Prehistoric Landslides Research Articles

A long-term context for the 1663 Charlevoix CE earthquake interpreted from the postglacial landslide record in the Gouffre Valley, Quebec, Canada

This paper examines the distribution, stratigraphy and chronology of landslide deposits within the Gouffre Valley to provide a long-term context for the 1663 CE M 7.0–7.5 Charlevoix earthquake, Charlevoix-Kamouraska Seismic Zone (CKSZ), southern Quebec, Canada. Our mapping utilized a 1 × 1 m digital terrain model, and we interpreted deposit age and stratigraphy from 30 new AMS radiocarbon ages, supplemented by 51 regular radiocarbon ages and 23 dendrochronology ages compiled from previous studies. These data provide a robust chronological connection between the 1663 CE earthquake and large-scale landslide deposits that cover about 24 km2, extend about 20 km along the valley bottom, and originated from separate source areas. Eight, relatively small-scale (less than 0.48 km2), prehistoric landslide features are also present in the Gouffre Valley, including three dated landslides, aged between about 7950–7300, 6595–6087, and 1310–1200 cal BCE, a poorly-constrained deposit aged between 4782–4452 BCE and 1663 CE, and four landslides of unknown age. There is no evidence to support an earthquake trigger for any of these prehistoric landslides. Instead, the widespread deposits associated with the 1663 CE earthquake represent the only multi-event, landslide signature in the Gouffre Valley. This, in combination with a long gap between early postglacial and late Holocene mass movement activity in several nearby lakes, is consistent with the 1663 CE earthquake being the largest to occur in the CKSZ over the past about 10 ka.

Reconstruction of a Holocene landslide-dammed lake in the Yalong basin, eastern Tibetan Plateau

The failures of natural dams formed by landslides and glaciers in mountain areas have triggered the most destructive flood events on Earth. Outburst floods are effective agents in modifying landscapes, such as carving bedrock gorges and transporting surface masses. Reconstructing the ages and magnitudes of prehistoric landslide damming events allows us to capture the full range of frequencies and magnitudes of similar events and deepen our understanding of the interaction between large landslides and trunk rivers in tectonically active high-relief mountains. Previous studies have revealed many paleo-landslide-dammed lakes in the Yarlung Tsangpo River and its tributaries, the Jinsha River and the Min River. However, most studies associated with paleo-event reconstruction lack an estimation of the extent and volume of paleo-landslide-dammed lakes. The paleo-level of a landslide-dammed lake can be recorded in the variation in the sedimentary sequence and the geometry of the breach channel of a landslide dam. This information has not been fully exploited. In this study, we identified sedimentary evidence formed by an ancient landslide-dammed lake in the Liqiu River, a left-bank tributary of the Yalong River. The 12 exposures that we investigated mainly consist of typical clay or silt varves deposited in deep water and the Bouma sequence deposited by subaqueous turbidity flows, as well as climbing ripples that formed in a near-shore environment. Based on sedimentary analysis, we inferred that the minimal lake volume of this ancient lake was approximately 2.4 × 108 m3, corresponding to a lake level at 3,187 m a.s.l. The maximal lake extent derived from relict dam morphology reveals a lake volume of 3.2 × 108 m3 at the level of 3,200 m a.s.l. An initial drainage that occurred as the lake water overtopped the landslide dam was suggested to explain the small discrepancy in the lake level. The relict lake has remained stable over a long period of time and has accommodated continuous clay varve deposits. Furthermore, the optically stimulated luminescence dating results illustrate that the dammed lake initiated before 7.9 ka BP and persisted until at least 3.9 ka BP. The long-term cumulative coupled effect of tectonic movement and the rapid river incision rate provided favorable conditions for the failure of the Yuting landslide.

