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This study employs statistical modeling techniques and geomorphological mapping to analyze the distribution of debris-rockslides in relation to altitude, aspect, slope angle, lithology and distance to lineaments using optical remote sensing techniques with GIS. The study area includes a portion of the Central Precordillera of San Juan around 32°S, 69°W, where few geomorphological studies have been conducted. A debris-rockslides inventory map was prepared using debris-rockslides locations identified from satellite imageries, a total of 35 debris-rockslides were identified in an area of 288.13 km 2 (with a total slide area of 6.36 km 2 ). All of the debris-rockslides were rotational slides, affecting Upper Ordovician and Upper Devonian deposits. The volumes of debris-rockslides were estimated using the sloping local base level technique that allows computing the possible pre-rockslide topography and the bedrock–deposits interface. The relationship between the variables and the slide distribution was analyzed using the frequency ratio method and logistic regression models. The analytical results show that lithology and slope exert major influences. Lithology is found to be the most important aspect in the study area. [ABSTRACT FROM AUTHOR]

A new Burgess Shale-type Lagerstätte is described from the middle Cambrian (Series 3, Drumian) Rockslide Formation of the Mackenzie Mountains, Northwest Territories, Canada. The Rockslide Formation is a unit of deeper water ramp to slope, mixed carbonate, and siliciclastic facies deposited on the northwestern margin of Laurentia. At the fossil-bearing locality, the unit onlaps a fault scarp cutting lower Cambrian sandstones. There it consists of a succession of shale and thick-laminated to thin-bedded lime mudstone, calcareous sandstone, and greenish-colored calcareous mudstone, overlain by shallower water dolostones of the Avalanche Formation, which is indicative of an overall progradational sequence. The Rockslide Formation is of similar age to the Wheeler and Marjum formations of Utah, belonging to the Bolaspidella Biozone. Only two 1 m thick units of greenish mudstone exhibit soft-bodied preservation, with most specimens coming from the lower interval. However, the biota is common but not as diverse as that of other Lagerstätten such as the Burgess Shale in its type area. The shelly fauna is dominated by the hyolith Haplophrentis carinatus Matthew, 1899 along with sparse linguliformean brachiopods, agnostoid arthropods, and ptychoparioid trilobites. The nonmineralized biota includes the macrophytic alga Margaretia dorus Walcott, 1911, priapulid worms, and the carapaces of a number of arthropods. The arthropods belong to Isoxys mackenziensis n. sp., Tuzoia cf. T. guntheri Robison and Richards, 1981; Branchiocaris? sp., Perspicaris? dilatus Robison and Richards, 1981; and bradoriids, along with fragments of arthropods of indeterminate affinities. The style of preservation indicates that most soft parts underwent complete biodegradation, leaving just the more resistant materials such as chitinous arthropod cuticles. The range of preservation and similarity to the coeval biotas preserved in Utah suggests that the composition of this Lagerstätte is probably representative of the community living on the relatively deep-water ramp or slope during middle Cambrian time in Laurentia. This would argue that the extraordinary diversity of the Burgess Shale at Mount Field is anomalous. [ABSTRACT FROM AUTHOR]

The distribution of late Pleistocene to Holocene rockslides in the western flank of the eastern mountain ranges of Central Precordillera (30° 40′–31° S), has been analyzed to determine the triggering mechanisms. The mode of failure was determined to be translational sliding. This paper presents the results of research on one of the Holocene rockslides located in the western flank of Sierra de La Dehesa, which is composed of stratified limestones of early Paleozoic age. In order to characterize this slide, high resolution satellite imagery interpretation was carried out, along with the recognition of the landslide detachment zones and landslide bodies with the aim of reconstructing the pre-slide topography. The model proposed for this slide is a translational or planar slide, as the mode of failure was along a broadly planar surface accompanied by shear or tensile fractures and joints. The estimated rock volume involved is 1.24 Mm 3 . We compared rockslide occurrence patterns to slope, topography, lithology, geological structures, and seismicity records. After analysis of the spatial relationships among all the slides and the distribution of seismic epicenters, historical earthquakes and neighboring Quaternary faults as seismogenic sources, we hypothesize that these Quaternary rockslides in the Central Precordillera have been triggered by shallow seismicity associated with active faults. [ABSTRACT FROM AUTHOR]

