Giant Landslides Research Articles

Analyzing successive landslide dam formation by different triggering mechanisms: The case of the Tangjiawan landslide, Sichuan, China

The catastrophic Tangjiawan landslide, triggered by the 2008 Wenchuan earthquake, blocked the Duba River, impounding one of the most dangerous coseismic barrier lakes in Beichuan, China. The lake was drained by an artificial spillway within one month after the earthquake to minimize the potential dam-breach flooding risk. However, on September 5, 2016, this landslide was reactivated and dammed the river again, creating a 20-m high dam at the same location and resulting in the formation of a barrier lake with a volume of 0.6 million m3. The day after the event we carried out a field investigation of the landslide and obtained a high-resolution image and DEM using UAV. The satellite images from 2005, 2008, 2010 and 2015 were also collected to analyze the evolution of the landslide. Together with multi-temporal DEMs, the geometry and volumes of the displaced mass and the landslide dams and barrier lakes were calculated using image interpretation and 3D spatial analysis with GIS. This landslide is of great scientific interest, as it presents a good example of multiple reactivation of a pre-historical giant landslide under different triggering conditions: a reactivation of an older landslide during the Wenchuan earthquake, and a second reactivation during a rainfall event several years later. Meanwhile from the hazard assessment and prevention perspective, it is also representative as it dammed the river twice in 2008 and 2016, posing threats to both upstream and downstream areas. We infer that the successive landslides in this region could be caused by the strong tectonic activities: including earthquakes and high average uplifting rate. The results of landslide volume analysis using multi-temporal DEMs, contribute to the landslide mechanism analysis, and suggest that the landslide volume estimation is effected by the landslide type, landslide rupture surface location, and resolution of DEM. We also compare the performance of different empirical models of landslide stability and dam-breach flood parameters and discuss their application during the quick assessment of the potential hazard of the landslide dams. Generally, the successive landslide dams at the Tangjiawan site are caused by the successive landslide reactivations on an anti-dip slope controlled by strong tectonic activity and river erosion, involve with a mass of loose materials of previous landslide deposition, and possess high flood risk to the downstream area. The experience gained in this work can be used to assist the hazard assessment and the planning of the emergency measures for similar landslide dams in the future.

Geysers Valley CO2 Cycling Geological Engine (Kamchatka, Russia)

1941–2017 period of the Valley of Geysers monitoring (Kamchatka, Kronotsky Reserve) reveals a very dynamic geyser behavior under natural state conditions: significant changes of IBE (interval between eruptions) and power of eruptions, chloride and other chemical components, and preeruption bottom temperature. Nevertheless, the total deep thermal water discharge remains relatively stable; thus all of the changes are caused by redistribution of the thermal discharge due to giant landslide of June 3, 2007, mudflow of Jan. 3, 2014, and other events of geothermal caprock erosion and water injection into the geothermal reservoir. In some cases, water chemistry and isotope data point to local meteoric water influx into the geothermal reservoir and geysers conduits. TOUGHREACT V.3 modeling of Velikan geyser chemical history confirms 20% dilution of deep recharge water and CO2 components after 2014. Temperature logging in geysers Velikan (1994, 2007, 2015, 2016, and 2017) and Bolshoy (2015, 2016, and 2017) conduits shows preeruption temperatures below boiling at corresponding hydrostatic pressure, which means partial pressure of CO2 creates gas-lift upflow conditions in geyser conduits. Velikan geyser IBE history explained in terms of gradual CO2 recharge decline (1941–2013), followed by CO2 recharge significant dilution after the mudflow of Jan. 3, 2014, also reshaped geyser conduit and diminished its power.

