Landslide Source Areas Research Articles

SPH propagation back-analysis of Baishuihe landslide in south-western China

BackgroundLandslides and landslide dams are a major natural hazard causing high socioeconomic risk in inhabited mountainous areas. This is also true for vast parts of south-western China, which are highly prone to slope failures due to several factors, such as a humid climate with high precipitation in the summer months, geological predisposing factors with highly weathered sedimentary rocks and a high seismicity. In order to assess possible run-out distances and the potential of landslides to block rivers, it is crucial to understand which factors influence landslide propagation and how they can be quantified. Since it is often difficult or impossible to measure related geotechnical parameters in the field, their back analysis with a numerical modelling approach can be useful. In this study a numerical modelling analysis was implemented for the case of a complex landslide in south-western China, which transformed into a debris flow and blocked the river and a major road after heavy rainfall. For this purpose a quasi-3D smoothed particle hydrodynamics (SPH) model that can account for geotechnical slope parameters, run-out distance, velocities, and deposition heights was used. Based on field observations regarding initial landslide volume and final deposition volume, height, and length, the mechanical properties of the landslide were estimated in a back-analysis.ResultsThrough stepwise parameter optimisation the best reconstruction of the observed deposition phenomena could be achieved considering an initial landslide volume of about 0.5 million cubic meters, a triggering height of 15 m, an height of the water table equal to half the soil thickness, initial pore water pressures of about 0.6 of the liquefaction value, and non-negligible bed entrainment, which resulted in a deposition with a volume of about one million cubic meters, a length of 615 m and a mean height of 11 m. Compared to models with other parameter combinations, here the total error was minimal, while the final deposition dimensions were only slightly overestimated with regard to the observations in the field.ConclusionsThe paper outlines the potential for quantitatively interpreting the field evidence for the propagation of a complex flow-like landslide and related cascading processes, such as landslide damming. However, the analysis should take into account multiple features of the whole processes, such as the initial conditions at the landslide source area, the propagation pattern, the total volume mobilised, and the deposition characteristics. By doing so, the estimated model parameters can be implemented in future studies for the forward modelling of events at the same site, or other sites along this slope, in order to assess the potential of future river blockings through landslide deposits.

Texton-Based Ensemble Classification of Landslide Source and Transport Areas in VHR Imagery

The assessment of sediments produced, displaced, and deposited by landslides is important for hazard evaluation and mitigation. However, existing methods for landslide identification seldom address the effective separation of their internal constituents (source and transport). This letter presents a methodology to classify these constituents in very high resolution remotely sensed images. It is based on an ensemble of Texton classifiers using spectral and textural information. An experimental strategy is devised to evaluate different ensembles of features. An overall accuracy of above 90% is obtained in a cross-validation procedure in GeoEye-1 images from test sites in Madeira Island.

Colluvium supply in humid regions limits the frequency of storm-triggered landslides.

Shallow landslides, triggered by extreme rainfall, are a significant hazard in mountainous landscapes. The hazard posed by shallow landslides depends on the availability and strength of colluvial material in landslide source areas and the frequency and intensity of extreme rainfall events. Here we investigate how the time taken to accumulate colluvium affects landslide triggering rate in the Southern Appalachian Mountains, USA and how this may affect future landslide hazards. We calculated the failure potential of 283 hollows by comparing colluvium depths to the minimum (critical) soil depth required for landslide initiation in each hollow. Our data show that most hollow soil depths are close to their critical depth, with 62% of hollows having soils that are too thin to fail. Our results, supported by numerical modeling, reveal that landslide frequency in many humid landscapes may be insensitive to projected changes in the frequency of intense rainfall events.

Exploring the effect of absence selection on landslide susceptibility models: A case study in Sicily, Italy