Complex large landslides are characterized by different kinematic behaviors and involve diverse materials. Both elements make it difficult to study the instability of these huge mass movements, which may cause massive damage and affect extended areas. This paper is focused on the study of Spriana landslide, an important rockslide located in the North of Italy. Starting from the geological interpretation provided by Belloni and Gandolfo (Geologia tecnica ed ambientale 3:7-36, ), the authors gather all available data sets and perform a novel analysis aimed to better describe the unstable body. The key point of this case study regards the characterization of the deeper surface of failure. The location as well as the continuity of this surface is a crucial unsolved question, and in this paper we try to provide a reasonable answer. We propose a new hypothesis based on a structurally controlled, wedge-like rockslide involving the presence of a composed deeper surface of failure constrained by the intersection of two different weak zones. Although this work mainly addresses the development of a new geological model, numerical simulations were also performed. Both continuous and discontinuous models were tested, and then a comparison of the outcomes of the numerical simulations was performed to define the best fit to the observed landslide behavior. [ABSTRACT FROM AUTHOR]

We completed a systematic mapping of landslides in a 10 5 km 2 area in Tithonium and Ius Chasmata, Valles Marineris, Mars, where landslides are abundant. Using visual interpretation of medium to high-resolution optical images, we mapped and classified the geometry of 219 mass wasting features, including rock slides, complex/compound failures, rock avalanches, debris flows, and rock glacier-like features, for a total landslide area of A LT = 4.4 × 10 4 km 2 , 44% of the study area, a proportion larger than previously recognised. Studying the landslide inventory, we showed that the probability density of landslide area p ( A L ) follows a power law, with a scaling exponent α = − 1.35 ± 0.01 , significantly different from the exponents found for terrestrial landslides, α = − 2.2 and α = − 2.4 . This indicates that the proportion of large landslides ( A L > 10 7 m 2 ) is larger on Mars than on Earth. We estimated the volume ( V L ) of a subset of 49 deep-seated slides in our study area and found that the probability density of landslide volume p ( V L ) obeys a power law trend typical of terrestrial rock falls and rock slides, with a slope β = − 1.03 ± 0.01 . From the combined analysis of landslide area and volume measurements, we obtained a power law dependency comparable to a similar relationship obtained for terrestrial bedrock landslides, V L = ( 1.2 ± 0.8 ) × A L ( 1.25 ± 0.03 ) . From the fall height H L and run out length L L of a subset of 83 slides unaffected by topographic confinement, we obtained the mobility index (Heim's ratio) H L / L L , a measure of the apparent friction angle of the failed materials, ϕ = 14.4 ° ± 0.4 ° . Slope stability simulations and back analyses performed adopting a Limit Equilibrium Method, and using Monte Carlo approaches on failed and stable slopes, suggest that the large landslides in Valles Marineris were seismically induced. [ABSTRACT FROM AUTHOR]

The Marboré Cirque, which is located in the southern Central Pyrenees on the north face of the Monte Perdido Peak (42°40′0″N; 0.5°0″W; 3355 m), contains a wide variety of Holocene glacial and periglacial deposits, and those from the ‘Little Ice Age’ (‘LIA’) are particularly well developed. Based on geomorphological mapping, cosmogenic exposure dating and previous studies of lacustrine sediment cores, the different deposits were dated and a sequence of geomorphological and paleoenvironmental events was established as follows: (1) The Marboré Cirque was at least partially deglaciated before 12.7 kyr BP. (2) Some ice masses are likely to have persisted in the Early Holocene, although their moraines were destroyed by the advance of glaciers during the Mid Holocene and ‘LIA’. (3) A glacial expansion occurred during the Mid Holocene (5.1 ± 0.1 kyr), represented by a large push moraine that enclosed a unique ice mass at the foot of the Monte Perdido Massif. (4) A melting phase occurred at approximately 3.4 ± 0.2 and 2.5 ± 0.1 kyr (Bronze/Iron Ages) after one of the most important glacial advances of the Neoglacial period. (5) Another glacial expansion occurred during the Dark Age Cold Period (1.4–1.2 kyr), followed by a melting period during the Medieval Climate Anomaly. (6) The ‘LIA’ represented a clear stage of glacial expansion within the Marboré Cirque. Two different pulses of glaciation were detected, separated by a short retraction. The first pulse occurred most likely during the late 17th century or early 18th century (Maunder Minimum), whereas the second occurred between 1790 and ad 1830 (Dalton Minimum). A strong deglaciation process has affected the Marboré Cirque glaciers since the middle of the 19th century. (7) A large rock avalanche occurred during the Mid Holocene, leaving a chaotic deposit that was previously considered to be a Late Glacial moraine. [ABSTRACT FROM PUBLISHER]

