Major Mass Movements Research Articles

Size-frequency distribution of submarine mass movements on the Palomares continental slope (W Mediterranean)

In this work, over 3620 km2 from the Palomares continental slope, which is located in the W. Mediterranean Sea, was analysed to quantify the impact of recent mass movements on this margin. A total of 936 landslides were identified, mapped and characterised by defining several morphometric variables that outline the accumulated impact of landslides equivalent to 918 km2 and 10.34 km3 of eroded sediment on the continental slope. The smallest event area was 0.0014 km2, whereas the largest event area was 32.48 km2. Smaller scars with a higher headwall gradient tend to dominate when the environment is steeper, and major mass movements are located on open slopes and structural highs. However, the slight or null correlations between variables indicate that a wide range of sizes may occur on any slope gradient and at any depth.The Palomares continental slope is intensively affected by mass movements. Compared with other passive margins (e.g., the U.S. Atlantic continental margin), landslides mobilised a limited amount of sediment, although it is comparable to other Mediterranean areas where small- to moderate-sized events are characteristic.The cumulative size distribution can be defined by a power-law function that describes events larger than 0.7 km2 with an exponent of α = 1.269. These results are consistent with those of other published inventories, including onshore cases. This result allows us to assume that the scale-invariant properties of the events are mapped. Scale-invariant properties can be explained by different models; self-organised criticality (SOC) is probably the most assumed by the scientific community, although alternative models may be nominated. Each model has important implications in terms of the landslide distribution and long-term landslide history of any slope. Alternative scenarios, such as submarine slopes, with more precise landslide inventories may contribute to new hazard assessment models that consider scaling exponents derived from size–frequency distributions.

Stability Analysis of a Landslide Scarp by Means of Virtual Outcrops: The Mt. Peron Niche Area (Masiere di Vedana Rock Avalanche, Eastern Southern Alps)

We investigated the Mt. Peron niche area of the Masiere di Vedana rock avalanche (BL), one of the major mass movements that affected the Eastern Southern Alps in historical times. So far, a geomechanical characterization and a stability analysis of the niche area, where potential rockfall sources are present, are lacking. The Mt. Peron niche area is a rocky cliff almost inaccessible to field-based measurements. In order to overcome this issue, we performed a geo-structural characterization of a sector of the cliff by means of a UAV-based photogrammetric survey. From the virtual outcrop, we extracted the orientation of 159 fractures that were divided into sets based on a K-means clustering algorithm and field-checked with some measurements collected along a rappelling descent route down to the cliff. Finally, with the aim of evaluating the stability of the volume under investigation, we performed a stability analysis of three rock pillars included in our survey by means of a distinct element numerical simulation. Our results indicate that two out of the three pillars are characterized by a stable state, under the simulation assumptions, whereas the third is close to failure, and for this reason, its condition needs further investigation.

Old but still active: > 18 ka history of rock slope failures affecting a flysch anticline

The Czech part of the Outer Western Carpathians (COWC) formed by flysch rocks is among the most landslide-prone areas in Europe. Recent LiDAR-based inventory mapping reveals that the area of the COWC encompasses more than 13,500 landslides, with some geological domains exhibiting > 20% of the surface area covered by landslides. Although mass movements represent crucial geomorphic agents in the COWC, their timing and especially lifespan remain elusive. In this study, we focused on rockslides affecting the flanks of the flysch anticline developed within Paleogene sandstones. The area (“Hradisko” ridge) is well known as the most extensive rock city in the COWC. Structural-geological investigation, kinematic analysis and the application of near-surface geophysics (ERT, GPR and seismic refraction) suggest that rockslides accompanied by toppling and lateral spreads are predisposed by the architecture of bedding planes, joints and inherited faults cross-cutting the anticlinal ridge. Based on 10Be exposure dating of five scarps and rockslide boulders (a total of 25 cosmogenic-dated samples), we were able to reconstruct the long-term history of rock slope failures. Although the obtained ages of headscarp exposures reveal consistent patterns suggesting major mass movement phases at ~ 18 ka and ~ 12 ka, the interpretation of boulder exposure ages is ambiguous. The study area has not been affected by catastrophic slope failure in historic times, but dendrogeomorphic analysis reveals surprisingly strong tree ring signals of mass movements within the last 150 years. These findings suggest that progressive failure is developing within some parts of the rockslide and/or slope portions above the major scarp. We conclude the following: (1) some rockslide spots within the COWC might express a very long history, encompassing the full Late Glacial–Holocene Period; (2) major mass movement activity in the study site temporally coincided with the major climatic changes; (3) rockslides with a very long history still represent potential hazards, although evidence of their active movement is not detected by standard geomorphic mapping techniques and (4) dating of the scarps should be preferred as even a higher number of boulders might be unreliable.