A statistical approach was employed to model the spatial distribution of rainfall-triggered landslides in two areas in Sicily (Italy) that occurred during the winter of 2004–2005. The investigated areas are located within the Belice River basin and extend for 38.5 and 10.3km2, respectively. A landslide inventory was established for both areas using two Google Earth images taken on October 25th 2004 and on March 18th 2005, to map slope failures activated or reactivated during this interval. Geographic Information Systems (GIS) were used to prepare 5m grids of the dependent variables (absence/presence of landslide) and independent variables (lithology and 13 DEM-derivatives). Multivariate Adaptive Regression Splines (MARS) were applied to model landslide susceptibility whereas receiver operating characteristic (ROC) curves and the area under the ROC curve (AUC) were used to evaluate model performance. To evaluate the robustness of the whole procedure, we prepared 10 different samples of positive (landslide presence) and negative (landslide absence) cases for each area. Absences were selected through two different methods: (i) extraction from randomly distributed circles with a diameter corresponding to the mean width of the landslide source areas; and (ii) selection as randomly distributed individual grid cells. A comparison was also made between the predictive performances of models including and not including the lithology parameter.The models trained and tested on the same area demonstrated excellent to outstanding fit (AUC>0.8). On the other hand, predictive skill decreases when measured outside the calibration area, although most of the landslides occur where susceptibility is high and the overall model performance is acceptable (AUC>0.7). The results also showed that the accuracy of the landslide susceptibility models is higher when lithology is included in the statistical analysis. Models whose absences were selected using random circles showed a significantly better performance when learning and validation samples were extracted from the same area; whereas, conversely, no significant difference was observed when testing the models outside the training area.

Identification and characterization of rainfall events responsible for triggering of debris flows and shallow landslides

Summary The aim of this study is the development of objective and replicable methodologies for the identification, analysis and characterization of rainfall events responsible for the triggering of shallow landslides and debris flows, in order to define empirical rainfall thresholds. The study area is the province of Trento (6208 km2), located in the north-eastern Alps, and characterized by complex orography, with 70% of the area at an altitude above 1000 m. A rigorous statistical methodology has been defined for the identification of the beginning of the triggering event, based on the critical duration, i.e. the minimum dry period duration separating two stochastically independent rainy periods. The critical duration has been calculated for each rain gauge of the studied area and its variability during the months of the year has been analyzed. An analysis of the rainfall spatial variability in a neighborhood of the landslide detachment zone has been carried out. The adopted methods are: the examination of the Monte Macaion radar maps during some summer convective events, the comparison of rainfall records of rain gauges located in a 10 km buffer around the landslide, and the calculation of the Pearson’s correlation coefficient between pairs of neighboring rain gauges. The following rainfall thresholds have been then calibrated with the frequentist approach and compared: average intensity–event duration (I–D), which represents the rainfall event in its entirety, and intensity–duration associated with the event maximum return period (IRP–DRP), which considers the most critical portion of the event. In the absence of information about the landslide time of activation, the end of the triggering event has been identified using two criteria: the rainfall peak intensity and the last registration of the day. The methodology adopted for the objective identification of the beginning of the triggering event has demonstrated good applicability for rainfall induced landslides. During convective summer events the low representativeness of the rainfall information recorded at the nearest rain gauge with respect to the precipitation over the landslide source area has been evaluated as a critical issue for rainfall threshold definition.

長距離移動した融雪地すべりの発生域・移送堆積域の地形特性

長距離移動した融雪地すべりの発生域・移送堆積域の地形特性

Development and Application of Urban Landslide Vulnerability Assessment Methodology Reflecting Social and Economic Variables

An urban landslide vulnerability assessment methodology is proposed with major focus on considering urban social and economic aspects. The proposed methodology was developed based on the landslide susceptibility maps that Korean Forest Service utilizes to identify landslide source areas. Frist, debris flows are propagated to urban areas from such source areas by Flow-R (flow path assessment of gravitational hazards at a regional scale), and then urban vulnerability is assessed by two categories: physical and socioeconomic aspect. The physical vulnerability is related to buildings that can be impacted by a landslide event. This study considered two popular building structure types, reinforced-concrete frame and nonreinforced-concrete frame, to assess the physical vulnerability. The socioeconomic vulnerability is considered a function of the resistant levels of the vulnerable people, trigger factor of secondary damage, and preparedness level of the local government. An index-based model is developed to evaluate the life and indirect damage under landslide as well as the resilience ability against disasters. To illustrate the validity of the proposed methodology, physical and socioeconomic vulnerability levels are analyzed for Seoul, Korea, using the suggested approach. The general trend found in this study indicates that the higher population density areas under a weaker fiscal condition that are located at the downstream of mountainous areas are more vulnerable than the areas in opposite conditions.

