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The impact of gas hydrate dissociation on submarine landslides has become an increasingly significant issue. However, previous models cannot interpret the newly discovered non-conformity between the slide surface and the base of the gas hydrate stability zone. Here, the authors design an experimental approach for visualising fluid migration during hydrate dissociation at atmospheric pressure. The results identify the lateral and vertical fluid migration pathways. Weak layers propagate nearly laterally beyond the hydrate zone, which lengthens the potential slide surface. Vertical pathways branch and deviate from their original paths, generating a shallower slide surface. Furthermore, the findings show that fluid overpressure under the overlying layer leads to steepening slopes. The lubrication effect and the underestimated inclination of slopes at failure may account for the low-angle failure of clay slopes. The results support a new conceptual model that reconciles the non-conformity between the slide surface and the base of the gas hydrate stability zone and offer a new perspective for the large-scale failure of low-angle submarine slopes. It will be interesting and important to confirm these implications in the future.

Submarine landslides can be triggered by several processes and involve a variety of mechanisms. These phenomena are important sediment transport processes, but they also constitute a significant geohazard. Mapping of the southwestern Caribbean Sea using 3D seismic data has allowed identification of several submarine landslides in the Colombian Margin in the area dominated by the Southern Sinú Fold Belt (SSFB). A poststack depth-migrated seismic cube survey with a 12.5 by 12.5 m bin spacing was used to identify landslides in an area covering 5746 km2. Landslides were interpreted using a seafloor morphologic parameter identification process and the internal deformation of the slope-forming material, as seen from seismic data. A total of 93 landslides were identified and classified based on their movement styles as follows: 52 rotational, 29 translational, and 12 complex landslides. In addition, 12 distinct deformational zones and a zone of mass transport complex (MTC) were identified. Five different ground condition terrains were interpreted based on landslide type and distribution as well as in geologic structures and seismic reflection analysis. Two main processes seem to influence landslides in the study area. First is the folding and faulting involved in the SSFB evolution. This process results in oversteepened slopes that start as deformational zones and then fail as translational or rotational slides. Those individual landslides progressively become complex landslide zones that follow geologic structural orientation. Second is the continental shelf break erosion by debris flows, which fills in intraslope subbasins and continental rise with several MTCs. According to the results, risk of damage by landslides increases in distances shorter than 4 km along structural ridge foothills in the study zone.

Evaluation of wave impacts on submarine landslides is an essential element in geohazard studies. The slight desaturation of sediments (due to dissociation of gas hydrates) has been found to adverse...

Submarine landslides are a ubiquitous geohazard in the marine environment and occur at multiple scales. Increasing efforts have been made during the last decade to catalogue and categorise submarine landslides in comprehensive databases, aiming to better understand their preconditioning and trigger factors. Using the recently compiled, open-access MAGICLAND dataset, we investigate the distribution and morphometric trends of submarine landslides observed in seven distinct geomorphologic domains offshore west and southwest Iberia. Higher densities of submarine landslides occur on the proximal regions of the south and southwestern margins of the study area. These regions are located adjacent to or coincident with higher density areas and clusters of earthquake epicentres. Submarine canyons are another major location for collapses which are particularly abundant at canyon mouths. However, significant numbers occur within all domains with pronounced relief, including distal regions hundreds of kilometres away from the foot of the continental slope. Landslide size range is inversely proportional to their spacing and frequency, a tendency observed within each domain on the whole study area. Positive correlations were obtained between the parameters analysed, but relationships between unidimensional parameters such as length and width exhibit lower correlation coefficients. Correlations between 2D and 3D parameters such as area and volume are stronger, supporting similar findings by other studies. The relationships obtained are, however, variable across domains, and the correlation values are influenced by the seafloor geomorphology. This work brings new insights on submarine landslide distribution in the understudied west and southwest Iberian continental margin, complements previous inventories made for nearby regions, and provides valuable data with wider applications for submarine landslide databases.

Landslide-induced tsunamis are common natural hazards that potentially affect the safety and stability of waterfront structures. A numerical tank was constructed using FLOW-3D to investigate the hydrodynamic response of the sea-wall subjected to artificial submarine landslide-induced tsunamis, including the hydrodynamic load and wave run-up height. Initially, the landslide-induced tsunami model was calibrated using experiments to ensure high accuracy for capturing the free surface and obtaining the flow field information. Then, the sea-wall was added into the numerical tank to study the hydrodynamic response of the sea-wall. The results show that the artificial landslide successively generated two wave crests and that the hydrodynamic response of the sea-wall under the second crest was stronger than that under the first crest. Additionally, the effects of different influencing factors on the hydrodynamic response were discussed, respectively, and prediction equations for the hydrodynamic response considering these factors were proposed.

Many landslides in nature may be classified as deformable landslides. The landslide volume is usually modeled as a rheological material when SPH methods are used for landslide simulation, since these methods allow for the use of particles with different fluid properties. To increase the accuracy, the Carreau-Yasuda model is chosen in this study to predict the behavior of the rheological material. This rheological model overcomes the weakness of the power-law model in predicting the viscosity at zero and infinite shear strain rates. Also, a fully explicit three-step algorithm is proposed to solve the governing equations. In the first step, the momentum equation is solved in the presence of the body forces while neglecting all other forces. In this step intermediate velocity values are computed. In the second step, the calculated intermediate velocities are employed to compute divergence of the stress tensor, and velocity components of each particle are updated to find their intermediate positions. These two steps are called predictor steps. In the third, corrector step, the pressure gradient in the momentum equation is merged with the continuity equation, and lastly the final particle velocity is calculated at the end of the time step. The fully explicit three-step algorithm is used in combination with Carreau-Yasuda model to simulate the submarine non-rigid landslide from the physical model. The comparison with the experimental data indicates good agreement between the calculated and observed water surface elevations with very low L2 relative error norm (L2) and RMSE values that are up to 70% lower than those from previous studies when Cross and Bingham rheological models were used with ISPH and WCSPH models, respectively. Moreover, the shape and the advancement of the non-rigid body made of sand are captured equally good. Ovo je recenzirana verzija rada pre konačnog slaganja teksta za časopis.

