Slide Plane Research Articles

Landslide Identification on Tembalang-Jangli New Road, Semarang, Central Java Using Dipole-Dipole Configuration Resistivity Geoelectric Method

New roads are built to alleviate congestion that occurs in an area. Tembalang is one of the most densely populated areas in Semarang city. The research location is Tembalang-Jangli New Road. The construction of Jangli-Undip New Road aims to reduce congested vehicle traffic in Gombel and Meteseh, which causes frequent congestion. Therefore, subsurface identification using the resistivity geoelectric method of dipole-dipole configuration was carried out to know the cause of landslides at the research location. Data acquisition was carried out with 10 passes. The results obtained 5 (five) layers of subsurface constituent rocks on Undip-Jangli New Road based on their resistivity values, namely topsoil (0.105 - 1.0 Ωm), clay (1.11 - 6.29 Ωm), sandstone (8.52 - 20.0 Ωm), tuff (20.0 - 75.0 Ωm), and volcanic breccia (75.0 - 133 Ωm). The interpretation results show the sliding plane at a 6.76 - 24.8 m depth. The layer that acts as a slide plane is a clay layer. The existence of sliding planes detected in the trajectories A-A’, B-B’, C-C‘, D-D’, E-E‘, F-F’, G-G‘, H-H’, I-I‘, and J-J’ has great potential to cause soil movement or landslides with the type of sliding is rotation. Keywords: landslide, resistivity geoelectricity, dipole-dipole.

Berthierine authigenesis as grain pseudomorph? A new insight from the early Maastrichtian Kallankurichchi Formation, India

This study presents detailed sedimentological, geochemical, and mineralogical evidence of green clay formation at the basal part of the early Maastrichtian Kallankurichchi Formation, Cauvery Basin, India. Immediately overlying a basal scree conglomerate, the highly fossiliferous Kallankurichchi Formation hosted a ∼ 3.5 m thick dark grey limestone containing abundant green clay minerals formed by the alteration of metastable framework grains. Abundant fresh to partially palagonitized sideromelane glass and occasional preservation of gas bubble structures in green clays strongly suggest a volcaniclastic source. Petrographic observations manifested primary occurrences of the green grain pseudomorphs mimicking the shape of the precursor volcanic grains. The X-Ray Diffraction analysis of the randomly oriented bulk sample and oriented, smear-mounted green clay separates identified the berthierine by the strong ∼7 Å basal spacing. The mineral chemical data of the berthierine grain pseudomorphs recorded substantial compositional variation from Mg-, Si- and Al-rich core and Fe-rich rim, characterizing the maturation of berthierine from volcaniclastic substrate through ‘proto’-berthierine. Tiny berthierine flakes (1–5 μm long) grew vertically from the mineral grain boundary and feldspar cleavages, suggesting its authigenic origin. Contemporaneous tectonic events, marked by abundant slide planes, suggested continuous sagging of the basin, causing oxygen-depleted bottom water conditions. The unusual appearance of berthierine as grain pseudomorphs, rarely reported from the rock record, revealed the dissolution of metastable volcaniclastic grains in a slightly acidic, oxygen-depleted depositional environment as the primary mechanism of authigenesis. The early diagenetic calcite cementation ceased the berthierine formation, preventing compaction and transformation.

Reconstruction of Natural Slope Stability by Limit Equilibrium Methods and Finite Element Methods

Slope stability analysis is particularly important for natural slopes that are relatively undesigned to be technically safe. Natural slopes are prone to collapse depending on the condition of the slope material and rainfall. A comprehensive stability analysis using numerical methods to calculate the factor of safety and probability of collapse can be used as a reference to assess the safety of a slope. This study discusses boundary equilibrium and finite element in the analysis of slope safety factor and landslide probability by reconstructing the slope with landslide history. The reconstruction of the slope is based on the actual slope condition with saturated material due to rain that has a safety factor of 0.5 using mathematical methods which are then analyzed numerically in this study. The results of the factor of safety on the saturated condition slope have a value that is not much different from the actual condition with a 100% probability of landslide. The results of low shear strength values in each slice of the limit equilibrium analysis for saturated conditions also indicate that the slope is in an unsafe condition which is supported by the development of shear and tensile strains in the finite element method analysis in the slope slide plane area which causes the stress distribution in the actual landslide area to be unstable.

