Marine earthquakes are extremely dangerous. The Qiongdongnan (QDN) segment of the Continental Slope Fault Zone (CSFZ) in the northern South China Sea poses seismic risks that may trigger submarine landslides and tsunamis. Here, using the curved-grid finite-difference method (CGFDM), we established a dynamic spontaneous rupture model for this region southeast of Hainan Island, China. We simulated the wave propagation and strong ground motion resulting from these earthquakes and produced seismic intensity distribution maps. The maximum magnitude achieved across all models was MW7.7. A left-lateral strike-slip fault with a dip angle of 59.5° was used in the simulations, and 26 hypocenters at various positions and depths were selected. We further investigated the seismic waves and strong ground motions generated by these events. The results indicated that the velocity structure had a significant influence on the maximum slip concentration on the fault. Additionally, under the considered initial stress conditions, the earthquake magnitudes varied with depth for certain hypocenters. We analyzed the potential risk of earthquake-induced landslides using the pseudostatic method and introduced the factor of safety (FOS). The results showed that the northern landslide area contained a large section where the FOS was less than one, indicating the increased likelihood of landslides. In addition, for hypocenters at a depth of 8 km, earthquake with the smallest magnitude can generate a significantly stronger event than one with hypocenters at depths of 10 and 12 km. Overall, this fault poses significant risk for a chain of earthquake-landslide-tsunami disasters. Our study can provide a reliable reference for the development of disaster warning systems in the region and further our understanding of seismicity along the QDN segment.

Deep-water channels can deliver vast amounts of sediment from land to deep-water settings and potentially host or sequester hydrocarbon resources within associated sand-rich deposits. However, the fluid migration processes linking deep-sourced fluids with submarine channels remain poorly understood. Based on 3D seismic data from the Qiongdongnan Basin, northwestern South China Sea, this study identifies two buried channels and their underlying fluid escape systems. The channels exhibit erosional incisions, with high-amplitude anomalies at their bases, suggesting the occurrence of coarse-grained sediments. In shallower strata, extensively distributed high-amplitude reflections are interpreted as gas-bearing overbank sandy deposits, whereas some negative-polarity reflections are recognized as bottom-simulating reflectors, indicating the boundary between overlying gas hydrate-bearing sediments and underlying free gas. Erosional channel margins and adjacent enhanced amplitude reflectors further suggest that these margins serve as efficient pathways for fluid migration. Additionally, a fluid escape chimney, characterized by blanking and disrupted reflectors, has been identified beneath the channels, implying focused fluid ascent from deeper levels. Taken together, these features indicate that deep-sourced fluid migrates upward through fluid escape chimneys, accumulates at the channel bottom within sandy deposits, and subsequently disperses laterally along the erosional channel margins into the shallow horizontal overbank deposits. This coupling between submarine channels and fluid escape structures creates a complex fluid flow system characterized by diverse fluid migration pathways at different stratigraphic levels. The findings highlight the significance of submarine channels and fluid escape chimneys in fluid migration, offering insights that may be applicable to other basins.

The weathering mechanism of carbonates and its relationship with the regional carbon cycle can be affected by the involvement of sulfuric acid. Special geological conditions, being coal above and karst water below in North China, create multiple and potentially uncertain sources of sulfuric acid. Also, the high content of alkaline ions (Ca) in the atmosphere neutralizes the acid ions, forming an atypical acid rain area where the contribution of acid ions brought in by atmospheric precipitation into the groundwater is ignored. To analyze the effect of sulfuric acid on the carbon cycle, this paper assesses the potential sources and contribution of the end members by sulfur isotopes. The results show that the average contribution of gypsum dissolution, sulfide oxidation in coal measure strata, atmospheric precipitation, and agricultural fertilizer pollution to SO4 2- in karst groundwater reached 54.50%, 29.37%, 7.75%, and 8.38%, respectively. The sulfuric acid involved in carbonates solution mainly originated from sulfide oxidation in coal measure strata. Based on the spring flux, according to hydrochemical-runoff method, the net carbon sink in summer (June-July) and winter (November-December) is estimated at 0.88 t and 0.79 t, with potential carbon sources of 0.5 t and 0.69 t, respectively. Considering the submersible discharge flow, the net carbon sink can reach to 1.20 t in summer and 1.07 t in winter and sulfuric acid weathering of carbonates amounts to 0.68 t and 0.94 t. In general, sulfuric acid weathering accounted for approximately 36.23% and 46.6% of the total carbon dioxide absorption, indicating that sulfuric acid contributes significantly to carbonates rocks weathering, and weakens the karst carbon sink effect. Therefore, anthropogenic processes such as mining activities can accelerate carbonates weathering and influence the carbon cycle greatly.