Database of giant landslides on volcanic islands—first results from the Atlantic Ocean

Giant landslides on volcanic islands represent the largest formations which can be created in a single geological moment. Such landslides are distributed across the globe and have attracted a significant amount of research interest. Yet, no coherent attempts have been made to rationalise this information into a single online resource. This report summarises information about the structure of the recently created database of giant landslides on volcanic islands and presents some observations regarding the uncertainties inherent in the inventories. The database is being prepared over a 3-year period: the first year of the project has focused on rationalising information about giant landslides around the Atlantic Ocean while the second and third years will focus on rationalising information about such landslides from the Pacific Ocean and Indian Ocean, respectively. Using this database, it should be possible to interrogate the spatial and temporal patterns of land sliding and landslide reactivation as well as to better assess the hazard and potential risks posed by giant landslides on volcanic islands. It will be particularly interesting to see if any evidence can be found for global triggers, such as eustatic or climatic changes, instead of the more commonly expounded local triggers. Ultimately, it is hoped that the database will benefit both the geoscientific community and those agencies responsible for civil defence. This work is part of the activities of the International Consortium on Landslides, namely its International Programme on Landslides (Project n. 212). The database is available from the giant landslides project webpage: https://www.irsm.cas.cz/ext/giantlandslides .

The deformation analysis of Wenjiagou giant landslide by the distributed scatterer interferometry technique

After the deadly Ms 8.0 Wenchuan earthquake, the Wenjiagou landslide produced steep topography, a narrow gully and abundant loose sediments; these factors have contributed to the high debris flow risk in the Wenjiagou area during subsequent rainy seasons. At least five debris flows have occurred in the Wenjiagou area between September 24, 2008, and September 18, 2010, which resulted in seven casualties and an economic loss of approximately 446 million RMB. To reduce the risk of debris flows and landslides, the Wenjiagou Valley Debris Flow Control Project (WVDFCP), which cost over 2 billion RMB, was carried out and completed in 2011. The control measures of the project effectively reduced the scale and damage of the following debris flows. In this paper, the recent deformation of the giant landslide and its effect on the WVDFCP are evaluated by applying a time-series interferometric synthetic aperture radar (InSAR) technique based on distributed scatterers (DSs) to the Radardat-2 SAR data collected from June 2014 to September 2015. In addition, the experimental results show that most areas of the landslide are stable, with an average deformation rate of less than 5.0 mm/year. The results demonstrate that the control measures of the WVDFCP not only reduced the damage caused by the later debris flows but also contributed to the consolidation of the loose sediments in the Wenjiagou landslide area. The time-series InSAR technique based on the DSs of high-resolution SAR images is an important tool for deformation monitoring of earthquake-induced landslides.

Some giant submarine landslides do not produce large tsunamis

AbstractLandslides are the second most important cause of tsunamis after earthquakes, and their potential for generating large tsunamis depend on the slide process. Among the world's largest submarine landslides is the Storegga Slide that generated a large tsunami over an ocean‐wide scale, while no traces of a tsunami generated from the similar and nearby Trænadjupet Slide have been found. Previous models for such landslide tsunamis have not been able to capture the complexity of the landslide processes and are at odds with geotechnical and geomorphological data that reveal retrogressive landslide development. The tsunami generation from these massive events are here modeled with new methods that incorporate complex retrogressive slide motion. We show that the tsunamigenic strength is closely related to the retrogressive development and explain, for the first time, why similar giant landslides can produce very different tsunamis, sometimes smaller than anticipated. Because these slide mechanisms are common for submarine landslides, modeling procedures for dealing with their associated tsunamis should be revised.

Giant landslides and highstands of the Caspian Sea

Abstract The history of Quaternary sea-level changes in the Caspian Sea, the world’s largest lake, is partly enigmatic, and so is the geomorphic response of its coasts. Late Pleistocene transgressions during the Early Khvalynian (ca. 40–25 ka) inundated extensive portions of the flat, low-lying semi-desert of western Kazakhstan. Cliffs cut during these highstands form a prominent escarpment tens of kilometers to several hundred kilometers from the present coast of the Caspian Sea. Satellite images, digital terrain analysis, and field mapping reveal that >300 giant landslides intersect with this escarpment. More than 100 of these slope failures mobilized volumes >108 m3 along basal failure planes with gradients as low as ∼5°. All landslides share characteristics of lateral rock spreads involving competent limestones overlying weak and plastic claystones. From relative stratigraphy and new 14C data, we infer that catastrophic slope failure of over 41 km3 occurred mostly during Pleistocene Caspian sea-level highstands, while several landslides may have been reactivated or entirely originated during the Holocene. This largest cluster of terrestrial mass wasting in a tectonically quiescent setting offers an opportunity to understand how landslides erode low-relief landscapes subject to oscillating sea levels.

