Landslide Volume Research Articles

Statistical analyses of landslide size and spatial distribution triggered by 1990 Rudbar-Manjil (Mw 7.3) earthquake, northern Iran: revised inventory, and controlling factors

This study is a revised inventory of landslides triggered by the Rudbar-Manjil earthquake (Mw = 7.3), 1990, obtained through the study of Komak Panah and Hafezi Moghadas (1993), interpretations of the stereoscopic aerial photos, and field data. We mapped the 223 coherent landslides with a total area of 11.3 km2 and a calculated volume of 3.8 × 108 m3 using a digital elevation model (DEM, 12.5 m) within the geographical information system (GIS) software. The correlation between landslide occurrence (size and distribution) and the controlling factors was analyzed using the bivariate model and the linear automated modeling (LINEAR) procedure in the SPSS software. Both LINEAR models of landslide volume (LV, m3) and landslide area (LA, m2) indicate the distance from the fault surface rupture is the most influencing factor on size prediction of coseismic landslides. The LA is more dependent on seismic factors, whereas the LV is on the lithology and topographic factors. The result of principal component analysis (PCA) model, using the GIS, showed that most landslides occurred in the red band (including 95% of the variance of controlling factors). Thus, the selected factors to investigate the landslide occurrence are valid and the PCA can be used to identify regions prone to coseismic landslides. The curves of landslide number density (LND, landslides/km2), landslide area percentage (LAP, landslide area/total area%), LA, and LV have a multimodal distribution (several patterns of response) by the topographic and seismic factors. It is recommended that other models be applied to better investigate the local effects of factors on the coseismic landslides.

Preliminary report of a catastrophic landslide that occurred in Gokseong County, South Jeolla Province, South Korea, on August 7, 2020

We report a catastrophic landslide occurred in Gokseong County, South Korea, on August 7, 2020. Torrential rain, with a cumulative rainfall of more than 250 mm for the preceding 3 days, contributed as a trigger or a primer to an initiation of slope failure and ensuing evolution to a debris flow. The runout length, area, and volume of the Gokseong landslide are estimated to be approximately 678 m, 4.63 × 104 m2, and 2–5 × 104 m3, respectively. This Gokseong landslide, with its long runout, has caused severe damage to the village located downstream with a total of five fatalities and five buried houses. This study not only reports the damaged area, rainfall characteristics, and triggering factors but also presents the terrain changes obtained through a field survey using unmanned aerial vehicles (UAVs) conducted 5 days after the event and the normalized difference vegetation index (NDVI) using Sentinel-2 data.

Calculation of the Coseismic Landslide Volume Using DEMs: An Example from the Yingxiu Area, Wenchuan, Sichuan, China

Volume calculation is important for quantifying the erosion driven by coseismic landslides in geomorphology. With the advent of digital elevation models (DEMs), quantifying features of landslide bodies have become possible, permitting to calculate the landslide volume in terms of elevation changes. To further test this approach, this work calculates the volume of landslides near the epicenter of the 2008 Mw 7.9 Wenchuan earthquake in the Yingxiu region, Sichuan, China, by comparing pre‐ and postearthquake DEMs. Results suggest that effective application of this method needs to consider the DEM resolution and eliminates background errors of individual landslides. The volume of coseismic landslides calculated by the proposed method may represent a minimum value compared to that from the existing empirical V-A formulas. Considering that it is difficult to quantify the coseismic landslide volume throughout in a broad region, this method can be applied to the preliminary stage of characterizing coseismic landslides quantitatively for some key localities of the affected area of major earthquakes.

A landslide granular phase transition

Landslides appear in many different forms and sizes, from devastating debris flows to overly optimistic sand castles. A familiar and well-documented feature of all landslides is the positive correlation between volume and landslide runout. Larger landslides have a greater potential to reach farther. Here we explore the low volume limit and find a surprising negative correlation between volume and landslide runout. A decrease in volume leads to an increase in runout. In a series of experiments we systematically vary the landslide volume to reveal a transition between these two regimes.