Although passive continental margins have long been regarded as low seismicity and with limited tsunamigenic potential, historical records reveal that active faults within these tectonic settings can, in fact, generate tsunamis. Firstly, this study evaluates the tsunamigenic potential of the Qiongdongnan segment of the Continental Slope Fault Zone (QDN-CSFZ), a newly identified intraplate fault in the northern South China Sea (SCS). We constructed 280 earthquake scenarios (Mw 6.6–8.0) with different source mechanisms and incorporated a stochastic source model to capture heterogeneous rupture patterns. Our simulations reveal that tsunami wave propagation is governed by regional bathymetry, causing waves to travel mainly perpendicular to the fault strike and rapidly across deep basins toward the Xisha Islands. Earthquakes above Mw 7.4 on the QDN-CSFZ generate regionally significant tsunamis. Under the extreme Mw 8.0 scenario, maximum tsunami wave amplitudes could be >7 m at the Qiongdongnan, >6 m at the Xisha Islands, and >5 m at the Vietnam Coast. The QDN-CSFZ constitutes a “multi-mechanism, short-lead-time” near-field tsunami threat, which is fundamentally distinct from the “high-potential, long-lead-time” far-field threat associated with the Manila Subduction Zone. This study underscores the need for a paradigm shift in tsunami assessment and for developing tailored near-field warning systems in the northern SCS.

Earthquakes are recognized as the primary cause of submarine landslides. These earthquake-induced submarine landslides can damage seafloor infrastructure (e.g. submarine cables, oil pipes and rigs) and trigger anomalous tsunamis that cannot be explained solely by coseismic deformation. However, due to their underwater occurrence, earthquake-induced submarine landslides are difficult to observe and measure directly, and current understanding of their characteristics and triggering mechanisms remains limited compared to earthquake-induced terrestrial landslides. Historical instances of anomalous tsunamis and submarine cable breaks following earthquakes provide valuable insights into earthquake-induced submarine landslides. This study reviewed 124 global events of anomalous tsunamis and submarine cable breaks following earthquake occurrences since 1900 using the National Oceanic and Atmospheric Administration tsunami database and systematic literature review. The study compiled key parameters of earthquake-induced submarine landslides associated with anomalous tsunamis and submarine cable breaks, such as locations, initial water depths of the headscarp, average seabed slope angles, volumes and landslide types. This study also obtained seismic parameters such as epicentral distances, peak ground acceleration (PGA) and Modified Mercalli Intensity (MMI) from the USGS-ShakeMap to establish a quantitative relationship between earthquake-induced submarine landslides and their seismic triggering parameters. Additionally, a comparison was made between earthquake-induced submarine landslides and earthquake-induced terrestrial landslides with emphasis on differences and similarities in landslide parameters, earthquake magnitudes, seismic parameters PGA and MMI, earthquake magnitude-maximum epicentral distance relationships and triggering mechanisms. It was observed that most of the earthquake-induced submarine landslides occur in shallow nearshore areas and generate tsunamis characterized by high local wave heights. This attribute leaves little or no time for warning and preventive measures. Earthquakes with onshore epicenters or strike-slip mechanisms that trigger submarine landslide tsunamis pose an additional challenge for early warning systems. Compared to earthquake-induced terrestrial landslides, earthquake-induced submarine landslides typically occur on gentler slopes, have larger volumes, are triggered by smaller earthquake magnitudes and exhibit distinct triggering mechanisms. However, they show more similarities than previously anticipated, particularly in terms of seismic parameters (PGA and MMI) and focal mechanisms. The findings of this study contribute to a better understanding of earthquake-induced submarine landslide characteristics and their quantitative relationship with seismic parameters. It highlights the necessity for further research on anomalous tsunamis and submarine cable breaks following earthquakes in order to improve current understanding of triggering mechanisms, frequencies and hazard potential of earthquake-induced submarine landslides. Moreover, given that studies on both earthquake-induced submarine landslides and earthquake-induced terrestrial landslides explore interconnected scientific questions within a unified framework, this study emphasizes the importance of comparing submarine and terrestrial environments in earthquake-induced geological disaster research.