Marine geological disasters occurred frequently in the deep-water slope area of the northern South China Sea, especially submarine landslides, which caused serious damage to marine facilities. The cyclic elastoplastic model that can describe the cyclic stress-strain response characteristic for soft clay, is embedded into the coupled Eulerian-Lagrangian (CEL) algorithm of ABAQUS by means of subroutine interface technology. On the basis of CEL technique and undrained cyclic elastoplastic model, a method for analyzing the dynamic instability process of marine slopes under the action of earthquake load is developed. The rationality for cyclic elastoplastic constitutive model is validated by comparing its calculated results with those of von Mises model built in Abaqus. The dynamic instability process of slopes under different conditions are analyzed. The results indicate that the deformation accumulation of soft clay have a significant effect on the dynamic instability process of submarine slopes under earthquake loading. The cumulative deformation is taken into our model and this makes the calculated final deformation of the slope under earthquake load larger than the results of conventional numerical method. When different contact conditions are used for analysis, the smaller the friction coefficient is, the larger the deformation of slopes will be. A numerical analysis method that can both reflect the dynamic properties of soft clay and display the dynamic instability process of submarine landslide is proposed, which could visually predict the topographies of the previous and post failure for submarine slope.

The complexity of the Kaikōura earthquake rupture and tsunami generation presented a unique opportunity to examine and learn from a modern event. This paper reviews how the five years of research f...

Iceberg discharge influences ocean circulation, affects climate and increases global sea level. Icebergs are also known to gouge the seafloor in water depths limited by their keel depth, thus representing a hazard to subsea infrastructure. Here, we provide evidence that icebergs can affect the seafloor at depths greater than their keel depth by triggering submarine landslides. Using repeat bathymetric surveys from multibeam echo sounders, we investigate the cause of a submarine landslide that occurred in Southwind Fjord, Baffin Island, between September 2018 and September 2019. This landslide is shown to be closely associated with recently formed iceberg pits at its headscarp carved by an iceberg that grounded and that capsized in the fjord in early September 2018. Geotechnical data from a nearby sediment core indicate that the vertical loading induced by the iceberg grounding and capsizing is sufficient to trigger the observed landslide. These results imply that icebergs originating from the Arctic, Greenland and Antarctica are hazards thousands of kilometres away from their original source and can affect continental slopes by triggering submarine landslides. This process represents an additional source of marine geohazards, especially if climate change leads to increased iceberg discharge. Iceberg gouging of continental slopes can initiate submarine landslides, potentially far from the iceberg source region, according to observations and geotechnical analysis of an event in a Baffin Island fjord.

On September 28 2018, an Mw 7.5 strike-slip earthquake occurred to the north of Palu Bay on the Sulawesi Island, Indonesia. This triggered a destructive tsunami within the bay, which reached Palu city. Simulation have been conducted to investigate the landslide source. However, the tsunami should be investigated considering a physical model in the area where detailed bathymetric survey had not been conducted. In this study, we investigated the impact of coastal landslides on the southern part of the bay using a two-layer model. Owing to the increasing collapse volume, the southern west coastal landslide could approximately explain the observations in Palu city. However, the calculated mass volume of the source largely overestimated the bathymetric survey data. Hence, we considered the possibility of submarine landslide in the southern part of the bay and the simulation results could approximately explain the maximum tsunami heights in the southern part of the bay. These results suggest that more detailed multibeam data will be required to investigate the possible submarine landslide in the southern area which could induce a destructive tsunami reaching Palu city within a few minutes after the collapse.

Submarine landslides are a major geohazard among worldwide continental slopes, posing significant threats to offshore infrastructure, marine animal habitats and coastal urban centres. This study establishes an original numerical package for time-efficient modelling of the entire submarine landslide evolution covering the pre-failure shear band propagation, slab failure and post-failure dynamics. The numerical scheme is based on the conservation of mass and the conservation of momentum and combines the shear band propagation theory and the depth-integrated method, with the consideration of the drag force from the ambient water. Shear band propagation in the weak layer and slab failure in the sliding layer are controlled by the strain softening and rate dependency of the corresponding undrained strength parameters. The post-failure behaviour in the sliding layer, such as retrogression upslope and frontally confined and frontally emergent mechanisms downslope, is also simulated. The numerical results from the proposed method are comparable to the analytical solutions and the large deformation finite element analysis. Application of this method to a back analysis of the St. Niklausen slide in Lake Lucerne reproduced the observed shape of the mass transport deposits, the position of the main scar and the travel distance. Because of its easy implementation and efficiency, the proposed numerical method for modelling of submarine landslides seems promising for practical applications., Landslides, 18 (9), ISSN:1612-510X

Submarine landslides are a great hazard to offshore pipelines. The comparison and optimisation of pipeline routing schemes to reduce the potential submarine landslide risk is a key issue in offshore oil and gas development engineering. This paper presents an improved group decision-making evaluation method for offshore pipeline routing optimisation in areas prone to submarine landslides. An information integrity variable is proposed to adjust the relative weight of each factor considering the incompleteness of the engineering geological survey information and data. The credibility level of each expert involved in the evaluation, which is calculated based on the similarity and difference of the experts’ judgment matrices, is introduced to correct the information integrity variable, relative weights, and memberships. The group decision-making for offshore pipeline routing selection is then obtained based on the principle of the majority rule. Finally, a case of pipeline routing optimisation in the submarine canyon area of the Baiyun depression, northern South China Sea, is assessed by using the proposed method. The result shows that the proposed group decision-making method can enhance the objectivity of the assessment for the offshore pipeline routing optimisation under a subjective environment.

Tsunami waves were observed along the Bulgarian Black Sea coastline on 7 May 2007. The maximum rise and fall of the sea level were 1.2 and 2.0 m, respectively, with wave oscillations between 4 and 8 min. At first, submarine landsliding and then later on atmospheric disturbance were suggested as the cause of the tsunami. Numerical modeling, assuming a landslide displacing 30–60 million m3 material on the slope with a thickness range of more than 20–40 m, could reproduce the main characteristics of the recorded tsunami. In this early model, the landslide initiated on the shelf at a water depth of 100 m with a runout of approximately 20 km into 1000 m water depth. Subsequent and recent numerical modeling suggested that the failure may have initiated on the slope, anywhere between 200 and 1500 m seafloor depth. The runout of the transported sediments in these latest model was at 1850 m water depth. Just a few years after the tsunami, OMV and its joint venture partners, TOTAL and Repsol, acquired modern deepwater data sets in the same area where the submarine landsliding was assumed to occur. These data sets included multibeam swath bathymetry area and 3D reflection seismic data. These data sets offer a possibility to establish the presence of speculative submarine landslide responsible for the tsunami, with its geometry and nature. Our results provide direct evidence for the occurrence of large nonseismic catastrophic sediment failures along the Bulgarian coast. In this study, we illustrate Quaternary submarine landslides on 3D seismic reflection data immediately below the one responsible for the 2007 event; we also briefly point out the potential interpretation pitfall related to sediment waves and mass transport complexes.