Volume Estimation of Landslide Affected Soil Moisture Using TRIGRS: A Case Study of Longxi River Small Watershed in Wenchuan Earthquake Zone, China

After the 2008 Mw 7.9 Wenchuan earthquake, geological hazards occurred frequently in the southwest mountainous watershed. Frequent landslide disasters provide abundant sediment supply for mountain torrent disasters. The estimation of the potential landslide volume is essential for the risk assessment of mountain torrent disasters. In this study, a method of calculation that combines TRIGRS and the slope-units for estimating the landslide volume of a small mountainous watershed has been established. TRIGRS analyzes the watershed landslide safety factor under rainfall conditions based on grid-cells. The slope-units extract the results and combine the empirical power law formula to calculate the potential landslide volume. In this paper, we use this method to assess the landslide volume of the Longxi river basin. The results show that the area and volume estimates of the landslides are consistent with the results observed from satellite images and field surveys. This method can be used to study the impact of sediment transport on mountain torrent disasters in the basin. With different moisture content conditions, the results show that the soil moisture content and slope angle significantly affect the distribution and volume of potential landslides in the watershed, giving rise to the uncertainty of the landslide estimation.

Mechanistic insights from emergent landslides in physical experiments

AbstractLandslides pose a major natural hazard, and heterogeneous conditions and limited data availability in the field make it difficult to connect mapped landslide inventories to the underlying mass-failure mechanics. To test and build predictive links between landslide observations and mechanics, we monitored 67.89 h of physical experiments in which an incising and laterally migrating river generated landslides by undercutting banks of moist sand. Using overhead photos (every 20 s) and 1-mm-resolution laser topographic scans (every 15–30 min), we quantified the area, width, length, depth, volume, and time of every visible landslide, as well as the scarp angles for those within 3 min prior to a topographic scan. Both the landslide area–frequency distribution and area–volume relationship are consistent with those from field data. Cohesive strength controlled the peak in landslide area–frequency distribution. These results provide experimental support for inverting landslide inventories to recover the mechanical properties of hillslopes, which can then be used to improve hazard predictions.

LANDSLIDE HAZARD IDENTIFICATION (LHI) BASED ON GEOELECTRICAL MAPPING ANALYSIS (GEM): CASE STUDY FROM LUYANG, KOTA KINABALU, SABAH, MALAYSIA

Landslides are amongst the most damaging natural hazards in Malaysia. The study of landslides has drawn nationwide attention mainly due to increasing awareness of the socio-economic impact of landslides, as well as the increasing pressure of urbanization. Landslide Hazard Identification (LHI) is part of the process used to evaluate if any particular situation, item, thing, etc. may have the potential to cause harm. The description of LHI should include the location, volume (or area), classification and velocity of the potential landslides and any resultant detached material, and the probability of their occurrence within a given period of time. In this paper, we present the results of the measurement for the subsurface resistivity within by using the pole-dipole electrode array and present the 2D view of each resistivity profile. The result presented successfully detect the dominant layer consists of interbedded sandstone and shale of the Crocker Formation with highly weathered. This both layers have high porosity and potential to contain high water content which can trigger landslide to occur. Besides that, there are several boulders zone (weathered to fresh rock) that can be found at the top of the subsurface profile at about 1.5m to 15m in depth. The bedrock layer was estimated to be found at 4m to 32.5m in depth from the original ground and one possible fault line that had been identified. This fault line believed plays a role in the occurrence of landslide in which rock materials have lower strength compared to surrounding rocks. High density of fault means lower stability. Therefore the faut line have been regarded as a critical factor in triggering landslide in the study area. The results of these study findings are expected to be used as uniform guidelines and principles are very useful and have integrity in providing coordination of standards or policies for each planning activities for new development in the future. As a result of the lack of concern for the developer of the concept of Sustainable Development Goals (SDG) or balancing and control of environmental health, the results of this study can also be used as a yardstick to party developers who intend to develop a high ground and hillside in deciding whether to continuing development planning or not.

Landslide response to vegetation by example of July 25–26, 2013, extreme rainstorm, Tianshui, Gansu Province, China

Loss Plateau of China is an area with long-term vegetation restoration while serious mass movements. Local vegetation does act as sediment reducing role while quantification of their effect on landslides is lacking. This work presents a first research work about the connection between landslides and vegetation by the example of July 25–26, 2013, extreme rainstorm. High-resolution sensing orthoimages, landside width, and simplified infinite slope theory were used to examine landslide distribution and the lateral apparent cohesion of roots. The results reveal that shallow landslides have a higher probability at the transitional slope area. The majority of them have a gradient of 20–25°, locate on south-facing slopes, and areas with sparse vegetation. Vegetation cover, represented by the Green-Red Vegetation Index (GRVI), is the controlling factor of landslide distribution and size. The estimated lateral apparent cohesion of plant roots is not positively related to GRVI, and increase when GRVI > 0.2. The relationship between landslide width and slope gradient indicates that strong root strength may result in larger landslide volume. This result of this work is a pioneering trial in correlating the lateral apparent cohesion from roots and forest crown, which is helpful for understanding the effect of vegetation on landslides.