Rockslides in alpine areas can reach large volumes and, owing to their position along slopes, can either undergo large and rapid evolution originating large rock avalanches or can decelerate and stabilize. As a consequence, in particular when located within large deep-seated deformations, this type of instability requires accurate observation and monitoring. In this paper, the case study of the La Saxe rockslide (ca. 8 × 10 m), located within a deep-seated deformation, undergoing a major phase of acceleration in the last decade and exposing the valley bottom to a high risk, is discussed. To reach a more complete understanding of the process, in the last 3 years, an intense investigation program has been developed. Boreholes have been drilled, logged, and instrumented (open-pipe piezometers, borehole wire extensometers, inclinometric casings) to assess the landslide volume, the rate of displacement at depth, and the water pressure. Displacement monitoring has been undertaken with optical targets, a GPS network, a ground-based interferometer, and four differential multi-parametric borehole probes. A clear seasonal acceleration is observed related to snow melting periods. Deep displacements are clearly localized at specific depths. The analysis of the piezometric and snowmelt data and the calibration of a 1D block model allows the forecast of the expected displacements. To this purpose, a 1D pseudo-dynamic visco-plastic approach, based on Perzyna's theory, has been developed. The viscous nucleus has been assumed to be bi-linear: in one case, irreversible deformations develop uniquely for positive yield function values; in a more general case, visco-plastic deformations develop even for negative values. The model has been calibrated and subsequently validated on a long temporal series of monitoring data, and it seems reliable for simulating the in situ data. A 3D simplified approach is suggested by subdividing the landslide mass into distinct interacting blocks. [ABSTRACT FROM AUTHOR]

A 12 million of m translational rockslide developed on a dip slope underlain by limestone with interlayered marls, and responsible for the destruction of the Montclús village in the fourteenth century, has been investigated by means of geomorphological and geophysical surveys. The combination of historical-geoarcheological, geomorphological, seismic refraction and electrical resistivity imaging datasets allowed the (1) reconstruction of the late Quaternary episodic evolution of the landslide, (2) characterization of the geometry and internal structure of the slid mass and (3) identification of preferential groundwater flow paths that favoured slope instability. The development of the landslide involved at least two different displacement episodes controlled by sliding surfaces at successively deeper stratigraphic positions. The first landsliding event, recorded by highly weathered landslide deposits situated above a perched failure plane, occurred approximately during the global Last Glacial Maximum (23-19 ka BP). The most recent event, which destroyed the Montclús village built on already slid rocks, is placed in the fourteenth century. Most probably, this reactivation event was triggered by the 1373 Ribagorza earthquake, with an estimated moment magnitude of M 6.2. This work illustrates the benefits of combining geomorphological data with complementary geophysical technics in landslide investigation. [ABSTRACT FROM AUTHOR]

Uplifting mountains are denudated by gravitational deformation, landslides, and glacial or fluvial erosion. We investigated the response of valley slopes to glacial and fluvial erosion along the Kali Gandaki (KG) River, one of the largest rivers that flows through the High Himalaya southward from Tibet to India and diagonally cuts the strikes of gneiss and slate foliations. Satellite images with 2.5 m resolution and 5-m Digital Elevation Models (DEMs) were used for the investigation. Within a 20-km reach of the KG River, we found a series of 11 landslides, which vary from a total area of 0.58 to 12 million m2 each. The foliations generally strike NW–SE and dip at 30° to 50° to the NE, so the left bank slopes are anaclinal and the right bank slopes are cataclinal. On the cataclinal slopes, buckling of beds occurs, and gradual deformation proceeds in slate and two-mica gneiss, while in the more competent calc gneiss, buckling deformation develops into a rock avalanche. Such rock avalanches are represented by the largest Dhampu-Chhoya landslide, which once blocked the KG River and drastically changed the river morphology. Anaclinal slopes of two-mica gneiss were toppled and transformed into rock avalanches on three slopes. The KG River has a prominent fluvial knickpoint, which is currently at an elevation of 1800 m, and it has slope breaks on the left bank that are 200–400 m above the riverbed downstream of the knickpoint. Toppling was observed on slopes higher than slope breaks, which suggests that toppling began before the formation of slope breaks by fluvial incision and that the lower slopes did not adapt to the younger fluvial incision. In contrast, slope breaks are scarcely found on the right bank, probably because slow-moving DGSDs, which followed the river incision, erased them. • The Himalayan mountains respond to erosion based on geological structures. • Buckling and gradual deformation proceed on dip slopes of incompetent rock. • Buckling of competent rock develops into catastrophic failure. • On anaclinal slopes, toppling and catastrophic failure occur. • Upstream migration of a fluvial knickpoint induced a series of mass movements. • Glacial erosion and deglaciation destabilized the feet of dip slopes, inducing buckling deformation. [ABSTRACT FROM AUTHOR]