On December 22, 2018, a destructive tsunami related to the phenomena caused by the volcanic eruption of Gunung Anak Krakatau (GAK) was generated following a partial collapse of the volcano that caused serious damage and killed more than 400 people. This recent event challenged the traditional understanding of tsunami hazard, warning and response mechanisms and raised the topic of volcanic tsunami hazard. The complex mechanism of this tsunamigenic volcano collapse still needs further investigation as Anak Krakatau is one of the potentially tsunamigenic volcanoes in the world. This study investigates the possible source mechanisms of this phenomenon and their contribution to explaining the observed sea level disturbances by considering the impacts of this destructive event. We configured a flank collapse scenario with a volume of 0.25 km3 as a combination of submarine and subaerial mass movement as the possible source scenarios to the December 22, 2018 Sunda Strait tsunami. A two-layer model is applied to simulate the tsunami generation by these landslides up to 420 s. The tsunami propagation and inundation are then simulated by NAMI DANCE model in GPU environment. The simulation results suggest that this scenario seems capable of generating such a tsunami observed along the coast of Sunda Strait. However, the contribution of the possible submarine mass movements in the close area between GAK and the surrounding islands either to this event or potential tsunami threat in the region is still questionable. We employed a bathymetric dataset through pre- and post-event analyses, which demonstrate submarine slope failures in the southwestern proximity of GAK. Hence, additional two scenarios of elliptical landslide sources on the slopes of bathymetry change area (could be triggered by seismic motion/volcanic eruption) are considered, searching for the possible effects of the tsunami that might be generated by these submarine landslides. The study may also provide some perspective for potential tsunami generation by combined sources and help to elucidate the extent of volcanic tsunami hazard in the region due to potential future eruptions of Gunung Anak Krakatau.

Submarine landslides in gas hydrate areas are a significant geo-hazard that can cause considerable damage. The processes and mechanism of submarine landslides caused by gas hydrate dissociation are not clearly understood. Therefore, we designed a micro-electro-mechanical systems (MEMS) accelerometer array to study and monitor the deep displacement of submarine landslides. The MEMS accelerometer array consists of several gravity acceleration-sensing units that are protected and positioned using a flexible circuit board and elastic steel tape, such that all the units are connected to an Inter-Integrated Circuit (IIC) communication bus. By sensing the three-axis tilt angles, the direction and magnitude of the displacement for a measurement unit can be calculated; then, the overall displacement of the array is calculated as the difference in the displacements from the initial values. To ensure the accuracy of the tilt angle and displacement calculation, the calibration and verification test of the single MEMS sensor and sensor array is conducted. The MEMS accelerometer array is verified with respect to its principle and arrangement by a laboratory physical model test, and the initial experimentation demonstrated the capacities of the monitoring system for collecting real-time and in-situ information about the dynamic process and propagation of slope failure.

The 109 meridian fault is located in the west of the South China Sea (SCS) connecting to the offshore Red River Shear Zone. Seismic data from the central Vietnamese shelf indicates that many submarine landslides were developed along the steep continental slope in this offshore region. Here, we analyze the potential for such landslides to trigger damaging tsunamis based on the local geological background and sedimentary environment. We assess their tsunamigenic potential along the coast of Southern Central Vietnam (SCV). We point out that the evolutionary processes of the 109° meridian fault: striking-subsidence of the adjacent basin, combined with the high sediment input from numerous montane rivers of the hinterland generate conditions that likely favor the development of submarine landslides along the well-defined and steep continental slope near SCV. To estimate the impact of tsunami waves on the SCV coastline, we conducted a pilot study using two numerical models: NHWAVE and FUNWAVE-TVD to model 4 representative landslides with volumes ranging between 1.3 and 14 km3 and water depth of 300–1000 m. The submarine landslides were treated as rigid slump and deformable slide corresponding to two different sedimentary environments. Our results show that the tsunami waves generated by rigid slump can reach up to 20 m height in the landslide source area and ∼5 m when arriving at the closest coastline. Tsunami waves could arrive at the central Vietnam coast within 30 min in eight scenarios. Our initial results also suggest that seafloor topography, i.e., waveguide effects of ocean ridges, shelf resonance and the potential bay resonance cause significant variability in potential run-up. We note that ocean ridges located in the deep basin of the SCS focus the tsunami energy propagating towards the northwest coast of Luzon Island, Philippines where tsunami wave heights of ∼2.3 m wave height are modeled. These findings underscore the importance of tsunami hazard assessments that account for both earthquake generated and earthquake triggered tsunamis. Our work also highlights a continued need to examine tsunami sources in the region as mitigation and preparedness for the socio-economically important and heavily populated coastlines of the SCS is reliant on a detailed understanding of the hazard. Ministry of Education (MOE) Nanyang Technological University National Environmental Agency (NEA) National Research Foundation (NRF) Published version This work was supported by Guangdong Province Introduced Innovative R&D Team of Geological Processes and Natural Disasters around the South China Sea (2016ZT06N331), Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (No. 311021002), National Natural Science Foundation (No. 41976197) and Key Research and Development Program of Hainan Province (No. ZDYF2020209). Research by ADS is partially supported by the Singapore Ministry of Education Academic Research Fund MOE2019-T3-1-004 and MOE2018-T2-1-030, the National Research Foundation Singapore, the Singapore Ministry of Education under the Research Centers of Excellence initiative, and by the Nanyang Technological University. ADS and LL are also supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under the National Sea Level Programme Funding Initiative (Award No. USS-IF-2020-2). This work is granted by the Program for supporting scientific research activities for 1st rank senior researcher by Vietnam Academy of Science and Technology under grant number NCVCC12.03/22-22.