Submarine landslides on the Eastern South Korea Plateau (ESKP)—Do pumice-rich tephra layers control slope stability?

Tephra layers embedded in marine sediments can be significant in controlling submarine landslide dynamics and seafloor morphology, but their preconditioning effects on slope failure remain uncertain. Here, we study the morphology and preconditioning factors of submarine landslides from a volcanically active region, the Eastern South Korea Plateau (ESKP) using a recently acquired multibeam echosounder (MBES), high-resolution sub-bottom chirp profiler, and piston core data, together with previous geophysical data. At least 50 translational landslides were identified on the southern margin of the ESKP in an area of ∼470 km2, with a relatively small volume of remobilized sediment (∼10 km3). The landslide headscarps are arcuate, up to 400 m in height, and lie at water depths of 980 to 2300 m. Landslides on the upper ESKP margin are more disintegrative (debris flow type) than those on the lower margin which consists largely of blocky type failures with small runouts. Landslide deposits identified in the cores consist of debris flows and slides/slumps while background deposits contain hemipelagic mud interbedded with ca. 10-cm-thick coarse-grained, poorly-sorted pumiceous tephra. Seismic and core integration indicate that the glide planes of the observed slides correspond to the pumice-rich tephra layers. These tephras are predominantly composed of fresh volcanic glass devoid of clay, indicating that the composition of the tephra did not control the formation of weak layers or slide planes. We infer therefore that the weakness of the glide planes resulted from high hydraulic (pore) pressure at the interface between some of the porous tephra layers and their overlying, relatively impermeable, hemipelagic mud. In addition to burial compaction and build-up of pore pressure in the tephra layers, fluid overpressure could have been facilitated by earthquakes causing granular convection within, and compaction of, the poorly sorted tephra. The landslide predominantly formed > ca. 84 ka ago, which suggests time-restricted triggering associated with a temporary increase in seismicity and/or sediments reaching their overpressure threshold during burial compaction. Our study suggests that regional occurrences of discrete layers of porous tephra deposits within finer grained hemipelagic sediments can potentially control the generation of landslides in subaqueous environments affected by explosive volcanism.

Shallow marine glauconitization during the Proterozoic in response to intrabasinal tectonics: A study from the Proterozoic Lower Bhander Sandstone, Central India

Glauconite forms authigenically by the replacement of quartz and feldspar substrates within the Precambrian Lower Bhander Sandstone (LBS) of the Vindhyan Basin. The glauconite exhibits consistently high K2O (7.08–8.62 wt%) and low to moderate TFe2O3 (6.20–18.5 wt%). The X-Ray Diffraction study reveals an evolved to highly evolved glauconitic mica structure. The deposition of mudstone-dominated LBS took place in a shallow marginal marine environment within a low gradient epeiric sea. The overall fining upward succession of the LBS comprises multi-storied, meter scale progradational cycles defined by red mudstone and sandstone–siltstone alternation in ascending order. The repetitive cycles indicate recurrent low-magnitude basin subsidence of the epeiric seafloor. Slump folds and slide planes, associated with the wedge-shaped mud pebble conglomerate, mark each episodes of basin subsidence. The glauconite occurs within sandstone and the sandy matrix of a wedge-shaped conglomerate at the base of a shallowing upward cycle which starts with a grey colored mudstone. The enrichment factors of redox-sensitive elements elucidate sub-oxic depositional condition during the glauconitization. The redox-sensitive element ratios (V/Cr, V/Sc) corroborates the sub-oxic depositional condition for the glauconitic interval and oxic environment for the encasing sediments. The formation of glauconite in the LBS corresponds to the deepening of the basin in response to the tectonic subsidence. The meter scale progradational cycles, recording the transition from suboxic to oxic conditions, corresponds to tectonically-induced deepening and subsequent filling. This study recognizes the significance of intrabasinal tectonics in facilitating suitable redox conditions for the glauconitization process within Proterozoic shallow epeiric sea deposit.