Hybrid-SAR Technique: Joint Analysis Using Phase-Based and Amplitude-Based Methods for the Xishancun Giant Landslide Monitoring

Early detection and early warning are of great importance in giant landslide monitoring because of the unexpectedness and concealed nature of large-scale landslides. In China, the western mountainous areas are prone to landslides and feature many giant complex landslides, especially following the Wenchuan Earthquake in 2008. This work concentrates on a new technique, known as the “hybrid-SAR technique”, that combines both phase-based and amplitude-based methods to detect and monitor large-scale landslides in Li County, Sichuan Province, southwestern China. This work aims to develop a robust methodological approach to promptly identify diverse landslides with different deformation magnitudes, sliding modes and slope geometries, even when the available satellite data are limited. The phase-based and amplitude-based techniques are used to obtain the landslide displacements from six TerraSAR-X Stripmap descending scenes acquired from November 2014 to March 2015. Furthermore, the application circumstances and influence factors of hybrid-SAR are evaluated according to four aspects: (1) quality of terrain visibility to the radar sensor; (2) landslide deformation magnitude and different sliding mode; (3) impact of dense vegetation cover; and (4) sliding direction sensitivity. The results achieved from hybrid-SAR are consistent with in situ measurements. This new hybrid-SAR technique for complex giant landslide research successfully identified representative movement areas, e.g., an extremely slow earthflow and a creeping region with a displacement rate of 1 cm per month and a typical rotational slide with a displacement rate of 2–3 cm per month downwards and towards the riverbank. Hybrid-SAR allows for a comprehensive and preliminary identification of areas with significant movement and provides reliable data support for the forecasting and monitoring of landslides.

Multi-event oceanic island landslides: New onshore-offshore insights from El Hierro Island, Canary Archipelago

This paper presents a combined onshore-offshore morpho-structural characterization of the El Golfo giant landslide, island of El Hierro (Canary Archipelago, Spain). Offshore data from multibeam echosounders, chirp sub-bottom profiles and multichannel seismic reflection data and onshore data coming from water wells and galleries have been analyzed. The geomorphology and the internal architecture of this giant flank collapse are defined in order to determine its multi-event nature. The subaerial headscarp shows a non-continuous arcuate profile formed by two nested semi-circular amphitheaters that extend offshore along a smooth chute, suggesting the occurrence of at least two large retrogressive events. Channels/gullies and escarpments developed along the submarine sector of the scar also indicate smaller-scale events and predominance of sediment bypass. In the lower slope, two subunits of submarine mass transport deposits (MTDs), debris avalanche, are identified on multichannel seismic reflection profiles with a total estimated volume of 318km3: ~84km3 and ~234km3, for the younger and older MTDs respectively. Data from wells and galleries show abrasion platforms with beach deposits at sea-level (0masl) formed after the landslide scar and buried by the post-collapse El Golfo lavas infill, suggesting an age at least older than 23.5–82.5Ka for the landslide.

APPLICATION OF TIME SERIES INSAR TECHNIQUE FOR DEFORMATION MONITORING OF LARGE-SCALE LANDSLIDES IN MOUNTAINOUS AREAS OF WESTERN CHINA

Western China is very susceptible to landslide hazards. As a result, landslide detection and early warning are of great importance. This work employs the SBAS (Small Baseline Subset) InSAR Technique for detection and monitoring of large-scale landslides that occurred in Li County, Sichuan Province, Western China. The time series INSAR is performed using descending scenes acquired from TerraSAR-X StripMap mode since 2014 to get the spatial distribution of surface displacements of this giant landslide. The time series results identify the distinct deformation zone on the landslide body with a rate of up to 150mm/yr. The deformation acquired by SBAS technique is validated by inclinometers from diverse boreholes of in-situ monitoring. The integration of InSAR time series displacements and ground-based monitoring data helps to provide reliable data support for the forecasting and monitoring of largescale landslide.