Dynamic sliding process of submarine slope is a hotspot issue in ocean geotechnical engineering. Due to the lack of the numerical simulation method which could describe the dynamic characteristics of the saturated soft clay under seismic loading, few researches are reported on the dynamic sliding process of submarine slope in saturated cohesive soil deposits. Adopting the subroutine interface technology provided by ABAQUS platform, the undrained cyclic elastoplastic constitutive model, which could describe the dynamic characteristics of saturated soft clay, is programmed into user-defined material subroutine VUMAT and embedded in display dynamics analysis module of ABAQUS platform. Based on the cyclic elastic-plastic constitutive model and the updated Lagrangian technology, a numerical simulation method is proposed to investigate the dynamic sliding process of submarine soft clay slope under seismic loading. The applicability of the proposed numerical simulation method is verified by comparing with the previous research results. The results show that the strain accumulation characteristic makes the final accumulated deformation and shear strain larger than that of the conventional numerical modeling methods. When the general static constitutive model is used for dynamic analysis of slope, the analysis results are not conservative because the strain accumulation characteristic cannot be considered. Besides, it can display the whole dynamic sliding process of the slope, more intuitively predict the slope topography before and after earthquake, which could provide a reference for the planning and design of offshore structures.

In the present study, three different types of landslide-generated tsunamis (subaerial, partially submerged and submarine) were investigated through laboratory experiments that used 261 different e...

In comparison to the east coast, the tsunami hazard for the west coast of India remains under-recognized, despite the impact in 1945 following a Mw 8.1 earthquake in the Makran subduction zone in the northern Arabian Sea. The previous occurrences of tsunamis in the Arabian Sea that would have a bearing on the west coast of India are being debated, including the question whether the Makran region has the potential to generate greater-magnitude earthquakes. With this in the backdrop, we present here the historical and geological evidence of a tsunami impact zone from a site on the Konkan Coast of western India. Located in the village of Kelshi, the impact zone is preserved within a coastal dune complex that also reveals occupation layers. This laterally extending 30–40-cm-thick zone, coinciding with a habitation level, displays varied sedimentary structures including scour-fill features, and is inter-layered with shells, at a height of ~ 3 m from the high-tide level. We attribute these sedimentary features to a tsunami flooding event that was contemporaneous with the transportation of shells, dated at 1508–1681 CE. The geological inference matches with the description by the Portuguese fleets of a sea disturbance in 1524 CE, reported from Dabhol, not far from Kelshi, and also from the Gulf of Cambay, located about 500 km to the north. Precluding submarine landslide scenarios, the modeling results suggest that the high impact in Kelshi could have been generated by a Mw ≥ 9 earthquake sourced in the Makran subduction zone. It is, however, intriguing how a Mw ≥ 9 earthquake in the Makran region finds no mention in the historical documentation. We underscore the need for fresh efforts along the Makran coast to reconstruct the tsunami recurrence history that would generate required validating constraints on the 1524 event, if it was indeed generated by a massive earthquake among other mechanisms.

International audience; Slope failure and landslides are widespread on the submarine slopes of carbonate platforms. They represent a key component of their stratigraphic evolution and a major geohazard. Several Quaternary slope failures and mass transport complexes were identified on the western slope and margin of the Great Bahama Bank (GBB) platform. This study evaluates several hypotheses for the preconditions associated to these events, in relation with the stratigraphic and environmental history of the platform. The forward stratigraphic simulator Dionisos Flow™ allows the slope stratigraphic evolution to be reconstructed on a 2D platform-to-basin section at high temporal resolution according to the eustatic and environmental history of the last 1.7 Myr. The hydromechanical simulator A2 is applied on this high-resolution stratigraphic grid for computing the mechanical stratigraphy of the section, that is the spatiotemporal pore pressure and stress state distribution. The simulated precondition of the platform margin during glacial lowstands results from the combination of two factors: transient overpressure generation by lateral fluid flow from the emerged platform and the steepening stratigraphic trend of the platform. No significant pore fluid overpressure is generated under high sedimentation rates or as a result of shift in hydrostatic gradient during sea-level falls. Precondition in the lower slope is not achieved in this 2D simulation, with the horizontal stress distribution counteracting the effect of overpressure build-up. It is found that cemented levels in the lower slope succession do not represent a significant preconditioning factor.

[Abstract Mixed siliciclastic‐carbonate deep‐marine systems (mixed systems) are less documented in the geological record than pure siliciclastic systems. The similarities and differences between these systems are, therefore, poorly understood. A well‐exposed Late Cretaceous mixed system on the northern side of the Eastern Greater Caucasus, Azerbaijan, provides an opportunity to study the interaction between contemporaneous siliciclastic and carbonate deep‐marine deposition. Facies analysis reveals a Cenomanian–early Turonian siliciclastic submarine channel complex that abruptly transitions into a Mid Turonian–Maastrichtian mixed lobe‐dominated succession. The channels are entrenched in lows on the palaeo‐seafloor but are absent 10 km towards the west where an Early Cretaceous submarine landslide complex acted as a topographic barrier to deposition. By the Campanian, this topography was largely healed allowing extensive deposition of the mixed lobe‐dominated succession. Evidence for irregular bathymetry is recorded by opposing palaeoflow indicators and frequent submarine landslides. The overall sequence is interpreted to represent the abrupt transition from Cenomanian–early Turonian siliciclastic progradation to c. Mid Turonian retrogradation, followed by a gradual return to progradation in the Santonian–Maastrichtian. The siliciclastic systems periodically punctuate a more widely extensive calcareous system from the Mid Turonian onwards, resulting in a mixed deep‐marine system. Mixed lobes differ from their siliciclastic counterparts in that they contain both siliciclastic and calcareous depositional elements making determining distal and proximal environments challenging using conventional terminology and complicate palaeogeographic interpretations. Modulation and remobilisation also occur between the two contemporaneous systems making stacking patterns difficult to decipher. The results provide insight into the behaviour of multiple contemporaneous deep‐marine fans, an aspect that is challenging to decipher in non‐mixed systems. The study area is comparable in terms of facies, architectures and the presence of widespread instability to offshore The Gambia, NW Africa, and could form a suitable analogue for mixed deep‐marine systems observed elsewhere., We use qualitative and quantitative sedimentology to document the evolution of a mixed siliciclastic‐carbonate deep‐marine system throughout the Cretaceous in the Eastern Central Graben, Azerbaijan. The system evolves from siliciclastic channel dominated to mixed lobe dominated, and interacts with mass failure topography throughout development. The interaction between the two contemporaneous systems make lobe stacking patterns difficult to decipher. ]

Exploring the submarine landslide is challenging due to the invisibility nature and the complex soil-water interaction and large deformation throughout its runout process. The purpose of this paper is to investigate the ability of the coupled material point method (MPM) in modeling the soil flows under water. A sand-column collapse experiment is performed fully under water initially, with the results used to benchmark the MPM analysis. Thereafter, the whole failure process of a real submarine landslide in the South Mediterranean sea is simulated using MPM. The results show that MPM can be a reliable tool in capturing the postfailure behaviors of the submarine landslide. The failure mode of the landslide is flow-type, with an initial translational slide moving to a diffusive one eventually.