An unstable rock volume of more than 50millionm3 has been detected in the Åkerneset rock slope in the narrow fjord, Storfjorden, Møre & Romsdal County, Western Norway. If large portions of the volume are released as a whole, the rockslide will generate a tsunami that may be devastating to several settlements and numerous visiting tourists along the fjord. The threat is analysed by a multidisciplinary approach spanning from rock-slope stability via rockslide and wave mechanics to hazard zoning and risk assessment. The rockslide tsunami hazard and the tsunami early-warning system related to the two unstable rock slopes at Åkerneset and Hegguraksla in the complex fjord system are managed by Åknes/Tafjord Beredskap IKS (previously the Åknes/Tafjord project). The present paper focuses on the tsunami analyses performed for this company to better understand the effects of rockslide-generated tsunamis from Åkerneset and Hegguraksla. Two- and three-dimensional site-specific laboratory experiments are conducted to study the generation, propagation, and run-up of the wave for several potential rockslide scenarios from Åkerneset. Furthermore, the two models GloBouss and DpWaves are applied for numerical simulations of the generation/propagation phase and a third model MOST is applied for numerical simulations of the near-shore propagation and inundation of the wave in selected locations. Strong emphasis is put on verification, validation, and sensitivity of the numerical models. The best match between the numerical simulations and the laboratory experiments is found for the larger scenarios with the linear dispersive solution for the propagation phase; the corresponding calculated run-up values are remarkably similar to the ones observed during the laboratory experiments. During the risk assessment it was found that the rockslide tsunami hazard (probability of impact) is higher than accepted by the Norwegian Planning and Building Act. This should at that time prevent any further development in all the exposed areas of the entire fjord system. The Act is today altered to open for specified further development in the various hazard zones. The results of the tsunami analyses are applied in risk management in terms of hazard map production and land-use planning. Two failure scenarios for each of the two unstable rock slopes are designed for the hazard zoning. The larger and less probable scenarios (1 in 5000years) are applied for evacuation zones and routes, while the smaller and more probable scenarios (larger than 1 in 1000years) are applied for location and design of less critical facilities accepted in the inundation zone. [ABSTRACT FROM AUTHOR]

Abstract: Landslide seismic signal processing and the Newmark's sliding block analysis are used in this research to analyze the initiation time and mobility of the Tsaoling rockslide triggered by the 1999 Chi-Chi Earthquake in Central Taiwan. A new technique, the time–frequency spectrum analysis, is employed to identify the rockslide initiation and landing times from four real time seismic records of strong ground motion stations. The results suggest that higher frequencies ranging from 30 to 70Hz correspond to the rockslide initiation and sliding process, which are opposed to the low signal frequency of earthquake. The landslide began at 32.5s, the sliding block sped up at 37.5s, and impacted on the opposite riverbank at 76s on the seismic time record. The mobile scenario of Tsaoling rockslide induced by Chi-Chi Earthquake is simulated using Newmark's sliding block analysis. The maximum sliding velocity reaches approximately 75.1m/s. Despite being a simple conceptual model, the Newmark's sliding block analysis provides consistent results with the real time seismic signal analysis and details of the rockslide kinematics. [Copyright &y& Elsevier]

Abstract: The growing body of research on large-scale mass wasting events so far has only scarcely investigated the sedimentology of chaotic deposits from non-volcanic terrestrial landslides such that any overarching and systematic terminological framework remains elusive. Yet recent work has emphasized the need for better understanding the internal structure and composition of rockslide deposits as a means to characterise the mechanics during the final stages of runout and emplacement. We offer a comprehensive overview on the occurrence of rock fragmentation and frictional melt both at different geographic locations, and different sections within large ( ) rockslide masses. We argue that exposures of pervasively fragmented and interlocked jigsaw-cracked rock masses; basal mélange containing rip-up clasts and phantom blocks; micro-breccia; and thin bands of basal frictionite are indispensable clues for identifying deposits from giant rockslides that may remain morphologically inconspicuous otherwise. These sedimentary assemblages are diagnostic tools for distinguishing large rockslide debris from macro- and microscopically similar glacial deposits, tectonic fault-zone breccias, and impact breccias, and thus help avoid palaeoclimatic and tectonic misinterpretations, let alone misestimates of the hazard from giant rockslides. Moreover, experimental results from Mössbauer spectroscopy of frictionite samples support visual interpretations of thin sections, and demonstrate that short-lived (<10 s) friction-induced partial melting at temperatures >1500 °C in the absence of water occurred at the base of several giant moving rockslides. This finding supports previous theories of dry excess runout accompanied by comminution of rock masses down to μm-scale, and indicates that catastrophic motion of large fragmenting rock masses does not require water as a potential lubricant. [Copyright &y& Elsevier]