Geological Exploration, Landslide Characterization and Susceptibility Mapping at the Boundary between Two Crystalline Bodies in Jajarkot, Nepal

The geology of the Himalayas is intricated and intriguing. It features numerous tectonic bodies and structures too complex to interpret. Along with such mysteries it has too many common geohazards, such as landslides. In this study, a detailed geological investigation is carried out to overcome the discrepancies in structural interpretation, the nature of two crystalline bodies, and non-uniformity in geological mapping in the central Himalayan arc, in the Jajarkot district of Nepal. Along with the geological exploration and landslide characterization of the area, consequent landslide susceptibility mapping is performed considering 13 causative factors related to geology, topography, land use, hydrology, and the anthropogenic factor, using two bivariate statistical models. This study concludes that the two metamorphic crystalline bodies in the study area are most probably the klippen, due to the absence or erosion of the root zone. The field study revealed that haphazard road excavation without the consideration of geological and geotechnical features has caused shallow landslides. The results obtained from the susceptibility maps, with a varying range of susceptibility zones, are in good agreement with the spatial distribution of pre-historic landslides. The results of the susceptibility modeling are validated by calculating landslide density and plotting area under curves (AUC). The AUC value for the WOE, and the FR method, revealed an overall success rate of 79.42% and 77.62%, respectively.

Radiocarbon Dating of the Nyixoi Chongco Rock Avalanche, Southern Tibet: Search for Signals of Seismic Shaking and Hydroclimatic Events

Landslides are important agents of the surface processes involved in the growth of mountainous topography. Dating prehistoric landslides is a prerequisite for establishing the relationships between prehistoric slope instability, and past climatic regimes and paleoseismic records. The Nyixoi Chongco rock avalanche (NCRA) is located in the Angang graben within the N–S trending rift zone in southern Tibet. It represents a giant prehistoric mass wasting event that was characterized by exceptional mobility and a large volume. However, the exact emplacement time and origin of the NCRA are still controversial. In this study, we conducted 14C dating of peat layers and snail shells to constrain the emplacement age of the NCRA. The 14C ages of the organic material and plant remnants in the basal peat layer are 1272–1389 and 1299–1404 cal AD, respectively. The 14C ages of aquatic snail shells and the bog overlying the rock avalanche are 425–565 and 1022–159 cal AD, respectively. These results indicate that the NCRA consisted of at least two separate and distinct events, instead of the single event suggested by previous studies. Based on field investigations and temporal correlations, we infer that there may be no paleoseismic records in the Angang graben that would corroborate a coseismic trigger for the NCRA. Therefore, we suggest that the 14C ages of the sediments below and above the landslide rocks should be interpreted carefully. The 14C ages alone do not provide sufficient evidence to infer the true trigger of the NCRA event.

Role of Prehistoric Landslides in Recent Landscape Evolution in Batote-Baglihar Area, Nw Himalaya: Identification and Implications on Recent Mass Movement Activities

Role of Prehistoric Landslides in Recent Landscape Evolution in Batote-Baglihar Area, Nw Himalaya: Identification and Implications on Recent Mass Movement Activities

Forensic Investigation of Backyard Landslide with a Sewer in Bethel Park, Pennsylvania

AbstractIn a southern suburb of Pittsburgh, Pennsylvania (PA), a portion of a housing development was constructed in the 1950s on an unrecognized, marginally stable prehistoric landslide mass. Grad...

Geohazards and human settlements: Lessons learned from multiple relocation events in Badong, China – Engineering geologist's perspective

Abstract Mountainous regions are inherently susceptible to geohazards, such as landslides and debris flows, with the threat of natural disasters compounded by human activities (mainly settlements). Lessons learned from past events that involved the interactions between human activities and geohazards are helpful for future site selections of human settlements in mountainous regions. To this end, the events associated with county seat relocations in Badong, a typical county in the Three Gorges Reservoir region, China, are studied from an engineering geologist's perspective. Over its history, the county seat was relocated multiple times, with the first relocation traced back to the Song dynasty (960–1279 CE) and the last two relocations linked to the Three Gorges Dam project. By studying geohazards and their interactions with human activities in these county-seat relocations, and through the reconstruction of these events, we secure insights into decision-making for these events. As part of the reconstruction of these relocation events, we analyze a giant pre-historic landslide, whose discovery ultimately prompted the third relocation. Using the case history of this landslide, we also discuss and emphasize the importance of proactive monitoring of geohazards for disaster resilience enhancement, recognizing that our knowledge of nature is vastly incomplete.