Submarine landslides can cut off seabed pipelines and cables and destroy near-shore structures. Such processes can result in tsunamis, which inflict additional enormous damage in near-shore areas. To date, no modelling experiments have been able to simulate and clarify the conditions necessary for the occurrence of submarine landslides, their gravity flow transition and sedimentation. This study examined the submarine landslide of sand and silty sand induced by earthquake and liquefaction. First, similitude laws pertaining to a submarine landslide in a centrifuge were considered, and the conditions to produce a landslide in a centrifuge were investigated by using various types of test cases. The key factors were the combination of natural water and sand mixed with a significant fine fraction, including the osmotic pressure. In addition to these, the embankment slope failure followed by gravity flow, transition to flow, properties of flow and water-level fluctuation induced by ground failure were examined in detail. The debris flowed not with simple shear, but as a clod of soil similar to fluid, which encourages high-speed flow. Turbidity could be observed above the debris front body, and the fine fraction was deposited on the surface of the debris. The embankment slope failure induced water-level fluctuation.

Physical modelling studies of submarine landslides in a 5° slope were conducted to assess the occurrence of hydroplaning and turbidity currents. The centrifuge modelling did not aim to simulate the complete mudflow mechanism, but rather focused on assessing the hydroplaning and the turbidity current conditions. Four tests were performed using kaolin clay in a drum centrifuge (N = 40). The initial water content of the slurry and the pressure associated with the release of the mixture inside the centrifuge were varied during the tests in order to simulate different flow rates. The test results were evaluated by means of pore pressure and total stress measurements at the mudflow−slope interface in order to identify the flow conditions in which hydroplaning takes place. Froude and Reynolds numbers were also used to identify the turbidity current and hydroplaning phenomena. The particle image velocimetry technique was used to obtain the velocity field in order to complement the analysis.

Submarine landslides are a common type of disaster which threaten property and the safety of human life. To effectively prevent and control such disasters, we conduct a series of large-scale physical model tests to determine the mechanism of submarine landslides. First, a large-scale physical model test system is designed and developed, including flume test frame, wave-making system, wave-absorbing system, and data monitoring system. In the tests, we investigate the effect of different sea waves by changing the parameters of the wave-making system and the influence of the slope inclination by constructing different models. Data regarding the wave pressure acting on the slope surface, seepage pressure, and displacement are monitored during the test procedure. The test results show that the seepage pressure in the faults varies cyclically with the sea waves and is lower at internal points than at outcrops. If the wave loading time is sufficiently long, the seepage pressure and displacement deformation in the fault zone will gradually increase. In other words, failures in fault zones precede submarine landslides. The weak fault zone provides the preferred sliding surface, and the sea waves supply the external dynamic energy for submarine landslides. The conclusions provide guidelines for similar engineering and research.

Submarine sediment failures or landslides triggered by storm waves in river delta areas pose a significant risk to coastal infrastructure. Due to the limitations of in situ monitoring technology, existing investigations are mostly carried out with geophysical techniques to provide some basic characteristics (e.g. location, size, runout distance, volume, and potential triggers) of existing submarine landslides. However, it is of equal importance to identify the starting criterion and the in situ evolutionary process of the initial stage of seafloor instabilities—sediment failure, which naturally relies heavily on long-term field observations. A field monitoring system was developed for observing sediment failure, which successfully recorded the wave-induced seabed deformation in the subaqueous Yellow River Delta for the first time. Once sediment failure is initiated, the shallow soil undergoes periodic and reciprocating oscillations under alternating action of wave crests and troughs. The evolution of the maximum deformation depth interface moves from shallow to deep, and then migrates upward from deep to shallow layers (the shallow-deep-shallow pattern), which indicates a stability recovery process following the wave-induced seabed failure, and these processes were found to occur multiple times within one storm event. Laboratory wave flume experimental results reproduced and verified the field observations, while also providing pore pressure data which explains the initiation of sediment failure and the deformation process. Finally, a development pattern of the seafloor instabilities in the subaqueous Yellow River Delta is proposed. The in situ observation methods proposed and the knowledge acquired by field monitoring and flume testing could benefit the investigation of costal seafloor instabilities.

Submarine landslides have affected the mid-Norwegian margin since the Last Glacial Maximum. However, the role of tectonic movements, and most especially fault reactivation, in generating landslides offshore Norway is largely unconstrained. This study uses high-quality three-dimensional seismic and borehole data to understand how landslide development is controlled by faults propagating within the uplifted south Modgunn arch. Variance and structural maps above the south Modgunn arch show that: (1) local scarps of recurrent landslides were formed close to the largest faults, and mainly above strike-slip faults; (2) distinct periods of fault generation were associated with tectonic events, such as the breakup of the northeast Atlantic Ocean, and those events forming the south Modgunn arch; and (3) important fluid-flow features coincide with faults and sill intrusions. In total, 177 faults were analyzed to demonstrate that fault throw values vary from 10 ms to 115 ms two-way traveltime (8 m to 92 m). We propose that the long-term activity of faults in the study area has contributed to fluid migration, weakened post-breakup strata, and controlled the development of submarine slope instability. In particular, strike-slip faults coincide with the locations of several Quaternary landslide scars near the modern seafloor. Similar processes to those documented in Norway may explain the onset of large-scale landslides on other continental margins.

The published version of this article, unfortunately, contained error. Figure 3 of “GPU-hosted workstation for parallel computing” was lost. Then the sequences of the Figures 4-10 were wrong. Given in this article are the correct figures.

A graphical compilation of the 12 profiles analysed.

Submarine landslides are common at glaciated continental margins. The onset of large-scale landslides coincides with the initiation of Northern Hemisphere glaciations in the Quaternary. This implies that processes related to glacial cycling provide favourable conditions for submarine landslides at high-latitude margins. Potential processes include glacial deposition patterns and enhanced seismicity. It is also possible that advances and retreats of ice sheets, a highly dynamic process in geologic terms, makes slopes discernible to failure by modifying the stress regime. Here, we quantify this effect using 2D Finite Element modelling of a glaciated continental margin. Different model runs investigate the pore pressure development in homogeneous as well as layered slopes during glaciation when loaded by an ice stream with one or multiple ice advances. Ice streams cause significant variations in excess pore pressure in the very shallow sediment sequences at the continental shelf. However, lateral fluid flow is not efficient enough to increase pore pressures significantly at the slope, where large-scale submarine slides are observed. Hence, while ice sheet dynamics appear to favour the occurrence of shallow slides close to the shelf edge, ice sheets seem to be irrelevant for the generation of large-scale submarine landslides at the continental slope.