Dynamic movement history of the Iiyama slope failure revealed from seismic data

The Iiyama slope failure occurred in the early morning of May 19, 2017, in Nagano Prefecture, central Japan. It caused a debris flow in the Idegawa River, resulting in the evacuation of the residents of the neighboring areas for half a year. Since the source was located in a mountainous area, the cause of the debris flow was not discovered immediately.To investigate the mechanism of this slope failure, we performed a field survey and obtained aerial photos of the slope failure using an unmanned aerial vehicle. Additionally, we analyzed seismic data recorded by the surrounding stations, to identify the ground motion generated by the mass movements.We found that the Iiyama slope failure involved two major mass movements: a large landslide and a subsequent debris flow triggered by the landslide. The movement of the landslide was recorded with long-period seismic waveforms, and the estimated force history showed a unidirectional movement from north to south for 50 s, reaching a maximum velocity of about 6.6 m/s. Following, debris flew for about 5 km from the top of the landslide source area. The initial collapse produced a large shaking with a short-period component, and the signal gradually decayed as the debris flow traveled along the river.Our study shows that the two mass movements in the Iiyama slope failure generated ground motions with completely different frequencies. This suggests that the ground motions recorded by the seismometer are significant for understanding the movement mechanism of slope failure. The seismic signal, combined with the aerial photos, helps us to understand the dynamic movement history of the landslide.

Landslide inventory map of the tropical dry Sierra Costa Region, Michoacán México

ABSTRACTIn the framework of a landslide inventory map of the Sierra Costa Region, we identified and classified landslides on the basis of extensive field-verified aerial photo interpretation. Geological and geomorphological data were gathered to assess the spatial distribution of the landslides, occurrence characteristics and possible associated risk. Of the 1262 landslides analysed and classified, the main geomorphological units for landslide occurrence were fluvial valleys located in the mountains (1007 landslides) and in the rolling hills (260 landslides). Debris flows were mostly controlled by lithological contacts (478 landslides) and slope gradient (367 landslides); debris slides were mainly influenced by lithological features, more specifically sedimentary rocks (208 landslides). Another significant factor was fault systems associated with fluvial valleys (92 landslides). The identification, location and classification of major mass movement types, in combination with the assessment of controlling factors, allow us to understand the nature of slope instability in the region and contribute to land planning efforts.

Timing and features of a late MIS 2 rock avalanche in the Eastern Himalayas, constrained by 10Be exposure dating

We investigate a previously unrecorded rock avalanche deposit (Yadong rock avalanche) that resulted from a major mountain slope failure on the northwest slopes of Mt. Chomo Lhari in the Eastern Himalayas. We provide detailed mapping of the Yadong rock avalanche, and date the rock avalanche using 10Be surface exposure dating. The 10Be exposure ages of six samples suggest that the Yadong rock avalanche occurred between 14.2 ± 1.3–13.1 ± 1.3 ka during the Bølling-Allerød (BA) period. The climate was semi-arid during the BA period as it is today, which suggests that precipitation was unlikely the trigger for this rock avalanche. The relatively small paleo glaciers make glacial debuttressing trigger unlikely. Since the rock scar is situated above the lower permafrost limit, degradation of permafrost associated with deglaciation was also unlikely to be the trigger. Given the rock avalanche is located near the Yadong fault which is part of the active Yadong-Gulu rift, and the Yadong-Gulu rift has experienced great earthquakes on centennial to millennial timescales, we suggest that the most probable trigger for this rock avalanche was a seismic event associated with the Yadong fault. The result provides evidence for identifying a paleo seismic event occurred during 14.2 ± 1.3–13.1 ± 1.3 ka. These findings have important implications for understanding the mechanisms for driving rock avalanches and associated landscape evolution across the Himalayas, as well as for extending the limited scientifically documented records of major mass movements in the Eastern Himalayan region.