Earthquake-induced landslides, both nearshore terrestrial and submarine, can generate tsunamis, exemplifying a common type of cascading marine geohazards. These events pose significant risks to marine infrastructure such as subsea communication cables, oil and gas platforms, pipelines and rigs, as well as to coastal communities and ecosystems. Recent incidents such as the landslides and tsunamis triggered by the 2018 Sulawesi earthquake in Indonesia highlight the urgency of addressing these hazards. However, compared to terrestrial cascading disasters, research on marine cascading hazards is constrained by data acquisition challenges, limiting insights into their triggers and cascading impacts. To fill the research gap, this study conducted a systematic literature review and developed a database of 93 global earthquake-landslide-tsunami cascades since 1900. Key parameters of earthquakes, landslides, and tsunamis were compiled and summarized, with detailed analysis of 20 representative cases, focusing on their triggering mechanisms and cascading effects. Based on the initial location of the landslides, we classified cascades into three categories: Nearshore terrestrial cascades: Seismic shaking destabilizes coastal slopes, triggering landslides or rockfalls that displace materials into water at high velocity, generating tsunamis. Nearshore submarine cascades: Seismic shaking induces liquefaction of saturated sediments nearshore marine area, causing liquefied gravity flow and tsunami generation. Submarine cascades in deeper waters (similar to 200 m or more): Seismic shaking triggers translational landslides or slumps of fine-grained sediments, deforming the seafloor and generating tsunamis. Despite advances in understanding co-seismic landslide-tsunami cascades, significant challenges remain, particularly in early warning and hazard assessment. Current tsunami warning systems primarily target tectonic tsunamis and are not wellequipped to warn localized tsunamis caused by co-seismic landslides. The short lead time, often just seconds to minutes, between an earthquake and the arrival of landslide-induced tsunamis further complicates warnings. Current methods for assessing submarine slope stability during seismic shaking fail to adequately capture the complex responses of slopes to seismic forces. Moreover, the lack of real-time monitoring hinders the accurate collection of data on submarine landslides, thereby restricting the precise assessment of cascading hazards. This study highlights the importance of future research on the interconnected multi-physical processes between earthquakes, landslides, and tsunamis. Developing integrated multi-physical models to assess these interactions, along with creating comprehensive research frameworks through interdisciplinary collaboration are critical. These efforts will enhance current understanding of cascading marine geohazards and provide new theoretical and technical support for early warning and hazard assessment. In particular, based on global case studies, this study highlights the critical need to assess the risks of earthquake- landslide-tsunami cascades in the northern South China Sea. The two active fault zones in the region, the Littoral Fault and Continental Slope Fault, both have the potential to generate destructive earthquakes. Coupled with the region's abundant sedimentary deposits, these factors significantly increase the likelihood of cascading hazards along the northern South China Sea continental slope. Furthermore, the South China coastal region is one of China's most economically developed areas, encompassing densely populated regions such as the Guangdong-Hong Kong-Macao Greater Bay Area and the Hainan Free Trade Zone, along with critical infrastructure. A destructive tsunami in this region could have catastrophic consequences. In conclusion, the study of earthquake-landslide-tsunami cascades involves multiple disciplines, including seismology, geology, mechanics, fluid dynamics, numerical modeling, artificial intelligence and social sciences. Advancing early warning, assessment and management of these cascading hazards requires interdisciplinary collaboration and the development of comprehensive research frameworks.