Initiation mechanism and quantitative mass movement analysis of the 2019 Shuicheng catastrophic landslide

The 2019 Shuicheng landslide was a typical landslide in that failure occurred in the slope deposits and there was a close correlation with the antecedent rainfall. The initiation mechanism was analysed using field investigations, laboratory tests and numerical simulations and the characteristics of mass movement were quantitatively assessed. The numerical results indicated that the infiltration of rainfall decreased the shear resistance of the slope and increased the pore water pressure and soil weight, resulting in a large deformation of the slope and a gradual deterioration in its stability. After saturation, as the pore water pressure coefficient ( r u ) approached 0.3, the overall safety factor decreased to 1 and failure eventually occurred. Quantitative mass assessment showed that the unique terrain aggravated the erosion and entrainment effects and that the inclusion of loose material and water promoted the movement of the debris avalanche by changing it into a fluidized state, resulting in a much larger landslide volume with a long runout distance. As a result, the volume of the failed mass, which was calculated by an unmanned aerial vehicle and terrestrial laser scanning modelling techniques to be c. 4.7 × 10 5 m 3 in the source area, almost quadrupled to >2.0 × 10 6 m 3 .

Quantitative spatial distribution model of site-specific loess landslides on the Heifangtai terrace, China

Landslide disasters are associated with severe losses on the Loess Plateau of China. Although early warning systems and susceptibility mapping have mitigated this issue to some extent, most methods are qualitative or semi-quantitative in the site-specific range. In this paper, a quantitative spatial distribution model is presented for site-specific loess landslide hazard assessment. Coupled with multi-temporal remote sensing images and high-precision UAV cloud point data, a total of 98 loess landslides that have occurred since 2004 on the Heifangtai terrace were collected to establish a landslide volume-date and retreating distance database. Eleven loess landslides are selected to construct a numerical model for parameter back analysis, and the accuracy of the simulation results is quantitatively evaluated by the centroid distance and overlapping area. Different volumes and receding distance rates of landslides are fitted to determine the relationship between cracks and potential volume, and different volumes and parameters are combined to simulate the spatial distribution of potential loess landslides. The results of this study reveal that landslide volumes mainly range between 1 × 103 and 5 × 105 m3, and the historical occurrence probability reaches 0.551. The optimal parameters are estimated by the maximum likelihood method to obtain a uniform distribution parameter value probability model, and the results show that the error of the estimated length within a range of 0.05 from the optimal parameter does not exceed 15%. In the selected slope slide case, farmland near the toe of the slope primarily includes exposed hazards with probabilities greater than 0.7. This work provides a useful reference for local disaster reduction and a theoretical methodology for hazard assessments.

Landslide monitoring and runout hazard assessment by integrating multi-source remote sensing and numerical models: an application to the Gold Basin landslide complex, northern Washington

The landslide complex at Gold Basin, Washington, has been drawing considerable attention after a catastrophic runout of the nearby landslide at Oso, Washington, in 2014. To evaluate potential threats of the Gold Basin landslide to the campground down the slope, remote sensing and numerical modeling were integrated to monitor recent landslide activity and simulate hypothetical runout scenarios. Bare-earth LiDAR DEM (digital elevation model) differencing, InSAR (Interferometric Synthetic Aperture Radar), and offset tracking of SAR images reveal that localized collapses at the headscarps have been the primary type of landslide activity at Gold Basin from 2005 to 2019, and currently no signs indicative of movement of a large centralized block or a deep-seated main body were detected. The maximum horizontal deformation rate is 5 m/year occurring primarily from headscarp recession of the middle lobe, and the annual landsliding volume of the whole landslide complex averages 1.03 × 105 m3. From three-dimensional limit equilibrium analysis of generalized terrace structures, the maximum landslide volume is estimated as 2.0 × 106 m3. Simulations of hypothetical runout scenarios were carried out using the depth-averaged two-phase model D-claw with above-obtained landslide geometry constraints. The simulation results demonstrate that debris flows with volume less than 105 m3 only pose limited threats to the campground, while volumes over 106 m3 could cause severe damages. Consequently, the estimated maximum landslide volume of 2.0 × 106 m3 suggests a potential risk to the campground nearby. Adaption of our methodology could prove useful for evaluating other similar landslides globally for hazards prevention and mitigation.