Morphological analysis and features of the landslide dams in the Cordillera Blanca, Peru

Global warming in high mountain areas has led to visible environmental changes as glacial retreat, formation and evolution of moraine dammed lakes, slope instability, and major mass movements. Landslide dams and moraine dams are rather common in the Cordillera Blanca Mountains Range, Peru, and have caused large damages and fatalities over time. The environmental changes are influencing the rivers’ and dams’ equilibrium, and the potential induced consequences, like catastrophic debris flows or outburst floods resulting from dam failures, can be major hazards in the region. The studies of past landslide dam cases are essential in forecasting induced risks, and specific works on this topic were not developed in the study region. Reflecting this research gap, a database of 51 cases and an evolution study of landslide dams in the Cordillera Blanca Mountains is presented. The main morphometric parameters and information of the landslide, the dam body, the valley, and the lake, if any, have been determined through direct and indirect survey techniques. Low variability in some of the main morphometric parameter distributions (valley width and landslide volume) has been shown, most likely due to an environmental control connected to the regional tectonic and glacial history. In order to analyze present and future landslide dam evolution, a morphological analysis was carried out using two recently developed geomorphological indexes employed on the Italian territory. The results of the Cordillera Blanca analysis have been compared with a large Italian landslide dam inventory, highlighting as much the differences as the similarities between the two datasets. The long-term geomorphological evolution changes are evaluated. Many of the stable dams are in disequilibrium with their surrounding environment and their classification result is of “uncertain determination.”

Geomorphic Processes, Rock Quality and Solid Waste Management—Examples from the Mt. Everest Region of Nepal

Sagarmatha National Park and Buffer Zone (SNPBZ) in the Everest region in Nepal is among the most popular destinations for trekking tourism in Nepal. The dramatic growth of the tourism industry has increased pressures on the environment and the National Park is heavily affected by the rapidly growing waste issue. Besides, major mass movements play an important role in the Himalaya and have been observed in SNPBZ. Also, seasonal monsoon floods, debris flows, rock falls, landslides and the creation of glacial lake outburst floods are frequently occurring in the region. This paper explores the reciprocal interactions between the geo-environment and solid waste management in Everest’s SNPBZ. Therefore, geological characteristics and geomorphological processes, especially the two large rockslides in Lukla and Khumjung, as well as their consequences for rock quality, climatic and hydrologic conditions, are analyzed and simultaneously connected to the rapidly growing tourism-induced waste issue. Rockslide material shows high porosity and permeability. Thus, we argue that rockslide facies are particularly vulnerable to contamination by waste water and washed out agricultural fertilizers, which pose threats to the population especially in Namche Bazaar but probably also in Lukla. Also, the landfill sites are often affected by geomorphological processes and may consequently contaminate surface and ground water. Results highlight that regional infrastructure planning of landfill sites often collides with the natural features of the geo-environment and often causes harm to human health and the environment. The implications of the results can be applied to similar areas (such as Marsyandi Valley, Kali Gandaki Valley) with special geological characteristics and rapidly growing waste issues.

President Obama, the Tea Party Movement, and the Crisis of the American Party System

This paper examines the reasons that, in the US, the first major mass movement in response to the economic crisis that began in 2007 was from the right, and assesses the possibility that the labor protests in Madison WI in the winter of 2011 may be the beginning of a similar movement on the left.