The consensus in earlier studies was that the tsunami threat along the coast of south China primarily comes from destructive earthquakes occurring in the Manila subduction zone. However, two seismogenic structures on the continental shelf of the Northern South China Sea, namely the Littoral Fault Zone and the Slope Fault Zone, have been overlooked in these assessments. Both fault zones have a history of destructive earthquakes accompanied by tsunamis. In particular, the Slope Fault Zone, located in the shelf-slope bending zone, is prone to triggering submarine landslides after earthquakes, which can result in devastating tsunamis. This study aims to assess the potential threats posed by earthquake-submarine landslide-tsunami cascading events in the Qiongdongnan segment of the Slope Fault Zone to the coastal regions of Southern China.To achieve this, we conducted a probabilistic seismic hazard analysis using the latest findings on the fault structure of the Qiongdongnan segment and the comprehensive regional seismic catalog. This analysis provides important information about the likelihood of earthquakes in the region. Based on the seismic hazard analysis results, we assessed the stability of gentle slope areas (submarine landslide gap) using high-resolution bathymetric data, multi-channel seismic profiles, and gravity core samples of seafloor sediments. Finally, we established a model for potential submarine landslide sources in these areas and evaluated the tsunami hazard resulting from earthquake-triggered landslides.By comprehensively evaluating earthquake-submarine landslide-tsunami cascading events on the continental shelf fault zone of the Northern South China Sea, this study aims to provide a new perspective and understanding for earthquake and tsunami disaster prevention. Additionally, it seeks to establish the scientific foundations for the development of effective tsunami warning and risk management strategies.

This study assesses urban flood resilience at the subdistrict scale in Shenzhen, China, addressing the lack of fine-grained spatial analysis in existing city-level models. A multidimensional framework integrating natural geography, infrastructure, socioeconomics, emergency management, and risk exposure was constructed, with indicator weights derived from a hybrid Analytic Hierarchy Process–Entropy Weight Method. Spatial autocorrelation analysis (Moran’s I = 0.475, p < 0.001) revealed distinct “resilience fault lines,” with high-resilience clusters in central districts and low-resilience clusters in peripheral industrial belts. Geodetector identified economic intensity (q = 0.46), elevation (q = 0.39), and emergency shelter density (q = 0.37) as dominant drivers, with strong interaction effects. These findings highlight significant resilience inequality, emphasizing the need for targeted, multidimensional interventions to enhance adaptive capacity and inform climate adaptation strategies in rapidly urbanizing coastal megacities.

Plastic pollution is at the forefront of environmental problems, and has invaded every sphere on Earth. We describe the abundance, distribution, transport pathways and mechanisms, fate and ecological impacts of plastics in the South China Sea (SCS), emphasizing on the deep seafloor microplastics and plastics. We document presence of plastics, primarily based on more than 100 dives in manned submersibles, backed-up by in-depth analysis of dive track videos and images from all locations, providing the first distribution maps of microplastic and plastics on the bottom of the SCS. Abundance of large plastics have been observed to be highest at typical V-shaped geomorphological units, such as canyons, where hydrodynamic conditions are stronger. However, high concentrations of microplastics occur commonly in the sediments of coastal zones. Sources and transportation mechanism of microplastics and plastics in the SCS are thus distinctly different from each other. While a vast majority of microplastics is possibly transported through riverine inputs, most of plastics have a sea-based origin and are discarded from fishing boats, entertainment vessels, and merchant ships. Apart from surface currents, deep-water, seasonal currents, as well as gravity flow, facilitate the transport of marine plastics to deep seafloor sediments. We present two types of models for the transportation of microplastics and plastics in SCS, respectively. We further elucidate the ecosystem which has emerged as a new hot spot with the plastics in SCS. Both large plastics and microplastics additionally act as vectors of chemical pollutants, resulting in ecotoxicological damages. Interaction of biota with deep-sea plastics has been observed and documented in terms of ingestion, entanglement, or proximity, resulting in potential negative effects. The extent of plastic pollution in the SCS is at an alarming level. Therefore, strengthened mitigation procedures, reuse and recycling structures, and waste water management have to be urgently incorporated in National Action Plans to control the burden of plastics entering the SCS.