Large-area analysis of soil erosion and landslides induced by rainfall: A case of unsaturated shallow deposits

Unsaturated shallow soil deposits may be affected by either superficial soil erosion or shallow landslides in adjacent or overlapping source areas and in different seasons when a different soil suction exists. The triggering analysis of both these processes is a relevant issue for the hazard analysis while the literature mostly provides specific approaches for erosion or for landslides. The paper proposes a large-area analysis for a case study of Southern Italy, consisting of unsaturated shallow deposits of loose pyroclastic (air-fall) volcanic soils that have been repeatedly affected by erosion and landslides in special seasons. For a past catastrophic event, the simulated source areas of shallow landslides are smaller than those observed in the field while the simulated eroded areas with thickness greater than 5 cm are comparable with the in-situ evidences, if the analysis takes into account high rainfall intensity and a spatially variable soil cover use. More in general, the results of the paper are consistent with the previous literature and also provide a methodological contribution about the application of distinct tools over large area. The added value is that the paper shows how the combination of distinct large-area analyses may help with understanding the dominant slope instability mechanisms. Only once this goal is fully achieved, can specific physically-based analyses be confidently performed at detailed scales and for smaller specific areas.

A study on the 10 November 2014 intense rainfall and the related landslides in the lower Lavagna valley (eastern Liguria)

On 10 November 2011 some small coastal basins of the Tigullio gulf and the middle Lavagna and Sturla valleys (eastern Liguria), were hit by an intense rainfall. Flash floods involved the city of Chiavari and shallow landslides were triggered on the slopes, causing severe damage to settlements and road network. Some buildings were destroyed and two casualties occurred at Leivi, in the lower Lavagna valley.This paper synthesizes the results of preliminary surveys carried out few days after the event in the area most affected by shallow landslides. The investigations, which are still in progress, have contributed to understand the characteristics of both triggering rainfall and landslide source areas. These achievements will be helpful in studying rainfall thresholds, shallow landslide modeling, landslide susceptibility and risk assessment for the study area.

Mechanism of the giant Seimareh Landslide, Iran, and the longevity of its landslide dams

Seimareh Landslide (SL) is globally recognized as one of the largest rock mass movements in the world. It is located along the border of Ilam and Lorestan provinces in southwest Iran, in the heart of the Zagros Mountain Range. There are controversial findings about the mechanism of the landslide formation. This field work study reviewed the possible mechanisms of failure and analyzed post-failure geomorphic features. Drainage pattern disturbance in the depositional region and consequent dammed lake formation are among the most significant characteristics of these features. Seimareh, Jaidar and Balmak are three large landslide-dammed lakes. The present study analyzed the processes responsible for the formation and erosion of the Jaidar and Seimareh Landslide dams using the available annual sedimentation and field measurements of the sediment deposited in these lakes. The results showed that the SL dam has been formed about 935 years after the landslide event. Detailed field investigations indicated a specific hydro-morphological condition in the landslide area. The results implied that the main causes of the failure were probably the particular hydro-morphological characteristic of the landslide source area together with the enormous eroding energy resulted from merging of two high-flow rivers which eroded the base of the southern flank of Kabir-kuh Mountain. However, the unusual size of the landslide suggests that an external factor, e.g., a huge earthquake, might have triggered the failure.

Estimation of soil properties of shallow landslide source areas by dynamic penetration tests: first outcomes from Northern Tuscany (Italy)

In Northern Tuscany (Italy) rapid, shallow landslides often cause casualties and severe damage. Aimed at contributing to the characterisation of the source areas of rapid, shallow landslides, this paper deals with the geotechnical parameterisation of the mainly involved soil by means of dynamic penetration tests. The source areas are usually located in difficult access sites, where boring and undisturbed sampling are very hard and onerous. Therefore, the results of 177 dynamic penetration tests were analysed, including dynamic probing (DP) tests and standard penetration tests (SPT). The results of these tests were related to relative density Dr and friction angle Φ′ of the soil by means of empirical equations. The distribution and variability of these parameters were analysed and related to soil type, test type and probing depth. The Dr and Φ′ values coming from the DP and SPT tests were found to be comparable. The Φ′ values coming from DP tests and direct shear tests showed an acceptable correlation, confirming the utility of the DP tests. The DP test can thus be an effective tool in the estimation of the properties of potentially unstable soil slope covers.