APPLICATION OF TIME SERIES INSAR TECHNIQUE FOR DEFORMATION MONITORING OF LARGE-SCALE LANDSLIDES IN MOUNTAINOUS AREAS OF WESTERN CHINA

Abstract. Western China is very susceptible to landslide hazards. As a result, landslide detection and early warning are of great importance. This work employs the SBAS (Small Baseline Subset) InSAR Technique for detection and monitoring of large-scale landslides that occurred in Li County, Sichuan Province, Western China. The time series INSAR is performed using descending scenes acquired from TerraSAR-X StripMap mode since 2014 to get the spatial distribution of surface displacements of this giant landslide. The time series results identify the distinct deformation zone on the landslide body with a rate of up to 150mm/yr. The deformation acquired by SBAS technique is validated by inclinometers from diverse boreholes of in-situ monitoring. The integration of InSAR time series displacements and ground-based monitoring data helps to provide reliable data support for the forecasting and monitoring of largescale landslide.

How unusual is the long-runout of the earthquake-triggered giant Luanshibao landslide, Tibetan Plateau, China?

In the Tibetan Plateau, active tectonic deformation triggers frequent earthquakes, and giant landslides associated with active faults produce serious consequences. A study of the characteristics and mechanism of a historical long-runout landslide in Luanshibao (LSB), Tibetan Plateau, China, finds a maximum sliding distance (L) of 3.83km with an elevation drop (H) of 820m. The landslide volume (V) was ~0.64–0.94×108m3, and it produced a long-runout (H/L=0.21). Recent surface offset along the sinistral strike-slip Litang-Dewu fault passes through the middle part of the landslide, which initiated on the hanging wall of the fault. Geological mapping, geophysical prospecting, trenching, and 14C dating together indicate that the LSB landslide occurred in jointed granite ca. 1980±30YBP, probably triggered by a large earthquake. Compilation of volume and runout distance data for this landslide and other previously published data for volcanic and nonvolcanic long-runout landslides yields a composite runout length-volume relation (L=12.52V0.37) that closely predicts runout of the LSB landslide, although substantial variation is noted in runout length around the central tendency.

ANALYSIS OF THE PARAMETERS OF THE ANCIENT CATASTROPHIC LANDSLIDE IN THE VALLEY OF THE RIVER PSLUH (WESTERN CAUCASUS) USING LASER SCANNING DATA

A detailed analysis of the relief structure and development of gravitational and fluvio-gravitational processes in a valley of the Mzymta river basin (Western Caucasus) was fulfilled using digital elevation models created on the basis of materials of laser scanning. We discovered and mapped a giant complex landslide with syndynamical block-and-ground flow. The genetic and age relationship of processes of various types and resulting landforms and sediments were determined. The landslide has a volume of about 32 million m3 , thickness up to 70 m; its body was displaced at a distance of 150–500 m to the WNW direction over the slip surface with inclination about 12–15°. The formation of the landslide we can presumably associate with the seismic impulse with an azimuth of 280–290°, which occurred about 830–950 A. D. Judging by the orientation of the landslide, the earthquake trigger can be a slip along the Main Caucasian fault. Simultaneously with the landslide the outburst of stone-ground mass down the valley of brook Pslushonok occurred (11–12 million m3 ). Mudflow material from the slopes of the left (southern) side of the valley constitutes a significant part of the volume of the terrace formed. The mudflow also filled the bottom of the Pslushonok valley and the part of the Psluh river valley below the mouth of the brook (the total length being 7.2–7.4 km) and created a dam across the Psluh valley, which was partly eroded after this event.

Characterization of the giant landslide at Wenjiagou by the insar technique using TSX-TDX CoSSC data

A landslide map is the most basic element for any landslide assessment, especially for giant landslides. However, due to remoteness and hazards, it is difficult to know the characteristics of these landslides after great earthquakes. In this study, the Coregistered Single look Slant range Complex(CoSSC) synthetic aperture radar (SAR) data from TerraSAR-X and its twin satellite TanDEM-X are employed to estimate a high-accuracy digital elevation model (DEM) for the giant landslide in Wenjiagou on Feb. 1, 2013, which was one of the biggest landslides triggered by the 2008 Wenchuan great earthquake. Then, compared to the DEM from SRTM, the elevation change can be estimated, and the characteristics of the Wenjiagou landslide, such as the source and deposit area, are highlighted. Based on the estimation of elevation change, the initial and deposit volumes are estimated as 5.09 × 107 m3 and 4.47 × 107 m3 respectively which are in agreement with previous field investigations by other researchers. And the results also show that using bistatic space-borne SAR data is an effective means for timely assessment of the giant landslide.