Automatic numerical focus plane estimation in digital holographic microscopy using calibration beads.

We present a new method to achieve autofocus in digital holographic microscopy. The method is based on inserting calibrated objects into a sample placed on a slide. Reconstructing a hologram using the inverse problems approach makes it possible to precisely locate and measure the inserted objects and thereby derive the slide plane location. Numerical focusing can then be performed in a plane at any chosen distance from the slide plane of the sample in a reproducible manner and independently of the diversity of the objects in the sample.

Modeling of growth rate and morphology mechanism of whisker and hillock on micro-bumps under temperature-pressure-humidity storage

A novel model was established to calculate growth rate of whisker and illustrate the morphology mechanism of whisker on fine-pitch Cu pillar micro-bumps under temperature-pressure-humidity storage. Growth of tin whisker and hillock underwent incubation period, quick growth and final steady growth. Theoretical steady-state average growth rate of whisker on micro-bumps calculated by our model were much more accurate than the previous models in order of magnitude. Besides, the diversification of morphologies of tin whisker and hillock were dependent on the synergetic effect of JL, JR, slide plane rotation, grain boundary migration and intermetallic compounds particles pinning. The findings are of great significance to the study of tin whisker and hillock on isolated Sn-based solders and provide insights into the reliability of advanced packaging.

A Dynamic Method to Predict the Earthquake-Triggered Sliding Displacement of Slopes

The earthquake-induced permanent displacement is an important index of the potential damage to a slope during an earthquake. The Newmark method assumes that a slope is a rigid-plastic body, and the seismic responses of sliding masses or seismic forces along the slide plane are ignored. The decoupled method considers no relative displacement across the sliding plane, so it overpredicts the seismic response of the sliding mass. Both dynamic and sliding analyses are performed in the coupled method, but when Ts/Tm is large, the results are unconservative. In this paper, a method is proposed to predict the earthquake-triggered sliding displacement of slopes. The proposed method is based on the Newmark rigid method, coupled method, and decoupled method considering both the forces at the sliding interface and the system dynamics under critical conditions. For the flexible system, the displacements are calculated with different stiffness values, and the results show that as the stiffness increases and tends to infinity, the critical acceleration and displacements of the proposed method are close to those of the Newmark method. The proposed method is also compared with the Newmark method with the period ratio Ts/Tm. At small values of Ts/Tm, the flexible system analysis results of the displacement are more conservative than those of the rigid block model; at larger values of Ts/Tm, the rigid block model is more conservative than the flexible system.

Seafloor breathing helping forecast hydrate-related geohazards

Gas hydrate dissociation may pose serious geohazards. The response of the seafloor to hydrate dissociation is important for geohazards, marine environments and global climate. We studied how hydrate dissociation affects underground temperature and pressure and how dissociation may lead to seafloor deformation. Here, we designed a laboratory model experiment to visualize fluid migration and seafloor deformation during hydrate dissociation at atmospheric pressure. Our experiments show visible gas pipes, migratory gas and gas pockets due to hydrate dissociation and explain the newly discovered discordance between the slide plane and the base of the gas hydrate stability zone. We found that the underlying free gas and gas conduits not only are favorable factors for forming hydrates but also can be promoted by hydrate dissociation. The temperature, pressure, and seafloor deformation are collected during the experiments. Our results show that the hydrate dissociation process is an endothermic reaction. More importantly, hydrate dissociation-induced overpressure exhibits a sudden decrease after slow growth and this inflation–deflation cycle resembles breathing. In our experiments, seafloor deformation are dominated by underground overpressure and lags up to about ten minutes. This deformation pattern could help forecast seafloor subsidence based on deformation observations. Overpressure monitoring is effective and saves time to cope with imminent geohazards. This pattern is important for geologists and engineers to forecast hydrate-related geohazards.