Using pre-failure and post-failure remote sensing data to constrain the three-dimensional numerical model of a large rock slope failure

Factors governing rock slope stability include lithology, geological structures, hydrogeological conditions, and landform evolution. When certain conditions are met, rock slopes may become unstable, inducing deformation and failure. In the present study, an integrated remote sensing-numerical modeling approach investigates the deformation mechanisms leading to the 1965 Hope Slide, BC, Canada and the effect of slope kinematics on the long-term evolution of the slope. Pre- and post-failure datasets were used to perform a large-scale geomorphic and structural characterization, including kinematic and block-theory analyses. Extensive data collection was also undertaken using state-of-the-art remote sensing techniques, including digital photogrammetry (Structure-from-Motion), laser scanning (aerial and terrestrial), and infrared thermography. New evidence is provided that one or more prehistoric failures caused the removal of a key-block, and the initiation of long-term slope deformation and cumulative slope damage ultimately resulting in the catastrophic 1965 event. Detailed characterization of the rock slope has allowed the first three-dimensional, distinct element numerical model of the Hope Slide to be conducted. The results of the numerical simulations involving gradual reduction of the rupture surface shear strength indicate that 1965 slope failure may represent the outcome of a long-term, progressive failure mechanism that initiated after a prehistoric landslide. This combined field mapping–remote sensing–numerical modeling study clearly highlights the role of 3D slope kinematics on the geomorphic evolution of the slope, along with the associated failure mechanisms.

Developing conceptual models for the recognition of coseismic landslides hazard for shallow crustal and megathrust earthquakes in different mountain environments – an example from the Chilean Andes

Landslides represent the most frequent geological hazard in mountainous environments. Most notably, landslides are a major source of fatalities and damage related to strong earthquakes. The main aim of this research is to show through three-dimensional engineer-friendly computer drawings, different mountain environments where coseismic landslides could be generated during shallow crustal and megathrust earthquakes in the Andes of central Chile. We have determined topographic, geomorphological, geological and seismic controlling factors in the occurrence of earthquake-triggered landslides from: (1) a comparison of local earthquake-induced landslide inventories in Chile (the M w 6.2, shallow crustal Aysén earthquake in 2007 (45.3° S) and the M w 8.8, megathrust Maule earthquake in 2010 (32.5°S–38.5°S)) with others from abroad; and (2) analysis of large, prehistoric landslide inventories proposed as likely induced by seismic activity. With these results, we have built four representative geomodels of coseismic landslide geomorphological environments in the Andes of central Chile. Each one represents the possible landslide types that could be generated by a shallow crustal earthquake v. those likely to be generated by a megathrust earthquake. Additionally, the associated hazards and suggested mitigation measures are expressed in each scenario. These geomodels are a powerful tool for earthquake-induced landslide hazard assessment. Thematic collection: This article is part of the Ground models in engineering geology and hydrogeology collection available at: https://www.lyellcollection.org/cc/Ground-models-in-engineering-geology-and-hydrogeology

Four-dimensional surface motions of the Slumgullion landslide and quantification of hydrometeorological forcing

Landslides modify the natural landscape and cause fatalities and property damage worldwide. Quantifying landslide dynamics is challenging due to the stochastic nature of the environment. With its large area of ~1 km2 and perennial motions at ~10–20 mm per day, the Slumgullion landslide in Colorado, USA, represents an ideal natural laboratory to better understand landslide behavior. Here, we use hybrid remote sensing data and methods to recover the four-dimensional surface motions during 2011–2018. We refine the boundaries of an area of ~0.35 km2 below the crest of the prehistoric landslide. We construct a mechanical framework to quantify the rheology, subsurface channel geometry, mass flow rate, and spatiotemporally dependent pore-water pressure feedback through a joint analysis of displacement and hydrometeorological measurements from ground, air and space. Our study demonstrates the importance of remotely characterizing often inaccessible, dangerous slopes to better understand landslides and other quasi-static mass fluxes in natural and industrial environments, which will ultimately help reduce associated hazards.