Moraines and marls: Giant landslides of the Lago Pueyrredón valley in Patagonia, Argentina

Giant catastrophic landslides (>108 m3) dot the formerly glaciated mountain forelands of the eastern Patagonian Andes. From geomorphic mapping, sedimentological logs and radiocarbon dating, we infer the emplacement kinematics and approximate timing of giant landslides in moraines and other glacial deposits in the Lago Pueyrredón valley (LPV), Argentina. For the first time, we report in detail examples of giant low-gradient landslides with hummocky lobes derived from unconsolidated glacial deposits and weak bedrock. We find that at least 4.5 km3 of debris and weak bedrock were mobilized by slope failures in an area of ∼500 km2 since the Last Glacial Maximum (LGM; ∼25–18 ka). Nearly 90% of this landslide volume originated along the shores of, or as subaqueous failures in, a postglacial moraine-dammed meltwater lake. The larger landslides (>1 km3) detached from moraines fringing the lake, whereas other landslides displaced glacial and lake deposits either on the paleolake bed, or in a river gorge that was cut upon drainage of the glacial lake. Sequences of till, glaciofluvial and glaciolacustrine deposits overlying weak Early Miocene marlstone are mostly conducive to major landslides in the LPV. Cross-cutting relationships indicate that largest landslides in the area originated during rapid glacial lake-level drops. Distribution and internal structure of hummocks within landslide lobes suggest that these landslides were emplaced as catastrophic debris avalanches. It suggests that giant catastrophic landslides in the glacier forelands of Patagonia can result from layered weak rocks, changes in meltwater-lake levels, and possibly as a consequence of strong earthquakes linked to rapid post-glacial rebound following the retreat of the Patagonian Ice Sheet (PIS).

Characteristics of failure area and failure mechanism of a landslide in Yingjiang County, Yunnan, China

Due to excavations and continuous rainfall, two landslides occurred on February 9, 2018, and July 28, 2019, respectively, in the quarry of the Changdifang Reservoir engineering area, in Yingjiang County, Yunnan Province, China. The volume of the second landslide was approximately 2.4 × 105 m3, threatening the safety of construction workers and the hydropower station project construction severely. In order to explore the causes of these two landslides, the geological and hydrological conditions and the current excavation status of the landslide area were investigated, the relationship between rainfall and the displacement of the landslide body was compared and analyzed, and the landslide process and failure characteristics were described in detail. The failure mechanism of these two landslides were distinguished: (1) the poor rock mass properties, due to the strong weathering and tectonic joint of the rock mass; (2) the steep slope (of 63° in largest dip angle) induced by the slope excavation, as well as (3) the continuous heavy rainfall. The unfavorable geological condition was a determinant factor, and the combined effects of excavation and continuous rainfall were triggering factors that induced the landslide. The research results show that the displacement of the landslide body has significant seasonal characteristics. In the rainy season, there is a significant acceleration of displacement, and the slow displacement will remain for a long time after the rainy season. Consequently, it is very necessary to take reasonable slope treatment measures and continue to monitor the slope.

Estimating volume of deep-seated landslides and mass transport in Basihlan river basin, Taiwan