Laboratory experiments with self-cohesive powders: Application to the morphology of regolith on small asteroids

A series of experiments have been conducted to study the failure behavior of columns and piles comprised of cohesive fine powders in 1 ​g as a proxy for those which might occur in the agglomerated asteroid structure composed of cm-m size pebbles and boulders in a microgravity environment. Initially symmetrical piles of fine powders, under gravitation or centrifugal stress, develop features similar to those observed on asteroids, such as slide planes and finer cohesive structures. Failure of cohesive columns of fine powders occurs by the nucleation and propagation of fracture planes. In some cases, forming steep cliffs, also reminiscent of features observed on asteroids. Correlation between observed column failure and numerical simulations has been demonstrated based on preliminary results. Microstructure and particle size distribution are shown to substantially determine the extent of cohesiveness. Enhanced cohesion was observed for specific ratios of larger particle intermixed with fine powders. We propose that the wide range of qualitative features and behaviors may reasonably represent those observed on asteroid features as the surface ages. This work has important implications for our understanding and preparation for future missions to NEOs.

The Setting of Strength Parameters in Stability Analysis of Open-Pit Slope Using the Random Set Method in the Bełchatów Lignite Mine, Central Poland

The slopes of open-pit mines are often at risk of failure. To identify this hazard, stability analyses are performed. An important element of these stability analyses is the reliable selection of input parameter values for the calculations. This selection is difficult because the slopes of the open pit are disturbed by mining activities. In such conditions, rheological processes, intensified by weathering, develop in open-pit slopes. This study is aimed at setting the strength parameters for the stability analysis of open-pit slopes with a developed slide process, using the random set method. The study was performed on the example of the open pit of the Bełchatów lignite mine, central Poland. A four-stage methodology, according to the random set method, was proposed. The methodology covered the following: site investigation, sensitivity analyses, shear strength reduction (SSR) analyses using numerical calculations, and probability analyses of the factor of safety (FoS) calculation results. The setting of the input parameters took into account the peak and residual strength parameters for each lithological unit in the physical model of the open-pit slope. Samples for laboratory tests were taken from the cores of nine test boreholes. The sensitivity analysis included all peak and residual strength parameters for each lithological unit in the body. As a result of the sensitivity analysis, specific strength parameters were adopted that would have a great impact upon the results of the calculations. Selected sets of parameter values were then used for the FoS calculations. The resultant FoS values revealed the probable slide planes. The positions of the slide planes were consistent with the interpreted slide surfaces based on the control boreholes and terrain observations. Knowledge of the slide planes positions and the values of the strength parameters enabled the designing of a securing approach for this landslide, and the taking of preventive measures to reduce this risk.

Precipitation strengthening of stress-aged Al-Cu-Mg-Ag alloy single crystals

Al-Cu-Mg-Ag single crystals with five different orientations were used to study the precipitation behavior during stress aging under a stress range from 0 to 150 MPa. TEM characterization of the aged samples indicated that three kinds of precipitates Ω, S and θ′ formed, and the number density of S precipitates increased with the applied stress. The distribution of two Ω variants Ω1/Ω2 behaved preferentially oriented under higher applied stress and the anisotropic degree was various between 0.3 and 1.4, which depends on the plane orientation of single crystal. As the stress loading directions of single crystals with (6 5‾ 10), (3‾ 1 3) and (2 1 2) plane orientations are more perpendicular to the dislocation slide planes {111}, the distribution of Ω1/Ω2 in these single crystals is more homogeneous with the number ratio between 1.0 and 1.2. Considering the coupling effects of crystallographic anisotropy, stress-oriented precipitates and stress induced dislocations on precipitates, the size and distribution of Ω, S and θ’ were quantitatively counted and analyzed. The increments of precipitation strengthening were calculated and compared with the measured hardness results, indicating that the hardness of single crystal with (6 5‾ 10) orientation increase by most with 15 HV after stress aging. The trend of hardness changes with applied stress and plane orientations was well modeled in stress-aged Al-Cu-Mg-Ag single crystals.