Acceleration of the Pissouri landslide, Cyprus

The residential development of Limnes in Pissouri, Cyprus was constructed on a slope formed by a pre-historic landslide. Reactivated ground movements within this landslide, first noticed by residents in 2012, continue to cause significant damage to property. The rates of movement, already observed to be accelerating between 2014 and 2017, increased by up to a factor of three during and following the very wet winter of 2018–19. The outcome has been a marked increase in architectural and structural damage to some properties, as well as building rotation in the both vertical and horizontal planes. An interpretation of the most recent InSAR results suggests that the area behind the back scarp may also now be undergoing displacement and this, to an extent, is borne out by observed cracking to some buildings and paved surfaces in the vicinity. Uncertainties remain over the depth(s) of sliding and the groundwater regime within the landslide mass that can only be resolved through further ground investigation and subsurface monitoring.

Paradise from Cataclysm: Zion Canyon’s Sentinel Landslide

Zion Canyon hosts millions of visitors each year, yet few are aware of the massive prehistoric landslide that played an important role in shaping the iconic landscape. South of the Sand Bench trailhead and bridge, a large hill encroaches on the canyon bottom around which the North Fork Virgin River flows. North of the bridge, Zion Canyon’s fl at bottom stretches into the distance. The hill is part of an enormous rock avalanche deposit known as the Sentinel slide that is nearly 2 miles (3.2 km) long and more than 650 feet (200 m) thick. After failure, the Sentinel rock avalanche dammed the North Fork Virgin River creating a lake (known as Sentinel Lake) which persisted for approximately 700 years (Grater, 1945; Hamilton, 1976; Castleton and others, 2016). Over the course of the lake’s lifetime, sediment settled at the bottom of the lake to create thick deposits of mud, clay, and sand. Sediment eventually fi lled in the canyon bottom behind the landslide dam, and the lake ceased to exist. Th ese sediment layers are still visible today and are responsible for the remarkably fl at fl oor of upper Zion Canyon (Grater, 1945; Hamilton, 2014; Castleton and others, 2016).

Reconstruction of a large runout landslide in the Krušné hory Mts. (Czech Republic)

The aims of this study were to summarize current knowledge of a large runout prehistoric landslide, critically review all of the existing data and, in particular, gather new data in order to estimate the age of the accumulation and reveal the movement mechanism. The reconstruction of a large rockslide-rock avalanche in the NW part of the Czech Republic was supported by the analysis and interpretation of 216 boreholes and by GIS analysis of the original 1950s pre-mining surface using digitized old military topographic maps. For the age estimation, we used the Schmidt hammer test. The total volume of the quaternary deposit was calculated to be between 25.4 and 27.4 mil m3, occupying an area of 778,000 m2 and consisting of six to eight generations of colluvial sediments. Three main landslide events were identified based on extensive Schmidt hammer sampling, and the approximate age was established using a regression equation assembled by Engel (2007). All three of the documented events occurred around the time of significant climate change. The oldest event occurred due to the Oldest Dryas warming, the largest event probably occurred at the end of the Younger Dryas (11,700 yBP), and the youngest of the documented events was purely of a Holocene age, with the highest landslide frequency being during the Atlantic temperature fluctuations (approximately 8200 yBP). The slope deformation occurred on a fault slope with a relative height of over 400 m and in tectonically weakened rocks. Sediments in the Most Basin were weakened from meltwater during rapid warming periods, which allowed mobilization of rockslide deposits and runout of up to 1000 m from the mountain foothills.