Megaturbidite deposits in the Holocene basin fill of Lake Como (Southern Alps, Italy)

For the first time, limnogeological investigations have been carried out in Lake Como, the deepest lake of the Alps, combining a bathymetric survey (multibeam Simrad 3000) with a high-resolution seismic reflection study (single-channel 3.5 kHz sub-bottom profiler) and a coring campaign (gravity corer). This data set enables detailed characterization of the sedimentary subsurface in the western branch of the lake, the Como branch, which has a typical fjord morphology. This paper focuses on the deepest part of the Como branch (Argegno basin), in which up to 3.5-m-thick turbidite deposits are identified. The basin fill of the Como branch is characterized by well-layered draping and onlapping pelagic sediments that are locally affected by creeping and that are intercalated with mass-wasting deposits, in particular with two large debris-flow deposits evolving into megaturbidites in the deepest part of the basin. The multibeam data together with the acoustic-facies distributions and the volumes of these two major sedimentary deposits MT1 (∼ 3 × 10 6 m 3) and MT2 (∼ 10.5 × 10 6 m 3) indicate that they resulted from large slides at the northern tip of the Como branch along the steep slopes of a sub-lacustrine plateau. The estimated ages of these events, around the mid-12th (MT1) and early 6th (MT2) centuries, are extrapolated from mean sedimentation rates based on radiocarbon ( 14C) and radionuclide ( 137Cs) analyses from short cores in the Argegno basin. Possible trigger mechanisms leading to these catastrophic events in the Como branch include a combination of steep-slope overloading, with significant lake-level fluctuations related to Holocene climate change and/or earthquake shaking. The tentative age assignment places the age of both major mass movements near two other events: MT1 near the occurrence of a major earthquake in the Po Plain in 1222 AD (Intensity IX MCS, macroseismically derived magnitude 6.2) and MT2 near a megaturbidite triggered in ∼ 700 AD in a proglacial lake in southeastern Switzerland [Blass, A., Anselmetti, F., Grosjean, M., Sturm, M., 2005. The last 1300 years of environmental history in the sediments of Lake Sils (Engadine, Switzerland). Eclogae Geologicae Helvetiae 98, 319–332]. Since dangerous, tsunami-like waves (seiches) can be generated by large sub-aqueous landslides leading to such megaturbidites in this fjord-like basin, future studies are required: 1) to constrain the age of these catastrophic events; 2) to document the stabilities of the steep slopes in the Como branch, 3) to assess the expected frequency of such catastrophic events and 4) to model the propagation of large waves in the Como branch and their potential damage along the highly populated lake shore.

Predesign, failure and displacement mechanisms of large rockslides in the Annapurna Himalayas, Nepal

The paper analyses and compares four major mass movements (rockslides and rock avalanches) with volumes of 1 to 5 km 3 around the Annapurna Himalayan region from engineering, geological, quaternary geological, and geomorphological viewpoints. It shows how paleotectonic and neotectonic predesign, as well as morphological overprint caused by glacial activities, are the main preparatory causal factors for the sliding events. That is why giant failures of mountain crests have mainly occurred in areas of tectonic activity. The mechanism of failure, and displacement of the resulting large mass movements also strongly depends on this litho-tectonic predesign and continues in giant translational rockslides in which the primary rock structure or fabric is preserved, but shattered by mechanical stress during the sliding event.

Multiple landslide clusters record Quaternary climate changes in the northwestern Argentine Andes