Safety Factor on Rock Slopes with Tensile Cracks Using Numerical and Limit Equilibrium Models

Through the research it describes an analytic methodology, which allows to determine the minimum safety factor depending on the depth of tensile crack and the inclination of surface failure on the most critical condition, considering at the same time, surcharge, seismic effect and water pressure. Therefore, it studies the stability of rock slopes considering that the potential of failure surface it is constituted by two blocks with different inclinations. The superior block is limited by a tensile crack that is represented by a fracture without displacement. On the other hand, on the inferior block, geometry is formed by a potential slide plane of α inclination with the horizontal axis, in which are acting shear stresses. Fracture on superior block is characterized by a normal-tensile stresses field that act over the crack whose presence originates when the rock loses its original cohesion. Finally, comparisons are made through examples with the limit equilibrium method and finite elements method, where it determines the safety factor on dry state, water and seism, being all of them too similar. Besides, the methodology compares the track depth and the distance between the intersection point of tensile crack and the edge of the slope face, results shows that the analytic methodology is very conservative and throws the less values of this distances.

Coupled analysis of earthquake-induced permanent deformations at shallow and deep failure planes of slopes

The seismic performance of slopes is commonly evaluated by simplified sliding block analyses. In this paper, an extended sliding block model is developed to compute the earthquake-induced deformations at both shallow and deep failure planes of slopes. The coupled analytical model captures simultaneously the stick-stick, stick-slip and slip-slip behaviors of the lumped mass system of soil profile. The complex interactions between the dynamic response of the soil and the slip episodes at shallow and deep slide planes are revealed. The proposed sliding model is compared to the conventional single base-sliding analyses, and the influence of the presence of shallow failure sliding is emphasized. Then, the dynamic response and permanent displacement of slopes with different locations of the shallow sliding plane and different yield accelerations of shallow and deep sliding planes are examined. The comparisons are also performed for permanent displacements determined from the developed coupled multi-sliding procedure and from the seismic sliding model with multiple rigid blocks. Finally, an example is presented to demonstrate the procedure in the application and the differences of the results from the traditional coupled approach. The coupled model in this study provides a rigorous procedure to combine the shallow and deep failure modes for the assessment of the co-seismic landslide hazard.

Numerical simulation of deformation memory effect of rock materials in low‐stress condition using discrete element method

AbstractThe slip behavior of the pre‐existing sliding planes (eg, cracks or inter‐grain boundaries) in rocks is a natural candidate for a mechanism of the deformation memory effect. Based on this mechanism, the deformation rate analysis (DRA) method can be used to measure in situ stress in low‐stress region. However, the traditional discrete element method (DEM) is unable to model the deformation memory effect of rock when the loading stress is lower than the crack initiation stress due to the insufficient consideration for sliding planes. The simulated stress‐strain curves obtained from previous DEM are linear in initial loading stage until cracks start to grow. In the present work, the properties of planes (ie, cohesion, frictional resistance, and relocking mechanism) are introduced into DEM contact model to simulate the deformation memory effect of rock in low‐stress region, and its feasibility was confirmed by comparing it with experimental results. It is found that there exists a suitable in situ stress range for DRA method when using it in low‐stress region, among which the inflection is precise. Four factors related to the sliding planes are discussed with parametric study to study their influence on the deformation memory effect. The results show that the cohesion and dip angle are highly related to the threshold value, while the friction coefficient and fraction of slide planes have little influence on the deformation memory effect in rocks.

The role of mass transport deposits contributing to fluid escape: Neogene outcrop and seismic examples from north Taranaki, New Zealand

Many sedimentary structures are the manifestation of fluid escape in sedimentary basins. This paper examines outcrop and seismic examples in upper Miocene deep-water sandstones and siltstones of north Taranaki, New Zealand. In outcrop examples of fluid escape features comprise discordant bodies within otherwise uniformly bedded surrounding stratigraphy, features characterized by steep sided, over-hanging, vertical or near-vertical margins, infilled with an assortment of poorly sorted or chaotically arranged sandstone and siltstone. Typically, these features are several metres wide and up to 20 m high in outcrop and always occur stratigraphically below a mass transport deposit (MTD). Examples of similar features from nearby 2D and 3D seismic reflection data consist of localized vertical to sub-vertical zones of disrupted reflectivity and are as much as 300 m in height and 10’s–100’s of metres in width. The structures occur in close association with the basal slide planes of seismic-scale MTDs. The close association of fluid escape structures with MTDs suggests that these features formed by the sudden loading of the sedimentary succession by the emplacement of several metre-thick overlying MTDs. We suggest recurring phases whereby the emplacement of MTDs triggered fluid escape within underlying strata and, in turn, the fluid escape contributed to further instability with potential for mobilization and transport of subsequent MTDs in a dynamic deep-water setting.