Volcanic and structural evolution of Pico do Fogo, Cape Verde

In recent months the media have drawn attention to the Cape Verde archipelago, with particular focus on the island of Fogo, the only island presently active and with an eruption that began on 23 November 2014, finally ceasing on 7 February 2015. The Monte Amarelo conical shield forms most of the 476 km2 almost circular island of Fogo. After attaining a critical elevation of about 3500 m, the Monte Amarelo shield volcano was decapitated by a giant landslide that formed a caldera‐like depression (Cha das Caldeiras), which was subsequently partially filled by basaltic nested volcanism. This younger eruptive activity culminated in the construction of the 2829 m‐high Pico do Fogo stratocone, apparently entirely made of layers of basaltic lapilli. Continued growth of the Pico do Fogo summit eruptions was interrupted in 1750, most likely after the stratocone reached a critical height. Since then, at least eight eruptions have taken place inside the landslide depression at the periphery of the Pico do Fogo cone, including the 2014–2015 eruptive event. Strong geological similarities with the Canary Islands, 1400 km to the north, have been frequently noted, probably as a consequence of a common process of origin and evolution associated with a mantle hot‐spot. These similarities are particularly evident when comparing Fogo with the Teide Volcanic Complex on Tenerife, where a lateral collapse of the Las Cañadas stratovolcano also formed a large depression (the Caldera de Las Cañadas), now partially filled with the 3718 m‐high Teide stratocone. However, important geological differences also exist and probably relate to the contrasting evolutionary stages of both islands. The Las Cañadas volcano on Tenerife formed at a late post‐erosional stage, with predominantly evolved (trachyte and phonolite) magmas, while at Fogo basaltic volcanism is still dominant.

Reactivation mechanism of ancient giant landslides in the tectonically active zone: a case study in Southwest China

The reactivation mechanism and stability of ancient landslides are the major concerns in the tectonically active zone. A detailed case study has been conducted to examine the reactivation mechanism of ancient landslides in Southwest China by investigating the reactivation process, shear strength and stability. Field investigation suggests that the reactivation of ancient giant slides, such as the Luosiwan slide, is attributed to the cumulative effect of adverse geological, structural condition and intensive artificial processes. However, long-term observation has shown that the ancient giant landslides usually remain stable in the remote area in spite of such adverse conditions. Ring shear tests also indicate high peak shear strength of the sliding zone soils. However, the shear strength decreases significantly once displacement occurs at the toe of giant landslide due to engineering construction. The construction process could be considered as the critical triggering factor for the reactivation of ancient giant landslide, which exerts sudden changes in the forces acting on the slope. Both long-term adverse geological evolution and sudden change in the strength lead to the reactivation of giant landslide. This study also suggests that liquefaction plays an important role in the failure behavior of reactivated ancient landslide. An effective drainage system has to be set up during engineering construction so as to reduce the probability of reactivation of ancient landslides.

Tien Shan Geohazards Database: Earthquakes and landslides

In this paper we present new and review already existing landslide and earthquake data for a large part of the Tien Shan, Central Asia. For the same area, only partial databases for sub-regions have been presented previously. They were compiled and new data were added to fill the gaps between the databases. Major new inputs are products of the Central Asia Seismic Risk Initiative (CASRI): a tentative digital map of active faults (even with indication of characteristic or possible maximum magnitude) and the earthquake catalogue of Central Asia until 2009 that was now updated with USGS data (to May 2014). The new compiled landslide inventory contains existing records of 1600 previously mapped mass movements and more than 1800 new landslide data. Considering presently available seismo-tectonic and landslide data, a target region of 1200km (E–W) by 600km (N–S) was defined for the production of more or less continuous geohazards information. This target region includes the entire Kyrgyz Tien Shan, the South-Western Tien Shan in Tajikistan, the Fergana Basin (Kyrgyzstan, Tajikistan and Uzbekistan) as well as the Western part in Uzbekistan, the North-Easternmost part in Kazakhstan and a small part of the Eastern Chinese Tien Shan (for the zones outside Kyrgyzstan and Tajikistan, only limited information was available and compiled).On the basis of the new landslide inventory and the updated earthquake catalogue, the link between landslide and earthquake activity is analysed. First, size–frequency relationships are studied for both types of geohazards, in terms of Gutenberg–Richter Law for the earthquakes and in terms of probability density function for the landslides. For several regions and major earthquake events, case histories are presented to outline further the close connection between earthquake and landslide hazards in the Tien Shan. From this study, we concluded first that a major hazard component is still now insufficiently known for both types of geohazards – and even totally unknown for most giant landslides: the time information. Thus, dating rockslides and any large mass movement is a crucial factor in order to better constrain related hazards. Second, we highlight the role of coupled hazards in the Tien Shan – inside the mountain range the largest disasters were caused by earthquake-triggered landslides and massive earth flows. Therefore, it is of prime importance for these mountain regions to complement single hazard assessment by coupled hazard scenarios. On the basis of these scenarios, risk evaluations may then be completed considering direct impacts on artificial dams, hydropower schemes, mining and road infrastructure as well as remote effects from possible dam breaches and mobilisation of mining and nuclear waste storages. Basic hazard and risk components are partly analysed in this paper and partly in a companion paper ‘Tien Shan geohazards database: Landslide susceptibility and impacts’.