Since 2018, several "atypical" tsunami events have occurred globally. These events include the 28 September 2018 Palu Bay tsunami in Sulawesi, triggered by a Mw-7.5 strike-slip earthquake, which led to more than 4300 deaths; the 22 December 2018 tsunami event, caused by the flank collapse of Anak Krakatau volcano in the Sunda Strait, Indonesia, that killed 437 people; the 30 October 2020 Samos tsunami event in the Eastern Mediterranean Basin, the largest since 1956, originating from the Mw 6.9 normal fault earthquake located in the northern Samos Island to the east of the Aegean Sea; the 2022 Tonga tsunami event generated by the VEI 5 explosive eruption of Hunga Tonga-Hunga Ha'apai submarine volcano in the South Pacific; and the 2023 Turkey-Syria tsunami event triggered by the onshore strike-slip earthquake which induced a 40-cm wave amplitude. Currently, scientists have limited understanding of the generating mechanisms and physical processes of these "atypical" tsunami sources, and existing disaster response systems are unable to react promptly to these "unexpected" extreme events, resulting in casualties and economic loss. Hence, this paper aims to provide an in-depth analysis of the triggering mechanisms of these "atypical" tsunami events. Factors contributing to the formation of these "atypical" tsunamis and their complexities include the formation of landslide tsunamis from the cascading effect of earthquakes-induced liquefaction of coastal/submarine sand, distinct coastal morphology and complex coupling effect of atmosphere-ocean-land interactions accompanied by intense volcanic activities. These findings challenge our conventional understanding that tsunami generation requires large-scale vertical deformation, which is commonly associated with submarine earthquakes. With this newfound knowledge, strike-slip earthquakes, onshore earthquakes near the coast, and intense volcanic eruptions can all be classified as potential tsunami sources due to the chain effect. A careful review of historical documents detailing the major earthquakes in the northern South China Sea (hereinafter, SCS) and volcanic tsunami events in the surrounding region suggests that SCS and its surrounding regions are not lacking in such "atypical" tsunami events. Historical documents reveal that a majority of major historical earthquakes in the northern SCS, that were accompanied by tsunami phenomena, are documented in local records and genealogies. These events include the 1605 M 7.5 Qiongzhou event, the 1604 M 8.0 Quanzhou event, the 1918 M 7.5 Nanao event, the 1992 Hainan event and the 1994 Taiwan Strait earthquake event. Historical and modern instrumental records have also identified 22 volcanoes in this region that are responsible for 41 past tsunami events, accounting for 24% of the global historical volcanic tsunami events. These tsunami-triggering volcanoes are mainly located along the Philippine Island Arc and the Sunda Island Arc. Notable examples include the lliwerung volcano in the southern part of the Banda Sea along the eastern Sunda Island Arc, Teon volcano and Ijen volcano in central Java Island, and the Agung volcano and Peuet Sague volcano in western Sumatra Island. Lessons learnt from recent and past "atypical" tsunami events highlight the need for more effective tsunami warning operations, which in turn require a better scientific understanding of the tsunami genesis of those potential "atypical" sources. In the SCS and its surrounding region, future research should prioritize several key aspects: (1) Conducting detailed marine geophysical surveys to better understand the geometry and seismogenic behaviours of active faults; (2) understanding the triggering mechanism of cascading hazard effects through in situ monitoring and seafloor surveys; (3) developing theoretical and numerical approaches to reproduce the complex generation processes of volcanic tsunamis.