The chronology of multiple landslide deposits and related lake sediments in the semi-arid eastern Argentine Cordillera suggests that major mass movements cluster in two time periods during the Quaternary, i.e. between 40 and 25 and after 5 14C kyr BP. These clusters may correspond to the Minchin (maximum at around 28–27 14C kyr BP) and Titicaca wet periods (after 3.9 14C kyr BP). The more humid conditions apparently caused enhanced landsliding in this environment. In contrast, no landslide-related damming and associated lake sediments occurred during the Coipasa (11.5–10 14C yr BP) and Tauca wet periods (14.5–11 14C yr BP). The two clusters at 40–25 and after 5 14C kyr BP may correspond to periods where the El Niño–Southern Oscillation (ENSO) and Tropical Atlantic Sea Surface Temperature Variability (TAV) were active. This, however, was not the case during the Coipasa and Tauca wet periods. Lake-balance modelling of a landslide-dammed lake suggests a 10–15% increase in precipitation and a 3–4°C decrease in temperature at ∼30 14C kyr BP as compared to the present. In addition, time-series analysis reveals a strong ENSO and TAV during that time. The landslide clusters in northwestern Argentina are therefore best explained by periods of more humid and more variable climates.

Climate change and mass movements in the NW Argentine Andes

The chronology of multiple landslide deposits and related lake sediments in the eastern Argentine Cordillera suggests that major mass movements cluster in two time periods during the Quaternary: between 35 000 and 25 000 14C yr BP and after 5000 14C yr BP. The older cluster may correspond to the Minchin wet period (40 000 and 25 000 14C yr BP) identified in tropical and subtropical South America, suggesting a causal relation between enhanced landslide activity and climate change. The younger cluster predates the Titicaca wet period that began at about 3900 14C yr BP which also affected other regions in the Andes and the Amazon Basin. No landslide and associated lake sediments are documented during the Tauca wet period (between 16 000 and 8000 14C yr BP). However, the two clusters correspond to periods where it assumed that the El Niño/Southern Oscillation (ENSO) and tropical Atlantic sea surface temperature dipole (TAD) were active. The analysis of the present-day precipitation patterns in NW Argentina indicates significant spatial and temporal differences between the intra-Andean part of the study area and the Andean foreland. Whereas the TAD seems to consistently increase rainfall, the intensity of precipitation during the El Niño phase of the ENSO is reduced to only 25% of the mean annual average in the intra-Andean basins, whereas the regions east of the Andes receive more than 125%. Similar results, but with an opposite sign, characterize La Niña events. The comparison of this pattern with paleo-precipitation data as inferred from varved lake sediments suggests that increased interannual climate variability and, therefore, increased fluctuations in rainfall and river discharge in narrow valleys may reduce landsliding thresholds.

MAPPING OF LANDSLIDE HAZARD ZONES IN JORDAN USING REMOTE SENSING AND GIS

Preliminary studies are required before the construction of a highway in order to meet certain objectives, such as low cost, accessibility to urban facilities, compatibility with land use, efficient use of resources, and stability of hill slopes. For stability of hill slopes, a landslide hazard zonation map should be prepared so as to select proper road alignment, in order to provide quantitative measures to be taken by the designer in unstable, hazard-prone areas. Preparation of such a map involves handling a huge amount of data, and it can be done in either of two ways: manually or using computer software such as a geographic information system (GIS). A GIS technique is employed in this study to integrate the instability factors. The intersection of these factors using this technique enables users to classify an area into zones of varying degrees of instability. An area of approximately 1,300 sq km divided into 1,603,000 pixels along the Amman-Irbid highway was chosen for this study. Between 1966 and 1971, four major mass movements took place, and in 1991/1992 seven more major landslides occurred along the same highway at a time when it was under reconstruction and expansion. The main objective of this paper is to report on the integration of spatial data for the purpose of establishing a mass movement hazard zoning map using a GIS. To fulfill this objective, a structural model was developed. It was built in two consecutive stages. The first stage consists of transformation of data collected and a first-step integration of spatial data to delineate the major causative factor maps. In the second stage, a stepwise sequence of integration was performed to combine all the maps obtained in the first stage. The results obtained from the landslide hazard zoning map agree well with the landslides observed in the field.