Analysis of landslide dams induced by the 2008 Wenchuan earthquake

Landslide dams caused by earthquakes are extremely hazardous disruptions of the flow of water and sediment in mountain rivers, capable of delivering large outburst floods that may devastate downstream areas. We analyzed a unique inventory of 828 landslide dams triggered by the Mw 7.9 2008 Wenchuan tectonic earthquake, China, constituting ∼1.4% of the >60,000 coseismic slope failures mapped and attributed to this event. While 501 landslides blocked the rivers completely, the remainder caused only partial damming or channel diversion. The spatial distribution of landslide dams follows the same trend of that of the total landslide distribution, with landslide dams being most abundant in the steep watersheds of the hanging wall of the Yingxiu-Beichuan Thrust Fault, and in the northeastern part of the strike-slip fault near Qingchuan. Besides the co-seismic landslide density, the river width also played a key role in determining the landslide dam formation. Narrow rivers are more prone to be dammed than the wide rivers. The correlation between river width and landslide dam volume follows a linear relation, which can be used to roughly estimate the dam formation possibility. However, the applicability of this correlation needs to be validated in other regions. The decay (failure) rate of dams, defined here as the percentage of the number and area of landslide dams that have failed over time, shows that ∼25% of dams accounting for ∼30% of total landslide dam area failed one week after the earthquake. These percentages increased to ∼60% within 1month, and to >90% within 1year. The geomorphometric parameters were analyzed, revealing power-law relations between landslide area and dam width, landslide source area and dam area, as well as lake area and lake volume. The inventory presented in this study will enrich the worldwide earthquake-induced landslide dam database and will also contribute to a better understanding of the post-earthquake dam decay.

Estimating the timing and location of shallow rainfall‐induced landslides using a model for transient, unsaturated infiltration

Shallow rainfall‐induced landslides commonly occur under conditions of transient infiltration into initially unsaturated soils. In an effort to predict the timing and location of such landslides, we developed a model of the infiltration process using a two‐layer system that consists of an unsaturated zone above a saturated zone and implemented this model in a geographic information system (GIS) framework. The model links analytical solutions for transient, unsaturated, vertical infiltration above the water table to pressure‐diffusion solutions for pressure changes below the water table. The solutions are coupled through a transient water table that rises as water accumulates at the base of the unsaturated zone. This scheme, though limited to simplified soil‐water characteristics and moist initial conditions, greatly improves computational efficiency over numerical models in spatially distributed modeling applications. Pore pressures computed by these coupled models are subsequently used in one‐dimensional slope‐stability computations to estimate the timing and locations of slope failures. Applied over a digital landscape near Seattle, Washington, for an hourly rainfall history known to trigger shallow landslides, the model computes a factor of safety for each grid cell at any time during a rainstorm. The unsaturated layer attenuates and delays the rainfall‐induced pore‐pressure response of the model at depth, consistent with observations at an instrumented hillside near Edmonds, Washington. This attenuation results in realistic estimates of timing for the onset of slope instability (7 h earlier than observed landslides, on average). By considering the spatial distribution of physical properties, the model predicts the primary source areas of landslides.

3-D slope stability analysis: A probability approach applied to the nice slope (SE France)

Recent geophysical and geotechnical data acquired on the Nice shelf to the east of the 1979 landslide source area, suggest slow deformations processes which could lead to future catastrophic slope failure. According to these preliminary interpretations, it is of major interest to perform a slope stability evaluation to define the hazard and quantify the danger related to a probable instability on this slope. A probabilistic approach is proposed here using a modified version of the SAMU_3D model, a 3-D slope stability software recently developed by Sultan and others to account for complex geometry. The 3-D analysis is based on the upper bound theorem of plasticity developed by Chen and others. One of the main features of the original model is to allow complex critical failure surfaces, suitable for complex bathymetry (i.e. canyons). A probabilistic approach was added to the former deterministic model to consider the effect of sediment parameter variability and uncertainty (undrained shear strength and unit weight) on the likelihood of failure. Such an approach allows an estimation of the reliability of the results. Monte Carlo simulation was used to represent the variability of the factor of safety given a specific number of trials. Identification of the critical failure surface previously based on a deterministic analysis is thus performed in terms of probability of failure (or probability of a factor of safety lower than a reference value). According to the undrained shear strength distribution profiles with depth, obtained using different models (down to 30 and 60 m depth) at several sites and to the parameter uncertainty, high probability of failure (around 50%) is found for the Nice slope indicating that the sediment in this area is highly metastable.