Tsunami present a significant geohazard to coastal and water-body marginal communities worldwide. Tsunami, a Japanese word, describes a series of waves that, once generated, travel across open water with exceptionally long wavelengths and with very high velocities before shortening and slowing on arrival at a coastal zone. Upon reaching land, these waves can have a devastating effect on the people and infrastructure in those environments. With over 12 000 km of coastline, the British Isles is vulnerable to the tsunami hazard. A significant number of potential tsunami source areas are present around the entire landmass, from plate tectonic boundaries off the Iberian Peninsula to the major submarine landslides in the northern North Sea to more localized coastal cliff instability which again has the potential to generate a tsunami. Tsunami can be generated through a variety of mechanisms including the sudden displacement of the sea floor in a seismic event as well as submarine and onshore landslides displacing a mass of water. This review presents those impacts together with a summary of tsunami triggers and UK case histories from the known historic catalogue. Currently, apart from some very sensitive installations, there is very little in the UK in the way of tsunami management and mitigation strategies. A situation that should be urgently addressed both on a local and national level.

This work was completed as part of a Scottish Funding Council (SFC) Global Challenges Research Fund (GCRF) pump-priming project at Heriot Watt University (PI Nicholson). We would like to thank our partners at Bandung Institute of Technology, and the members of the Indonesian Marine Geological Institute and Geological Survey of Indonesia for their discussion and contribution to this research. We thank TGS and Multiclient Geophysical for permission to publish seismic and multibeam data respectively. D.R. Tappin publishes with the permission of the Executive Director of the BGS (United Kingdom Research and Innovation).

Contourite drifts are sediment deposits formed by ocean bottom currents on continental slopes worldwide. Although it has become increasingly apparent that contourites are often prone to slope failure, the physical controls on slope instability remain unclear. This study presents high-resolution sedimentological, geochemical and geotechnical analyses of sediments to better understand the physical controls on slope failure that occurred within a sheeted contourite drift within the Faroe–Shetland Channel. We aim to identify and characterize the failure plane of the late Quaternary landslide (the AFEN Slide), and explain its location within the sheeted drift stratigraphy. The analyses reveal abrupt lithological contrasts characterized by distinct changes in physical, geochemical and geotechnical properties. Our findings indicate that the AFEN Slide likely initiated along a distinct lithological interface, between overlying sandy contouritic sediments and softer underlying mud-rich sediments. These lithological contrasts are interpreted to relate to climatically controlled variations in sediment input and bottom current intensity. Similar lithological contrasts are likely to be common within contourite drifts at many other oceanic gateways worldwide; hence our findings are likely to apply more widely. As we demonstrate here, recognition of such contrasts requires multi-disciplinary data over the depth range of stratigraphy that is potentially prone to slope failure.

Submarine landslides occur on continental margins globally and can have devastating consequences for marine habitats, offshore infrastructure and coastal communities due to potential tsunamigenic consequences. Evaluation of the magnitude and distribution of submarine landslides is central to marine and coastal hazard planning. Despite this, there are few studies that comprehensively quantify the occurrence of submarine landslides on a margin-wide scale. We present the first margin-wide submarine landslide database along the eastern margin of New Zealand comprising >2200 landslide scars and associated mass-transport deposits. Analysis of submarine landslide distribution reveals 1) locations prone to mass-failure, 2) spatial patterns of landslide scale and occurrence, and 3) the potential preconditioning factors and triggers of mass wasting across different geologic settings. Submarine landslides are widespread on the eastern margin of New Zealand, occurring in water depths from ~300 m to ~4,000 m. Landslide scars and mass transport deposits are more prevalent, and on average larger, on the active margin, compared the passive margin. We attribute higher concentrations of landslides on the active margin to the prevalence of deforming thrust ridges, related to active margin processes including oversteepening, faulting and seamount subduction. Higher sediment supply on the northernmost active margin is also likely to be a key preconditioning factor resulting in the concentration of large landslides in this region. In general, submarine landslide scars are concentrated around canyon systems and close to canyon thalwegs. This suggests that not only does mass wasting play a major role in canyon evolution, but also that slope undercutting in canyons may be a fundamental preconditioning factor for slope failure. Results of this study offer unique insights into the spatial distribution, magnitude and morphology of submarine landslides across different geologic settings, providing a better understanding of the causative factors for mass wasting in New Zealand and around the world.

The impact forces of submarine landslides (i.e., non-Newtonian fluids) on oil and gas pipelines, especially the most dangerous drag force, are of great significance in the design of deep-w...

The aim of this study is to develop an efficient numerical scheme that is capable of simulating landslide-generated waves. The numerical scheme is based on the one-layer non-hydrostatic (NH-1L) model, a phase-solving model that can account for weakly dispersive waves. In this paper, the model is extended to include a time-varying solid bed. This NH-1L scheme is very efficient because, at each time step, only a tridiagonal Poisson pressure matrix needs to be solved. In this study, the capability of the NH-1L scheme to simulate landslide-generated waves is demonstrated by executing two types of landslide motion: constant speed and with acceleration and deceleration. Validation was performed using analytical solutions of the linear weakly dispersive (LWD) model, as well as experimental data. The NH-1L model was capable of describing the generation and propagation of water waves by a submarine landslide from relatively intermediate water to shallow water depths.

We present an analysis of the oldest detailed account of tsunami run-up in Indonesia, that of the 1674 Ambon tsunami (Rumphius in Waerachtigh Verhael van de Schuckelijcke Aerdbebinge, BATAVIA, Dutch East Indies, 1675). At 100 m this is the largest run-up height ever documented in Indonesia, and with over 2300 fatalities even in 1674, it ranks as one of Indonesia’s most deadly tsunami disasters. We consider the plausible sources of earthquakes near Ambon that could generate a large, destructive tsunami, including the Seram Megathrust, the South Seram Thrust, and faults local to Ambon. We conclude that the only explanation for the extreme run-up observed on the north coast of Amon is a tsunami generated by an earthquake-triggered coastal landslide. We use a two-layer tsunami model to show that a submarine landslide, with an approximate volume of 1 km3, offshore the area on Ambon’s northern coast, between Seith and Hila, where dramatic changes in coastal landscape were observed can explain the observed tsunami run-up along the coast. Thus, the 1674 Ambon tsunami adds weight to the evidence from recent tsunamis, including the 1992 Flores, 2018 Palu and Sunda Strait tsunamis, that landslides are an important source of tsunami hazard in Indonesia.