Giant Landslides Triggered by the 1718 Tongwei Earthquake in Pan'an, Gansu Province, China

Giant Landslides Triggered by the 1718 Tongwei Earthquake in Pan'an, Gansu Province, China

Optically Stimulated Luminescence (OSL) Chronology of the Dehenglong Landslide from Longyang Gorge to Liujia Gorge along Upper Yellow River, China

AbstractGiant landslides are common along the upper Yellow River from Longyang Gorge to Liujia Gorge, and some of them even blocked and dammed the upper Yellow River. Chronology is inevitable in studying the mechanism of giant landslides. Controversy exists about the chronology of those giant landslides, and some have not yet dated. The Dehenglong landslide is the largest one among them. In this study, OSL samples were collected from lacustrine silty sediments and loess directly overlying the landslide sediments, as well as fault sediments related to the landslide. This landslide yielded an age of 89 ± 8 ka, which is identical with the fault age of 73 ± 5 ka at two sigma errors. The agreement of a topographic analysis and the absolute age of landslides imply that the formation of the Dehenglong landslide is strongly correlated with the tectonic activity.

Xijitan Landslide in Guide Basin in the Upper Reaches of the Yellow River and its Dammed Lakes

In the upper reaches of the Yellow River in the northeastern Tibetan Plateau, the uplift of the Tibetan Plateau and the erosion of the Yellow river reformed the landscape of the region and built steep slopes and terraces. A lot of giant landslides developed along the steep valley of the river. However, the influence of landslides to river terraces has been unclear because landslides development stages cannot be identified easily in field survey. In the study, the Xijitan giant landslide was analyzed by combining the remote sense analysis of geological facies and the field survey. The five development stages of the landslide and the related dammed lake were identified by analyzing the topographic features. It was concluded (1) the main Xijitan landslide was triggered by rain during the warm and wet Holocene Optimum period after ~6000 a BP. (2) The outburst of the dammed lake of the landslide reformed the dammed body to build a local terrace that is different from other regional river terraces.

Catastrophic emplacement of giant landslides aided by thermal decomposition: Heart Mountain, Wyoming

The Heart Mountain landslide of northwest Wyoming is the largest known sub-aerial landslide on Earth. During its emplacement more than 2000 km3 of Paleozoic sedimentary and Eocene volcanic rocks slid >45 km on a basal detachment surface dipping 2°, leading to 100 yr of debate regarding the emplacement mechanisms. Recently, emplacement by catastrophic sliding has been favored, but experimental evidence in support of this is lacking. Here we show in friction experiments on carbonate rocks taken from the landslide that at slip velocities of several meters per second CO2 starts to degas due to thermal decomposition induced by flash heating after only a few hundred microns of slip. This is associated with the formation of vesicular degassing rims in dolomite clasts and a crystalline calcite cement that closely resemble microstructures in the basal slip zone of the natural landslide. Our experimental results are consistent with an emplacement mechanism whereby catastrophic slip was aided by carbonate decomposition and release of CO2, allowing the huge upper plate rock mass to slide over a ‘cushion’ of pressurized material.