Late Quaternary mass movement on the lower continental rise and abyssal plain off Western Sahara

ABSTRACTThe late Quaternary development of part of the lower continental rise off Western Sahara has been determined from an investigation of short (< 2 m) gravity cores collected from a deep‐sea channel, the interchannel areas and an abyssal hill, between 30 and 33°N. Stratigraphic analysis is based on systematic variations in abundances of particular coccolith species and pelagic sediment types, referenced to the oxygen isotope time‐scale. During the last 73 000 years deposition in the channel has included volcaniclastic sand/silt turbidites and minor marl turbidites as well as pelagic sediments. The interchannel area has fewer turbidites, and the sands present were probably deposited from turbidity currents which spilt over the channel sides. The last‘event’ to give rise to sands in the channel and interchannel area occurred about 45 000 years ago. Although the channel has been inactive as an area of turbidity current deposition for the last 20 000 years, sands were deposited elsewhere on the lower rise, indicating that turbidity current transport routes have varied in time.Turbidity current deposition on the abyssal plain and low‐lying continental rise appears to be related to distinct sliding events involving transport of material from various sources. Thin marl turbidites are interbedded with pelagic sediments in the area of sediment drape. There is a strong correlation between these and the thick marl turbidites on the abyssal plain, suggesting that the same turbidity current‘events’, occurring about once every 25 000 years, gave rise to both sets of deposits. The thinner units probably represent deposition from the outer parts or tails of the large turbidity flows. The turbidites occur at glacial/interglacial transitions, suggesting that the slides that created them were triggered by mechanisms related to climatic change. Several volcaniclastic sand/silt units within the channel and in interchannel areas occupy mid‐stage stratigraphic positions, perhaps indicating a different triggering mechanism for slides around volcanic islands. A debris flow deposit (debrite), between 30°N, 21°W and 31°N, 24°W, is related to the Saharan Sediment Slide, a major mass movement feature on the continental slope over 1000 km to the southeast. Stratigraphic correlations indicate that this slide produced a large turbidity current as well as a debris flow.

Holocene Sediment Budgets for the Basins of the California Continental Borderland

ABSTRACT Two Holocene sediment budgets have been compiled for the California Continental Borderland. The first detailed budget includes the six northern inshore and central basins that capture almost 40% of the total sediment input to the entire borderland. In the second budget, the data for the six basins has been added to estimates of accumulation for the remaining borderland area to produce a total regional budget of lower precision than the smaller, six-basin region. Natural river influx to the borderland approximates 13 1010 tons for the Holocene epoch, and biological input has been estimated at about 2 1010 tons. Eolian and ocean current influx have each been estimated at about 1 1010 tons. In sum, the total deposited volume for 104 yrs is about 14 1010 tons, and the estimated total influx is of the order of 17 1010 tons, which suggests that a net of 1-3 101010 tons for the Holocene high sea-level period. The six high-accumulation-rate basins are located adjacent to the largest river sources, the major zones of coastal upwelling, and the main northern eddies of the California Current. These high-accumulation sites are typically also areas where mass movement and fan development are localized. The sediment-accumulation rate is much larger than subsidence rate, and flat-floored basins are typical. In contrast, the southern and outer, low-accumulation basins are areas of draped sediment, with accumulation rate less than subsidence rate, and are the sites of penecontemporaneous deformation of the accumulating, fine hemipelagic sediments. Few fans or major mass movements are seen. Significant sedimentation is mainly confined by topography to less than 20% of total margin area. Thus, the moderate to low total sediment influx is amplified by the restricted receiving area to produce locally thick deposits of limited areal extent. This pattern is characteristic of Neogene southern California basins and illustrates that stratigraphic thickness is not a valid indicator of sediment influx.

The Incidence of Landslides, Avalanches, and Floods in Western Norway during the Little Ice Age

Land rent assessments from western Norway and floods which started in the late 17th centand documents concerned with applications for ury and continued into the 19th century in their reduction provide detailed information valleys adjacent to Jostedalsbre. This environabout the incidence of landslides, rockfalls, mental change began abruptly and there was a and avalanches, as well as floods, during the striking concentration of disastrous incidents period of the Little Ice Age. The nature and between 1650 and 1760 and in certain years reliability of the available data is discussed and during that period, such as 1687, 1693, and is shown to be adequate to demonstrate a much 1702. increased incidence of major mass movements