CORRELATIONS BETWEEN FLUVIAL KNICKPOINTS AND RECURRENT LANDSLIDE DAMS ALONG UPPER INDUS RIVER

TThis article summarizes an investigation into the likely role of landsliding in the formation of knickpoints along the Indus River in northern Pakistan. The knickpoints and their related geomorphic parameters (channel profile, concavity, drainage area, steepness index, etc.) were extracted from ASTER Digital Elevation Models (DEMs) with 30m resolution using ArcGIS, and Matlab software. A total of 251 knickpoints were extracted from the longitudinal profile of the Indus River along a ~750km long reach upstream of Tarbela dam. The identified knickpoint locations, along with their respective normalized steepness index (ksn values), were compared with the lithologic contacts, mapped faults, a regional level landslide inventory, and the locations of prehistoric rockslides. The knickpoints identified adjacent to the prehistoric landslide dams (i.e. Katzarah and Gol-Ghone events, and Lichar Gah etc.), exhibited normalized steepness index (Ksn) in the range of 500-1800m0.9 at various locations along the river channel. The highest normalized ksn values (>1800m0.9) were observed in the tectonically-active Nanga Perbat Haramosh Massif (NPHM) region, where the river flows through narrow gorges, and/or where active thrust faults cross the river channel. The study reveals that the landslide dams appear to be one of the significant trigger factors in the formation of knickpoints along the Indus River.

A review of conventional techniques for subsurface characterization of landslides

Naturally occurring landslides can be difficult to characterize and often exhibit anomalies in controlling geometry and consistency. The characterization of landslides in engineering geology practice is usually based on program of subsurface exploration; focused on identifying subsurface materials, structure and stratigraphy, hydrologic conditions, and appropriate strength parameters. On native slopes bereft of anthropogenic modification (excavation), geomorphic evidence of previous movement and its relative depth and scale are often discernible to the experienced eye. This paper seeks to describe the various techniques that have been successfully employed in site-specific subsurface investigations of prehistoric landslides. These include considerations of limiting geometry (for planning subsurface exploration and sampling), overcoming problems with site access, exploratory trenches, small diameter borings, downhole logging of large diameter borings, and geophysical techniques. These procedures can be combined to develop more realistic cross sections along the vector of maximum landslide movement, so the displaced mass can be realistically analyzed. The respective advantages and disadvantages of these techniques are discussed, with baseline references on subsurface exploration.

Morphological signatures of mass wasting and delta processes in a fjord-lake system: insights from Lovatnet, western Norway

High-resolution bathymetrical data from the Lovatnet lake, western Norway, reveal a diverse morphology including traces from historic and prehistoric landslides. Onshore LiDAR and selected seismic profiles support the interpretation. Our data from the lake show significant debris lobes below Ramnefjellet that was the source of the well-known rock avalanche and tsunami disasters in 1905 and 1936 which caused a total of 134 casualties. The debris is divided into three main lobes reaching a total length of 1.8 km along the lake bottom from the impact site, and diffuse lobe features below the Bodalsdelta. Frontal deformations are minor. Lobes on the basin plain have a volume of more than 1.2 × 10 6 m 3 including debris entrained from the surrounding slopes and lake floor. The entire lake volume was set in motion during the catastrophic events. Returning bottom flows transported debris into the lake where lobes and minor, distinct mounds were deposited up to c. 1.5 km from the lake's outlet.. The mounds could be of anthropogenic origin, and possibly include a vessel that disappeared. Erosion and smaller failures occurred elsewhere in the lake basin. Fan-delta morphologies are varied, with ridges and protuberances, reflecting a sedimentation pattern interrupted by mass-wasting or other events in the deltas and/or their catchments. This is especially clear for the Raudi, Hellsete and Bodalen deltas, but minor protuberances are also found in other deltas. The data also reveal traces from large and previously undocumented landslide events. Gravitational deposits generally dominate the steep slopes and glacial landforms are scarce. The study demonstrates the importance of linking onshore and offshore morphological datasets in order to obtain an overview over process variability in fjord-type lakes of importance for further investigation and hazard assessment.