Susceptibility analysis of shallow landslides source areas using physically based models

Rainfall-induced shallow landslides of the flow-type involve different soils, and they often cause huge social and economical disasters, posing threat to life and livelihood all over the world. Due to the frequent large extension of the rainfall events, these landslides can be triggered over large areas (up to tens of square kilometres), and their source areas can be analysed with the aid of distributed, physically based models. Despite the high potential, such models show some limitations related to the adopted simplifying assumptions, the quantity and quality of required data, as well as the use of a quantitative interpretation of the results. A relevant example is provided in this paper referring to catastrophic phenomena involving volcaniclastic soils that frequently occur in southern Italy. Particularly, three physically based models (SHALSTAB, TRIGRS and TRIGRS-unsaturated) are used for the analysis of the source areas of huge rainfall-induced shallow landslides occurred in May 1998 inside an area of about 60 km2. The application is based on an extensive data set of topographical, geomorphological and hydrogeological features of the affected area, as well as on both stratigraphical settings and mechanical properties of the involved soils. The results obtained from the three models are compared by introducing two indexes aimed at quantifying the “success” and the “error” provided by each model in simulating observed source areas. Advantages and limitations of the adopted models are then discussed for their use in forecasting the rainfall-induced source areas of shallow landslides over large areas.

Groundwater processes in a complex landslide, northern Apennines, Italy

Abstract. The hydrogeological characteristics of roto-translational slides in flysch are complex, due to the inherent anisotropy and heterogeneity of rock masses and related deposits. The paper deals with the hydrogeological characterization of a reactivated roto-translational slide affecting Cretaceous flysch rocks, located in the northern Apennines of Italy. Continuous monitoring of groundwater levels, in-situ permeability and pumping tests, hydrochemical and physical analyses and Uranine tracers were the adopted prospecting methods. In this research hydrological monitoring and investigation are summarized in order to define a hydrogeological conceptual model of the landslide source area. Results showed that two overlaying hydrogeological units exist at the slope scale: the first is unconfined, but highly compartmentalized, and hosted in the fractured and dismembered rock slide body. The second is confined and lays in the undisturbed flysch below the sliding surface. The groundwater level in the confined hydrogeological unit is twenty meters higher than the groundwater level in the uppermost one. Moreover, the groundwater chemistry characterization revealed a rising of deep fluids in the landslide area.

Landslide rupture and the probability distribution of mobilized debris volumes

Landslide‐driven erosion is controlled by the scale and frequency of slope failures and by the consequent fluxes of debris off the hillslopes. In this paper, we tackle the magnitude‐frequency part of the process and develop a theory of initial slope failure and debris mobilization that reproduces the heavy‐tailed distributions (probability density function or PDFs) observed for landslide source areas and volumes. Landslide rupture propagation is treated as a quasi‐static, noninertial process of simplified elastoplastic deformation with strain weakening; debris runout is not considered. The model tracks the stochastically evolving imbalance of frictional, cohesive, and body forces across a failing slope and uses safety factor concepts to convert the evolving imbalance into a series of incremental rupture growth or arrest probabilities. A single rupture is simulated with a sequence of weighted “coin tosses” with weights set by the growth probabilities. Slope failure treated in this stochastic way is a survival process that generates asymptotically power‐law‐tail PDFs of area and volume for rock and debris slides; predicted scaling exponents are consistent with analyses of landslide inventories. The primary control on the shape of the model PDFs is the relative importance of cohesion over friction in setting slope stability; the scaling of smaller, shallower failures, and the size of the most common landslide volumes, are the result of the low cohesion of soil and regolith, whereas the negative power‐law‐tail scaling for larger failures is tied to the greater cohesion of bedrock.

Combined landslide inventory and susceptibility assessment based on different mapping units: an example from the Flemish Ardennes, Belgium

Abstract. For a 277 km2 study area in the Flemish Ardennes, Belgium, a landslide inventory and two landslide susceptibility zonations were combined to obtain an optimal landslide susceptibility assessment, in five classes. For the experiment, a regional landslide inventory, a 10 m × 10 m digital representation of topography, and lithological and soil hydrological information obtained from 1:50 000 scale maps, were exploited. In the study area, the regional inventory shows 192 landslides of the slide type, including 158 slope failures occurred before 1992 (model calibration set), and 34 failures occurred after 1992 (model validation set). The study area was partitioned in 2.78×106 grid cells and in 1927 topographic units. The latter are hydro-morphological units obtained by subdividing slope units based on terrain gradient. Independent models were prepared for the two terrain subdivisions using discriminant analysis. For grid cells, a single pixel was identified as representative of the landslide depletion area, and geo-environmental information for the pixel was obtained from the thematic maps. The landslide and geo-environmental information was used to model the propensity of the terrain to host landslide source areas. For topographic units, morphologic and hydrologic information and the proportion of lithologic and soil hydrological types in each unit, were used to evaluate landslide susceptibility, including the depletion and depositional areas. Uncertainty associated with the two susceptibility models was evaluated, and the model performance was tested using the independent landslide validation set. An heuristic procedure was adopted to combine the landslide inventory and the susceptibility zonations. The procedure makes optimal use of the available landslide and susceptibility information, minimizing the limitations inherent in the inventory and the susceptibility maps. For the established susceptibility classes, regulations to link terrain domains to appropriate land rules are proposed.

