ridge Accretionary Complex). A comparative analysis of morphometric parameters distinguishes mud cones from mud pies globally, with the latter generally lacking large examples (mean diameter >10 km). The results suggest distinct evolutionary pathways, beginning with small simple cones (~100 m³ in volume), analogous to arc volcanoes in other geological settings. This study integrates fundamental marine geology with applied geohazard considerations, serving as an initial step toward enhancing shared knowledge of submarine mud volcanoes. By improving the understanding of their formation, morphometric variability, and spatial distribution, this research supports better-informed decisions regarding submarine geohazards. Full article

Seabed foundations consisting of interbedded layers of saturated soft clay and sand deposited during the Quaternary period are widely distributed in the coastal areas of Southeastern China. These soil foundations are prone to significant settlement under seismic loading. The study of the seismic dynamic response characteristics of saturated foundations with interbedded soft clay–sand and the development of rapid prediction models are essential for controlling settlement and ensuring the service safety of marine structures. A total of 4000 sets of seabed foundation models are randomly generated, with layers of saturated soft clay and sand and with a random distribution of layer thickness and burial depth. The mechanical behavior of saturated soft clay is described using the Soft Clay model based on the boundary surface theory, and the generalized elastoplastic constitutive model PZIII is used to characterize the mechanical behavior of sandy soil. The finite element platform FssiCAS is employed for a computational analysis to study the characteristics of seismic subsidence in saturated seabed foundations with interbedded soft clay–sand. A machine learning model is implemented based on the Random Forest algorithm, in which 3200 sets of numerical simulation results are used for model training, and 800 sets are used for validating the model’s reliability. The results show that under seismic excitation, the pore water pressure within the saturated seabed foundation with interbedded soft clay–sand accumulates, effective stress decreases, and the seabed foundation softens, to a certain extent. During the post-seismic consolidation phase, significant settlement of the seabed foundation occurs. The fast prediction model based on the Random Forest algorithm could reliably predict the settlement characteristics of submarine foundations. This research provides a new technological avenue for the rapid prediction of the seismic settlement of submarine foundations, which could be of use in engineering design, assessment, and prediction. Full article

Submarine groundwater discharge (SGD) refers to the flow of groundwater that enters seawater through the seabed surface at the edge of the coastal shelf. During this discharge process, seepage and initiation can easily trigger seabed instability, which significantly influences the breeding, occurrence, and evolution of marine geological events. The narrow distribution of land near the coastline and the substantial flux of groundwater discharge are closely associated with typical seabed geological events, such as submarine landslides and collapse pits, which are prevalent in the sea area. This paper analyzes the current research status of SGD both domestically and internationally, elucidates the interaction mechanisms between groundwater discharge and the seabed, and integrates existing studies on discharge-induced slope instability, collapse pit formation, and seabed erosion and resuspension. It summarizes and evaluates the existing research on the influence of seabed groundwater discharge on the evolution of seabed geological structures, identifies key scientific problems that urgently need to be addressed, and proposes future research directions that require further emphasis. Additionally, the paper conducts research on the mechanisms by which groundwater discharge affects seabed stability, providing valuable insights for the study of coastal zones in China. It also offers a scientific basis for enhancing the understanding of the generation mechanisms of marine geological events and improving the technological capabilities for their prevention and control. Full article

Cross-media vehicles, which combine the advantages of airplanes and submarines, are capable of performing complex tasks in different media and have attracted significant interest in recent years. In practice, however, cross-media rotorcrafts face numerous challenges during the cross-media transition, one of which is the complex mixed air–water flows induced by their rotors operating in close proximity to the water surface. These flows can result in aerodynamic penalties and structural damage to the rotors. The interactions between a water surface and a rotor wake bring about potential risks of cross-media locomotion, which is known as the near-water effect of rotors. Given that the distinctions between the near-water effect and the ground effect of rotors are not yet widely understood, this study details the discovery of the near-water effect and provides a comprehensive review of the evolutionary development of the near-water effect, tracing its understanding from the ground effect to the influence of droplets through aerodynamic modeling, numerical simulations, and near-water experimental studies. Furthermore, open problems and challenges associated with the near-water effect are discussed, including flow field measurements and numerical simulation approaches. Additionally, potential applications of the near-water effect for the development of cross-media rotorcraft are also described, which are valuable for aerodynamic design and cross-media control. Full article