An 825-year long varve record from Lillooet Lake, British Columbia, and its potential as a flood proxy

Lillooet River in southwest British Columbia has produced damaging floods many times during the past century. The floods are recorded in Lillooet Lake, into which the river flows, as anomalously thick clastic varves. In order to determine whether an 825-year long varve record obtained from 12 percussion and vibracores can be used as flood proxy, we compare river discharge records dating back to 1914 to the thickness of the varves deposited during the same time period. Correlations between varve thickness and a variety of historical discharge measures are low to moderate for the periods 1914–2004 (r2 = 0.37) and 1914–1945 (r2 = 0.40), but higher for the period 1946–2004 (r2 = 0.55). The best correlation (r2 = 0.55) is between maximum fall discharge and varve thickness during the most recent period (1946–2004). Varve thickness for the earlier period of hydrometric data (1914–1946), which is a time of rapid glacier retreat and warmer temperatures in British Columbia, is best explained with a discharge proxy combining nival runoff, glacier runoff, and maximum fall discharge. Landslides, glacier fluctuations, river dyking, artificial lowering of Lillooet Lake, as well as lag effects of storms are responsible for the considerable unexplained variance in the relation between discharge measures and varve thickness over the historic period. The cores contain many anomalously thick varves, some of which we attribute to previously dated prehistoric landslides in the watershed or to local landslides into the lake. We conclude that many historic and prehistoric floods are faithfully recorded as anomalously thick clastic varves, but that other processes operating in the watershed preclude using this record as a reliable paleo-flood proxy.

Characterizing a Landslide Hazard along the Wasatch Mountain Front (Utah)

Construction in mountainous areas of northern Utah is a concern due to landslide potential. As a result of dense vegetation and poor outcrops (from advanced weathering), the study of landslides along the Wasatch Mountain “Front” benefits from integrating geological and geophysical methods. We present a study of a Paleogene volcanic landslide along a portion of the Traverse Mountains. An integrated approach distinguishes an actual landslide from the weathered in situ volcanic rocks that mantle the area. We incorporate surface mapping, seismic methods, trenching, boreholes, and Light Detection And Ranging (LiDAR) to characterize the landslide. Our study reveals a faulted, chaotic body of variably altered block-and-ash flow tuffs. Multiple clay-lined shear planes and open fissures, now filled with soil, show that prehistoric landslides were focused within the altered block-and-ash flows. A major reflector lies at a depth of 80–100 m (262–328 ft) in seismic profiles, has an apparent dip of 4° to the south, and is approximately parallel to surface topography. The depth and character of this boundary indicate a contact between Paleogene volcanic rocks and underlying Paleozoic mixed siliciclastic and minor carbonate rocks. This unconformity may have acted as the slip surface for subsequent landsliding. The combination of weak block-and-ash flow tuffs and abundant clay alteration produced a body highly susceptible to multiple landslides. Using LiDAR and surface geology, discrete margins of the mapped landslide have been inferred in several areas. An integrated interpretation provides the range and resolution needed to assess the complex geology of such landslides.

Landslide susceptibility mapping of the Sea to Sky transportation corridor, British Columbia, Canada: comparison of two methods

The Sea to Sky corridor stretches over a distance of 135 km into British Columbia’s Coast Mountains. The corridor has witnessed hundreds of historical and pre-historic landslides. In the last 154 years, 155 landslide events have been reported. The most common types of landslides are rockfalls and debris flows, which are small in volume, but can be quite damaging. These are more abundant in the southern part of the corridor where infrastructure is built close to steep slopes. Two different methods were adapted to create debris flow and rockfall/rock slide susceptibility maps. Both qualitative heuristic and fuzzy logic susceptibility maps showed a similar distribution of susceptibility zones, especially high susceptibility. Correlation of high susceptibility zones with occurrence of historical and mapped geological landslide events was very good. Success rate curves were calculated for extrapolated zones of initiation for debris flow and rockfall/rock slide deposits. Success rate curves were better for debris flow than rockfall/rockslide maps.

Prehistoric landslide created hidden California lake

Prehistoric landslide created hidden California lake