Deep-seated landslides are often caused by severe rainfall, but the displaced potential landslide mass often does not slide downslope entirely in one time. Evaluation of the mobilized volume of the deep-seated landslide and the volume of the remaining potentially unstable landslide mass on the slope is vital for hazard mitigation. In this study, an integrated method was developed for evaluation of the potential landslide volume and mass transport of deep-seated landslides caused by Typhoon Morakot in Basihlan River Basin, Taiwan. A combination of various types of remote-sensing data, including aerial photographs, satellite images, and light detection and ranging (LiDAR) data, from before and after the event were used for locating landslides, and the deep-seated landslides were identified in the Basihlan River Basin, Liuoguey District, Kaohsiung City, Taiwan. A stability analysis and a profile analysis were conducted to determine the critical sliding surface of each deep-seated landslide, and the volumes (masses) of the landslides were estimated. The total volume of all the deep-seated landslides was approximately 6,017,000 m3 in the Basihlan River Basin. A topographic analysis was performed to evaluate the mass transport of the deep-seated landslides using LiDAR-derived digital terrain models (DTMs) before and after Typhoon Morakot. The mass transport of deep-seated landslides in the Basihlan River Basin was determined to be approximately 3,527,300 m3, which suggested the volume of the remaining potentially unstable landslide mass on slope of approximately 41.4%. The available field data suggested subsequent reactivations of the deep-seated landslides after Typhoon Morakot, including debris flow generation, which damaged the infrastructure. Thus, a large landslide volume remaining in the Basihlan River Basin can cause more landslides or debris flow hazards in the future. Estimation of the potential landslide volume and mass volume remaining on slopes is essential for both short- and long-term mitigation strategies.

Application of Unmanned Aerial Vehicle (UAV)-Acquired Topography for Quantifying Typhoon-Driven Landslide Volume and Its Potential Topographic Impact on Rivers in Mountainous Catchments

Landslides are highly erosional processes that dominate sediment mobilization and reshape landscapes in orogenic belts. Therefore, quantifying and characterizing landslide volume is essential to disaster prevention and understanding landscape evolution in mountainous rivers. Progressive development of the structure-from-motion (SfM) and multi-view stereo (MVS) photogrammetric techniques and Unmanned Aerial Vehicles (UAV) provides low-cost and high-resolution digital elevation models (DEMs), compared to traditional aerial photogrammetry at the same resolution. In this study, we quantified landslide volume and change in river channel volume at meter-scale accuracy for the Laishe River catchment of southern Taiwan from 2009 to 2015, which provides reliable data for discussing sediment transport and morphological response. The observations indicate that Typhoon Morakot in August 2009, induced a landslide volume of 31.63 million (M) m3, which is equal to 87% of the six-year sediment production. Typhoon Morakot also caused the deposition of 8.2 M m3 in the Laishe River. Additionally, this study demonstrates the feasibility of using UAVs to quantify the migration of landslide material and changes in channel area and volume, and the detection of landslide dams. In conclusion, two sources of images, especially those by UAVs, were used to decipher the consequence and potential hazard, social impact, and morphological changes in a mountainous river.

Geologic Trends in Shear Strength Properties Inferred Through Three‐Dimensional Back Analysis of Landslide Inventories

AbstractLandslides occur in a variety of forms that are a function of climactic setting, tectonic setting, geomorphic and geologic setting, and the shear strength of soil and rock. While major advances in characterizing the spatial influence of these settings on landslide activity have occurred in recent years, there has been limited progress on understanding spatial trends in shear strength properties and their influence on landslide activity. Herein, we propose a regional‐scale forensic methodology to establish first‐order estimates of landslide shear strength. This approach is performed using (1) interpolation of rupture surface geometry and (2) three‐dimensional slope stability analysis. Thereafter, distributions of back‐analyzed shear strengths of landslide inventories are used to demonstrate that distinctly different trends are observed when comparing geologic units and landslide type. It is shown that there is generally an inverse correlation between landslide volume and friction angle, suggesting that larger earthflows tend to be in a residual state of shear, while smaller deep‐seated failures tend to occur in stronger, possibly cemented materials. Significant uncertainty lies in characterization of hydrological conditions; nonetheless, upper and lower bounds of groundwater conditions still reflect significant differences in inferred regional trends in shear strength properties between geologic settings. A comparison of three‐dimensional forensic back analyses to conventional, infinite slope conditions often used in susceptibility analyses suggests that conventional approaches may significantly overestimate landslide shear strengths at a regional scale.