The tsunami hazard for the Maltese Islands is poorly defined, and historic records are available for only two recent events. Most of the population and touristic infrastructure of the archipelago is concentrated along the eastern low-lying coastline, which is exposed to tsunamis from near-field and far-field sources. In this study we present a scenario-based tsunami inundation study to assess the impact of potential significant cases. We simulated four scenarios—two submarine landslide sources (outer Malta Plateau slide and Gela Basin slide) and two earthquake sources mimicking events comparable to the 365 A.D. western Hellenic Arc event and the 1693 south-east of Sicily event. We find that all scenarios cause inundation in densely populated low-lying bays or rias of Mellieha Bay, Xemxija, Salini, Gzira, Msida, Marsaskala, St Thomas Bay, Marsaxlokk and Birzebbuga. The largest inundation extents and flow depths (> 10 m) are produced by the two landslide sources and the western Hellenic Arc earthquake. Of interest is the role of the Malta Escarpment and Sicily in amplifying and reflecting tsunami waves, and in generating consistent hot spots along the eastern coastline of Malta.

Tsunamis are one of the most catastrophic natural hazards that can devastate coastal regions. Most common mechanisms that generate tsunamis are undersea earthquakes and submarine landslides. However, in enclosed basins, such as fjords, reservoirs, and lakes, subaerial landslides can also generate devastating tsunamis with similar or worse consequences, because of a more efficient wave generation. Here, we present the validation of a three-dimensional (3D) numerical model, TSUNAMI3D, by comparing numerical results with a set of subaerial landslide laboratory experiments carried out in the large tsunami wave basin at the Oregon State University (OSU). Results obtained from the laboratory experiments show that subaerial landslides generate highly non-linear waves with complex wave patterns and runup, challenging existing numerical models. The 3D numerical model is first verified with a commercial code, FLOW3D, to obtain a compromise between the model’s spatial-time resolution accuracy and computational cost. Second, the 3D numerical model and the commercial code are validated with a set of OSU laboratory experiments comprising three different layouts or basin configurations, namely, fjord, curved headland, and basin-wide. Simplified material rheology and key parameters required for modeling subaerial landslides are defined. Numerical models’ relative errors are estimated and analyzed, and the models’ limitations are discussed. In general, numerical models’ relative errors are found to be acceptable in most of the validation tests except those tests located close to the wave generation region. Validation results confirm that the 3D numerical models with simplified landslide rheology can be used to understand and reproduce the complex non-linear wave propagation and runup generated by subaerial landslides. Thus, TSUNAMI3D can help assess tsunami hazards in communities located in proximity to potential subaerial landslides. Also, the set of physical experiments can be used for further numerical validation efforts, helping tsunami organizations, e.g., the National Tsunami Hazard Mitigation Program, to amend existing or develop better numerical models and thus, improve inundation/evacuation mapping products that would save lives and property.

Gigantic submarine landslides pose a significant threat to offshore infrastructures and may be initiated by an inconspicuous weakened zone, followed by catastrophic shear band propagation under the effect of strain softening. Much attention has been paid over the last two decades to unidirectional (parallel to the travel direction of sliding mass) shear band propagation (SBP) related exclusively to an initiation zone that is wide relative to the SBP direction. The paper investigates for the first time the mechanisms of more realistic planar shear band propagation via numerical modelling including finite element and finite difference analyses. Rather than propagating only along the travel direction for a 1D shear band in a plane-strain slope, the multidirectional propagation behaviour of a planar shear band depends significantly on the aspect ratio of the initiation zone. New criteria for catastrophic propagation of a planar shear band are proposed and are shown to be in good agreement with the numerical results. The criteria with respect to the initiation zone area can be incorporated easily within a GIS-based stability analysis of catastrophic submarine landslides, facilitating robust hazard analysis for offshore developments.

Submarine landslides (slides) are some of the most voluminous sediment gravity-flows on Earth and they dominate the stratigraphic record of many subaqueous basins. The general kinematics and internal structure of slides are relatively well-understood, although the way in which they increase in volume and internally deformed as they evolve, and how these processes relate to the development of their basal (shear) surface, remains largely unknown. We here use three high-resolution 3D seismic surveys (two broadband time-migrated seismic reflection datasets and a depth-migrated volume) from the Angoche Basin, offshore Mozambique to undertake detailed mapping and intra-slide strain analysis of a shallowly buried, large, and thus well-imaged submarine landslide (c. 530 km3). We also provide detailed documentation of the along-strike variations in the structural style and evolution of the toe region, and how these relate to the overall emplacement of the slide. Seismic attribute analysis image several key kinematic indicators, including broadly NW-trending (i.e., flow-parallel) lateral margins, longitudinal shears, and sub-orthogonal shears in the main body of the deposit, and broadly NE-trending (i.e., flow-normal) symmetric pop-up blocks in the toe region. The slide exhibits varying degrees of frontal emergence along strike, displaying a single frontal (toe) wall in the SW to a more complex, stair-step geometry in the NE. Basal grooves are noticeably absent, with a key observation being that contractional structures are locally observed c. 7 km downdip of the present toe wall. Based on the distribution of and cross-cutting relationship between intra-slide structures, we propose an emplacement model involving two distinct phases of deformation; (i) bulk shortening, parallel to the overall SE-directed emplacement direction, accommodated by the formation of NE-trending symmetric pop-up blocks bound by fore-thrusts and back-thrusts; and (ii) the development of NW-trending sinistral shear zones that offsets the earlier formed shortening structures, and which possibly formed due a spatial variations the evolving rock strength as the flow arrested, resulting in intra-slide flow cells. We infer the basal shear surface or zone incrementally propagated downdip ahead of the developing slide mass, with distal contractional structures being the expression of rather cryptic, updip sliding of the entire sediment mass. Our study demonstrates the value of using 3D seismic reflection data to study the structure and emplacement kinematics of slides, and the complex strains that can arise due to temporal and spatial variations in sediment rheology.