Fault activities in sea areas always produce devastative marine geohazards. For marine geohazard assessment, it is important to know the location, geometric structure, and activity regularity of active faults. In this study, highresolution multi -channel seismic and topographic data are used to investigate the exact location, geometric structure and latest activity of the Continental Slope Fault Zone (CSFZ) in the northern South China Sea. The results show that the Qiongdongnan (QDN) segment of the CSFZ is a 194 km long NEE -trending fault zone that developed near the transition of continental shelf and slope. In its geometric structure, the CSFZ (QDN segment) cuts through the Cenozoic basement and breaks upward to near the seafloor with high -angle dip. According to whether it ruptures to the seafloor, it can be divided into eastern and western segments. In the western segment, the fault scarps about 8 similar to 9 m high can clearly be seen on the seafloor. Whereas in the eastern segment, the fault shows a blind characteristic below the seafloor. The analysis of fault throws and expansion indices show that CSFZ (QDN segment) have remained active since the late Pleistocene. Due to the CSFZ is an active fault and geographically adjacent steep slope, which may cause large interpolate landslides, and then leading to destructive tsunamis. As a result, the CSFZ has great seismogenic potential and may produce marine geohazard chain. Thus, it is of great significance to the assessment of marine geohazard chain posed by the CSFZ for improving hazard mitigation.

In the northern region of the South China Sea, located at the intersection of the continental shelf and slope, there have been recorded four earthquakes with magnitudes M≥6.0. This pattern of seismic activity suggests the presence of a previously unidentified active submarine fault. Notably, no active faults have been documented in this area prior to our investigation, with earlier studies predominantly focusing on the structural morphology and sedimentary basin evolution associated with the South China Sea's spreading phenomenon. Through the examination of seismic profiles and historical earthquake records, we have identified a newly discovered fault, termed the Slope Fault Zone (SFZ). The SFZ exhibits diverse structural components, including a listric normal fault in the western sector and a strike-slip fault zone in the eastern sector. Analysis of shallow seismic profiles and borehole data has revealed that the SFZ intersects with strata from the late Pleistocene epoch, confirming its classification as an active fault. The derived fault parameters indicate that the western segment of the SFZ has the potential to generate earthquakes of considerable magnitude, ranging from M 6.7 to 7.2. Furthermore, given the significant occurrence of submarine landslides along the southern boundary of the SFZ, there exists a risk that such seismic events could trigger slope failures and subsequent tsunamis. In summary, our research has unveiled the presence of an active fault capable of precipitating submarine earthquakes, landslides, and tsunamis.

Manned submersible dives in the northwest South China Sea encountered substantial amounts of plastic litter accumulated at the base of scours along the floor of a submarine canyon, which may associate with the depositional behaviors of turbidity currents. In this study, we conduct numerical simulations using field-scale bathymetry to investigate the relationship between the canyon floor morphology, flow processes, and the locations and sizes of the plastic litter piles. The consistent deposition pattern caused by the numerical turbidity currents with different input parameters indicate that morphology of the canyon may exert a dominant influence on turbidite deposition. This is attributed to a significant reduction in shear velocity as simulated turbidity currents flowing through the scours on the canyon floor. Spatial correspondence between deposits of turbidity currents and plastic litter accumulation suggests that suspended sediments and plastic may undergo simultaneous dynamic processes during the transportation of turbidity currents. The issue of marine plastic litter has attracted wide attention, particularly in terms of its transportation mechanisms and locations of accumulation on the ocean floor. Turbidity currents are subaqueous sediment-gravity flows that can transport large amounts of sediment, nutrients and pollutants into the deep sea, yet there is sparse research on the dynamics of plastic litter transport under the control of turbidity currents, and its accumulation in the deep sea. Here, we present a series of numerical simulations of turbidity currents in a submarine canyon with various input parameters, when combined with observational data on topography and plastic litter distribution, confirm that turbidity currents constitute a plausible mechanism for the transport of plastic litter and for its accumulation in response to changes in flow associated with scours. In addition, we find that the concavity of the scours is also necessary for plastic litter accumulation, since it induces significant fluctuations in the shear velocity and the corresponding depositional process. Numerical simulations were applied to investigate turbidity currents as a cause for plastic litter accumulations in a submarine canyon The simulated turbidite deposits and observed plastic litter accumulations exhibit a strong spatial correspondence The morphology of the canyon floor may exert dominant influence on the plastic litter accumulations in submarine canyons