Local tsunami run-up depending on initial localization of the landslide body at submarine slope

The numerical simulation of tsunami induced by layer-by-layer sliding of submarine slope with various initial location of landslide body is performed. For the landslide body, an elastoplastic model with layered sediments taking into account the porosity and deconsolidation of the landslide mass, resting on a relatively rigid base, is used. The characteristic parameters of the above model correspond to those of the landslide and tsunami event in the Corinth Bay on February 7, 1963 modeled by the authors (Papadopoulos et al. 2007). To numerically represent the dynamics of landslide motion numerical code FLAC is used, which in contrast to the finite element method implements an explicit finite-difference scheme for solving three-dimensional problems of continuum mechanics, and allows simulation of the nonlinear behavior of porous-saturated grounds under conditions of plastic flow above the yield stress. Because of plane slope conditions, the nonlinear system of shallow water equations is used for the numerical simulation of tsunami. The results demonstrate that at each time moment, the tsunami runup occurs at novel surface of the coastal slope that leads to complex repositioning of the shoreline point that depends on initial location of the landslide volume. Such an observation is absent in conventional (e.g. rigid block, viscoplastic etc.) models The results of the work demonstrate a rather physical picture of the process under consideration. More importantly modeling results of this work may help in identifying the generating mechanism of historical or future landslide tsunamis.

Assessment of Landslide-Induced Geomorphological Changes in Hítardalur Valley, Iceland, Using Sentinel-1 and Sentinel-2 Data

Landslide mapping and analysis are essential aspects of hazard and risk analysis. Landslides can block rivers and create landslide-dammed lakes, which pose a significant risk for downstream areas. In this research, we used an object-based image analysis approach to map geomorphological features and related changes and assess the applicability of Sentinel-1 data for the fast creation of post-event digital elevation models (DEMs) for landslide volume estimation. We investigated the Hítardalur landslide, which occurred on the 7 July 2018 in western Iceland, along with the geomorphological changes induced by this landslide, using optical and synthetic aperture radar data from Sentinel-2 and Sentinel-1. The results show that there were no considerable changes in the landslide area between 2018 and 2019. However, the landslide-dammed lake area shrunk between 2018 and 2019. Moreover, the Hítará river diverted its course as a result of the landslide. The DEMs, generated by ascending and descending flight directions and three orbits, and the subsequent volume estimation revealed that—without further post-processing—the results need to be interpreted with care since several factors influence the DEM generation from Sentinel-1 imagery.

Experimental investigation on the formation process of landslide dams and a criterion of river blockage

River blocking caused by landslide dams is a common geological disaster in mountainous regions worldwide, threatening the safety of human lives and infrastructure. However, studies on the formation process of landslide dams and the criteria of river blockage are still at an early stage. This paper built a laboratory-scale experimental apparatus for simulating the formation and evolution process of landslide dams, and then carried out a total of 29 experiments. It analyzed the common evolution stages of river blocking, including landslides, dam formation, and dam breaching in detail. Then, we investigated the influences of the landslide volume, the landslide discharge, and the water flow rate on a criterion and the time length of river blockage. The experimental results suggest that the formation condition of a landslide dam is related to the ratio of the landslide discharge to the water flow rate. Based on this understanding, we proposed a dimensionless River Blockage Criterion (RBC) to judge the formation of landslide dams. The criterion indicates that when RBC > 1.5, a landslide dam may form; otherwise, a landslide dam may not form. Additionally, the time length of river blockage was found to be related to the landslide volume and the water flow rate. Subsequently, we proposed a model for predicting the time length of river blockage and verified it by the 29 experimental results. The Baige River-blocking event, which occurred on the Jinsha River, China, in 2018, was used as a case study to further verify the RBC and the proposed model. The results show that the proposed RBC agreed well with reality, and the percentage difference between the calculated and the actual time length of river blockage was 11%. The findings of this study could contribute to the early warning and emergency response of river-blocking disasters.

Coseismic Uplift of the 1999 Mw7.6 Chi‐Chi Earthquake and Implication to Topographic Change in Frontal Mountain Belts

AbstractLarge dip‐slip earthquakes have a major contribution to mountain building while earthquake‐induced landslides lower mountains simultaneously. The amount of the coseismic uplift and landslides may dominate long‐term mountain evolution. However, how earthquakes contribute to mountain evolution through coseismic uplift and landslides is less constrained in real cases. We present the regional coseismic uplift of the 1999 Mw7.6 Chi‐Chi earthquake by using synthetic aperture radar (SAR) images and GPS. The coseismic uplift pattern is consistent with field observations showing increasing movement to the north with ~8 m of uplift toward the northern end. We estimated uplifted rock volume of 2.60 ± 1.09 km3, which is five times greater than the coseismic landslide volume. Intense erosion of the Taiwan orogen may erode elevated rocks rapidly, but the uplift and landslide distributions do not match and correlate more inversely, suggesting the frontal orogenic topography should be increased rather than annulled over earthquake cycles.