Submarine landslides can generate complicated patterns of seafloor relief that influence subsequent flow behaviour and sediment dispersal patterns. In subsurface studies, the term mass transport deposits (MTDs) is commonly used and covers a range of processes and resultant deposits. While the large-scale morphology of submarine landslide deposits can be resolved in seismic reflection data, the nature of their upper surface and its impact on both facies distributions and stratal architecture of overlying deposits is rarely resolvable. However, field-based studies often allow a more detailed characterisation of the deposit. The early post-rift Middle Jurassic deep-water succession of the Los Molles Formation is exceptionally well-exposed along a dip-orientated WSW-ENE outcrop belt in the Chacay Melehue depocentre, Neuquén Basin, Argentina. We correlate 27 sedimentary logs constrained by marker beds to document the sedimentology and architecture of a >47 m thick and at least 9.6 km long debrite, which contains two different types of megaclasts. The debrite overlies ramps and steps, indicating erosion and substrate entrainment. Two distinct sandstone-dominated units overlie the debrite. The lower sandstone unit is characterised by: 1) abrupt thickness changes, wedging and progressive rotation of laminae in sandstone beds associated with growth strata; and 2) detached sandstone load balls within the underlying debrite. The combination of these features suggests syn-sedimentary foundering processes due to density instabilities at the top of the fluid-saturated mud-rich debrite. The debrite relief controlled the spatial distribution of foundered sandstones. The upper sandstone unit is characterised by thin-bedded deposits, locally overlain by medium-to thick-bedded lobe axis/off-axis deposits. The thin-beds show local thinning and onlapping onto the debrite, where it develops its highest relief. Facies distributions and stacking patterns record the progradation of submarine lobes and their complex interaction with long-lived debrite-related topography. The emplacement of a kilometre-scale debrite in an otherwise mud-rich basinal setting and accumulation of overlying sand-rich deposits suggests a genetic link between the mass-wasting event and transient coarse clastic sediment supply to an otherwise sand-starved part of the basin. Therefore, submarine landslides demonstrably impact the routing and behaviour of subsequent sediment gravity flows, which must be considered when predicting facies distributions and palaeoenvironments above MTDs in subsurface datasets. Fil: Martínez Doñate, A.. University of Manchester; Reino Unido Fil: Privat, A.M.L.J.. University of Leeds; Reino Unido Fil: Hodgson, D.M.. University of Leeds; Reino Unido Fil: Jackson, C.A.L.. Imperial College London; Reino Unido Fil: Kane, I.A.. University of Manchester; Reino Unido Fil: Spychala, Y.T.. Leibniz Universitat Hannover; Alemania Fil: Duller, R.A.. University of Liverpool; Reino Unido Fil: Stevenson, C.. University of Liverpool; Reino Unido Fil: Keavney, E.. University of Leeds; Reino Unido Fil: Schwarz, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Flint, S.S.. University of Manchester; Reino Unido

Small landslides in the upper submarine slopes of volcanic islands present potential hazards locally because of their high frequency. We examine evidence for landsliding in high-resolution bathymetric data from Faial, Pico, São Jorge and Terceira islands of the Azores. Because the rugged morphology of the upper slopes makes landslides difficult to interpret, we develop two classification schemes for the 1227 identified slope valleys. One scheme addresses how recognizable the valleys were as originating from landslides (whether scarps are prominent or indefinite), whereas the other scheme addresses valley types (whether apparently produced by single or multiple failures). Size distributions are used to assess the relative occurrence of large versus small landslides. Thirteen landslides are predicted to have generated tsunami heights at source of >1 m and one with height of >7 m. Some slopes have gradients far above 30˚, the angle of repose of incohesive clastic sediment, so the seabed in those areas is strengthened perhaps by carbonate cementation, by seismic shaking or by the presence of coherent lava or lava talus. Using all types of slope valleys, Faial and Pico have smaller affected volumes per unit slope area than those of São Jorge and Terceira. These differences could be associated with varied seismic activity, with more frequent earthquakes beneath Faial and Pico preventing the build-up of sediments on their slopes. Submarine landslide statistics are therefore potentially useful for assessing long-term earthquake hazards of volcanic islands in seismically active environments such as the Azores.

The volume of a submarine landslide is likely to be amplified by shear band propagation along a basal surface or spreading failure extension in the sliding layer. Although the mechanism of translational submarine landslides has been understood using the interpretation of shear band propagation, assessment of the limits of failure extension, either through shear band propagation or retrogressive spreading, remains a challenge due to the diversity of post failure mechanisms. The paper aims to explore all post failure possibilities and quantify failure initiation and extension accordingly, focusing on the upslope conditions. The different failure mechanisms are explored with the aid of the large deformation finite element modeling. Original criteria for scarp position, shear band length at slab failure, retrogression conditions and ultimate spreading limits are proposed, following the process zone approach considering force equilibrium of the sliding mass. Simplified analytical predictions are shown to agree well with the numerical observations. The findings and criteria presented in the study are expected to help assess the ultimate scale of upslope failure in submarine landslides, which is important in determining geohazard zonation of submarine landslides., Journal of Geophysical Research: Solid Earth, 126 (9), ISSN:2169-9313, ISSN:0148-0227, ISSN:2169-9356

A submarine landslide is a well-known geohazard that can cause significant damage to offshore engineering facilities. Most standard predicting and mapping methods require expert knowledge, supervision, and fieldwork. In this research, the main objective was to analyze the potential of unsupervised machine learning methods and compare the performance of three different unsupervised machine learning models (k-means, spectral clustering, and hierarchical clustering) in modeling the susceptibility of the submarine landslide. Nine groups of geological factors were selected as the input parameters, which were obtained through field surveys. To estimate submarine landslide susceptibility, all input factors were separated into three or four groups based on data features and environmental variables. Finally, the goodness-of-fit and accuracy of models were validated with both internal metrics (Calinski–Harabasz index, silhouette index, and Davies–Bouldin index) and external metrics (existing landslide distribution, hydrodynamic distribution, and liquefication distribution). The findings of k-means, spectral clustering, and hierarchical clustering performed commendably and accurately in forecasting the submarine landslide susceptibility. Spectral clustering has the greatest congruence with environmental geology parameters. Therefore, the unsupervised machine learning model can be used in submarine-landslide-predicting studies, and the spectral clustering method performed best. Furthermore, machine learning can improve submarine landslide mapping in the future with the development of models and the extension of geological data related to submarine landslides.