Incorporating the effects of topographic amplification and sliding areas in the modeling of earthquake-induced landslide hazards, using the cumulative displacement method

A procedure that considers topographic effects and runout behavior is proposed for analyzing seismic landslide hazards. The theoretical topographic amplification factors and corresponding amplified ground motion are calculated. By using the amplified motion, a cumulative displacement map is generated through the Newmark's displacement method. The high displacement areas are defined as the source areas of landslides. A runout simulation that identifies sliding routes and the final deposition areas of the sliding material from these source areas is performed. Finally, the complete set of landslide zones, including source, and sliding and deposition areas, is predicted. The landslide hazard maps of the Mt. Baishiya region, Nantou, Taiwan are evaluated, and the maps of actual landslides triggered by the September 21st, 1999, Chi-Chi earthquake are compared with the prediction. The results show that the proposed procedure, which combines topographic effects and runout simulation, can generate more accurate predictions for seismic landslide hazard analysis. However, this slight improvement over the procedure that only considers topographic effects is within the uncertainty levels of the input parameters. This slight improvement is obtained by a relatively complex and time-consuming procedure, and further research is required towards evaluating the viability of the proposed model when topographic effects cannot be neglected.

A geotechnical investigation of the retrogressive Yaka Landslide and the debris flow threatening the town of Yaka (Isparta, SW Turkey)

In this study the factors affecting the retrogressive Yaka Landslide, its mechanism and the hazard of debris flow on the town of Yaka are investigated. In the landslide area, the first landslide was small and occurred in March 2006 on the lower part of the Alaardic Slope near the Gelendost District town of Yaka (Isparta, SW Turkey). The second, the Yaka Landslide, was large and occurred on 19 February 2007 in the soil-like marl on the central part of Alaardic Slope. The geometry of the failure surface was circular and the depth of the failure surface was about 3 m. Following the landslide, a 85,800 m3 of displaced material transformed to a debris flow. Then, the debris flow moved down the Eglence Valley, traveling a total distance of about 750 m. The town of Yaka is located 1,600 m downstream of Eglence Creek and hence poses a considerable risk of debris flow, should the creek be temporarily dammed as a result of further mass movement. Material from the debris accumulation has been deposited on the base of Eglence Valley and has formed a debris-dam lake behind a debris dam. Trees, agricultural areas, and weirs in the Eglence Creek have seen serious damage resulting from the debris flow. The slope angle, slope aspect and elevation of the area in this study were generated using a GIS-based digital elevation model (DEM). The stability of the Alaardic Slope was assessed using limit equilibrium analysis with undrained peak and residual shear strength parameters. In the stability analyses, laboratory test results performed on the soil-like marls were used. It was determined that the Alaardic Slope is found to be stable under dry conditions and unstable under completely saturated conditions. The Alaardic Slope and its vicinity is a paleolandslide area, and there the factor of safety for sliding was found to be about 1.0 under saturated conditions. The Alaardic Slope and the deposited earthen materials in Eglence Creek could easily be triggered into movement by any factors or combination of factors, such as prolonged or heavy rainfall, snowmelt or an earthquake. It was established that the depth of the debris flow initiated on the Yaka Landslide reached up to 8 m in Eglence Creek at the point it is 20 m wide. If this deposited material in Eglence Creek is set into motion, the canal that passes through Yaka, with its respective width and depth of 7 and 1.45 m, could not possibly discharge the flow. The destruction or spillover of this canal in Yaka could bring catastrophic loss to residents which are located within 3–5 m of the bank of the canal. Furthermore, if material present in the landslide source area slides and this displaced material puts pressure on the unstable deposited material in Eglence Creek, even more catastrophic loss would occur to the town of Yaka. In this study, it was determined that debris flows are still a major hazard to Yaka and its population of 3,000. The results provided in this study could help citizens, planners, and engineers to reduce losses caused by existing and future landslides and debris flow in rainfall and snowmelt conditions by means of prevention and mitigation.