The sedimentology and tsunamigenic potential of the Byron submarine landslide off New South Wales, Australia

Abstract Extensive evidence for submarine landslide failure is found along the east Australian continental margin. This paper assesses the sedimentological properties and models the failure event that created the Byron landslide scar, located on the SE Australian continental margin, c. 34 km off the coast of Byron Bay, New South Wales. Sedimentological analyses and dating (radiocarbon and biostratigraphic) were conducted on three gravity cores collected from within the Byron landslide scar. A paraconformity, identified in one of the three cores by a distinct colour change, was found to represent a distinct radiocarbon age gap of at least 25 ka and probably represents the detachment surface of the slide plane. The core-derived sediment properties for the Byron landslide scar were used to inform hydrodynamic modelling using the freely available numerical modelling software, Basilisk. Model results highlight the important role of sediment rheology on the tsunamigenic potential of the slide and on the resulting inundation along the east Australian coastline, therefore providing a greater understanding of the modern hazard posed by comparable future submarine landslide events for the east Australian coastline.

INTERPRETASI DATA RESISTIVITAS UNTUK MENGIDENTIFIKASI MUNCULNYA LONGSOR SUSULAN DI BLOK V WAYAME AMBON

Research of the Block V Wayame Ambon slide planes has been carried out using the geoelectric resissivity method of the Wenner-Schlumberger configuration. The purpose of the study was to estimate the structure of the subsurface rock layer and identify the distribution of slide plane based on the cross section of rock resistivity. The rock resistivity modeling results show the existence of a slip zone on both measurement trajectories. On the Line-1 it was assumed that two slide planes found at a depth of 2.0 m located at a distance of 6.0 m and 38.0 m, while on the Line-2 the slide planes are in 2.5 m depth is located at a distance of 28.0 m. The slip zone which is a landslide-prone area lies in the intermediate resistivity group (30-70 W.m) with the type of sand or clay sand which overlaps the high resistivity group (> 70 W.m) in the form of a hard claystone (bedrock). Landslide-prone zones can have the potential for a subsequent landslide to occur by allowing the potential spread of landslides to remain at their original location in the event of disturbances on the slopes and the opportunity to shift towards the top of the slope.

Struktur Resistivitas Dangkal Sebagai Upaya Mitigasi Bencana Pergerakan Tanah

Cisempur village is located at the slope of Mount Geulis, having a very variated morphology from gentle slopes to very steep ones. Due to the high demand for settlements the land use change can not be avoided. The steepness of the slope, the decrease of the number of vegetations, and the increase of load from buildings may induced land slide occurrence. This problem motivate us to perform measurement at the area, in order to uncover the information about the level of stability and the land carrying capacity, through the study of the subsurface rock layering condition. In this work, we present the shallow resistivity by means of Electrical Resistivity Tomography (ERT) method in two measurement lines. The obtained data is processed using 2D inversion method, in order to obtain the layering structure cross-section. The interpretation of the results suggest the existence of sandstone, which is normally associated with the location of aquifer and tuffaceous clay. The tuffaceous may function as the slide plane in the land slide event. The interpretation also shows that the carrying capacity decrease very extremely at the settlement site, which is indicated by the land displacement. This information has to be socialized and transferred to the inhabitant, in order to build awareness, and the land slide disaster mitigation can be carried out.

Stratigraphy and dating of a large slumping event in the Northern Aegean

Continuous seismic (Air-Gun) subbotom profiling in the N.Aegean was revealed a large submarine translational slide. The failure zone is extended from about 300m depth down to 800 m and covers an area of 85 Km2. The mean thickness of the slide reaches about 55 m and an estimated total volume of 4 Km3 of Quaternary sediments have been slided along a distance of 6 to 7 Km. Chronostratigraphic analysis of the acoustic reflectors imply that the slide plane is the muddy layer of late Pleistocene age (170-240 Ka BP). AMS dating of sediment cores provided indications that this major slide event occurred 5 to 6 Ka BP.