ABSTRACT Traditional mapping of bedforms in submarine canyons relied on vessel‐mounted and towed sensors, but their fine‐scale geomorphology and shallow structure requires higher resolution datasets. This study utilizes a high‐resolution dataset obtained from an autonomous underwater vehicle, combined with seismic reflection profiles and sediment cores, to analyse bedform sets within a 25.6 km long submarine canyon (canyon C14) in the northern South China Sea. A train of crescent‐shaped axial steps, indicative of cyclic steps formed by supercritical turbidity currents, is imaged along the canyon. Axial steps in the upper course show erosional truncations and sub‐horizontal reflectors on the lee and stoss sides, respectively, pointing to erosional–depositional cyclic steps formed by confined flows with high erosional capacity. This is facilitated by canyon narrowness and steeper axial gradient. After a transition segment, the lower course widens, with a gentler axial gradient, resulting in increased asymmetry and wavelength of axial steps. Backset bed deposits on the stoss sides of these steps indicate depositional cyclic steps with higher aggradation. Sediment filling, almost padding each cyclic step associated scour suggests the reworking of previously formed bedforms by gravity flows fed by destabilization processes on the canyon sidewalls and upstream lee faces and, possibly, by shelf‐edge and uppermost slope spillover into the canyon. At the lowermost course, cyclic steps transition to a furrow field, likely associated with flow velocity reduction facilitated by canyon floor widening and a further decrease in slope gradient. Flow braiding and re‐convergence, related to the erosion of fine‐grained deposits within the canyon floor, should have played a role to produce furrows under supercritical conditions. This work enhances our understanding of the detailed morphology and shallow relief configuration of bedforms in deep‐water submarine canyons, providing insights into their causative processes and evolution.

Submarine canyons are prominent features on continental margins, acting as major conduits for sediment transport primarily through turbidity currents. Understanding how these currents interact with complex canyon topographies is crucial for deciphering the canyon system evolution, yet challenging due to limited field observations. Focusing on a group of slope-confined canyons within the Pearl River Mouth Basin, northern South China Sea, this study integrates multibeam bathymetry, core analysis, and process-based Computational Fluid Dynamics (CFD) modeling to investigate the influence of realistic canyon topography on turbidity current dynamics and resulting sediment deposition. Analysis of core samples revealed a potential turbidite layer characterized by silts and sandy silts. Using these sediment information and bathymetric data, we conducted a series of three-dimensional CFD simulations. Our findings highlight the significant variability in turbidity current characteristics, particularly flow velocity and sediment concentration, within the canyon groups. This variability is primarily controlled by canyon head depth, the width-to-relief ratio, and slope gradients. Notably, the simulations revealed unique flow structures not typically observed in experimental settings, including unidirectional flows, small-scale helical flows, stacked and mixed flow cells, and flow separation and convergence across inter-canyon ridges. Our CFD simulations also revealed a distinct near-wall pattern of linear deposition of coarse-grained sediments, which is similar to the observed bathymetric changes between 2009 and 2017. Based on the consistent results, we propose a conceptual model wherein differential erosion, driven by oceanographic processes, plays a key role in shaping the observed linear depositional patterns.