Knowledge about the detailed processes linked to the existence of permafrost in rockslide fractures is sparse. Large parts of the Jettan rockslide are located right below the discontinuous permafrost limit in the arctic part of the alpine landscape of northern Norway. Combining four years of meteorological and rockslide deformation data with temperature measurements from different parts of open fractures, shallow bedrock boreholes and air, as well as daily snow cover observations, allows a detailed identification of the key processes involved. These field data are the basis for the development of a permafrost controlled rockslide model. Seasonally, the deformation has a very distinctive pattern with high deformation starting abruptly right after snowmelt in May, and lasting until snow isolation in winter. Then there is a gradual transition to medium deformation as the ground is cooled further for another 1–2months. Finally, the winter period, when maximum snow occurs in the fractures, is characterized by limited or almost no deformation. The primary controlling deformation process is meltwater percolation into fractures in summer with significant refreezing, ice formation and temperature increase in the lower part of the fractures from −1°C to 0°C. Sporadic permafrost exists below the discontinuous permafrost limit, and may extend into open fractures and sliding planes. Another primary process is the significant cold air accumulation in fractures in early winter, due to the Balch effect, which significantly cools the fracture and surrounding rock promoting permafrost development. Finally, the cold air effect is stopped by snow isolation once enough snow has accumulated in the fracture by late winter. The deformation itself is thought to be controlled by changing shear strength of the brecciated sliding planes due to either changing ice temperatures and/or variations in water infiltration to the unsaturated sliding zones. The overall system is very locally controlled driving itself, and the effect of a future climate change can thus be of minor importance. [ABSTRACT FROM AUTHOR]

We propose a long-term probabilistic multi-hazard assessment for El Misti Volcano, a composite cone located <20 km from Arequipa. The second largest Peruvian city is a rapidly expanding economic centre and is classified by UNESCO as World Heritage. We apply the Bayesian Event Tree code for Volcanic Hazard (BET_VH) to produce probabilistic hazard maps for the predominant volcanic phenomena that may affect c.900,000 people living around the volcano. The methodology accounts for the natural variability displayed by volcanoes in their eruptive behaviour, such as different types/sizes of eruptions and possible vent locations. For this purpose, we treat probabilistically several model runs for some of the main hazardous phenomena (lahars, pyroclastic density currents (PDCs), tephra fall and ballistic ejecta) and data from past eruptions at El Misti (tephra fall, PDCs and lahars) and at other volcanoes (PDCs). The hazard maps, although neglecting possible interactions among phenomena or cascade effects, have been produced with a homogeneous method and refer to a common time window of 1 year. The probability maps reveal that only the north and east suburbs of Arequipa are exposed to all volcanic threats except for ballistic ejecta, which are limited to the uninhabited but touristic summit cone. The probability for pyroclastic density currents reaching recently expanding urban areas and the city along ravines is around 0.05 %/year, similar to the probability obtained for roof-critical tephra loading during the rainy season. Lahars represent by far the most probable threat (around 10 %/year) because at least four radial drainage channels can convey them approximately 20 km away from the volcano across the entire city area in heavy rain episodes, even without eruption. The Río Chili Valley represents the major concern to city safety owing to the probable cascading effect of combined threats: PDCs and rockslides, dammed lake break-outs and subsequent lahars or floods. Although this study does not intend to replace the current El Misti hazard map, the quantitative results of this probabilistic multi-hazard assessment can be incorporated into a multi-risk analysis, to support decision makers in any future improvement of the current hazard evaluation, such as further land-use planning and possible emergency management. [ABSTRACT FROM AUTHOR]

We present a new approach for mapping open cracks and tension fractures within rock slope instabilities and rock cliffs, which resides in high-resolution ground-based and airborne infrared thermography (IRT). The method is restricted to cold seasons, and its utility is demonstrated through three examples from the Flysch Belt of the Outer West Carpathians (rockslides at Kopce Hill and Mt. Kněhyně) and from the Northern Calcareous Alps (deep-seated gravitational slope deformations in Gschliefgraben/Mt. Traunstein). The approach is based on a contrast between temperatures deep within the rock mass, which at a depth of few meters represent local mean annual values, and winter-time temperatures of the ground surface. In winter, warmer, buoyant air from depth rises to the ground surface through open cracks and joints, and the temperature contrast can be detected by IRT. Our test survey was conducted in the beginning of February 2012, in order to achieve the best contrast between temperatures around open tension cracks and the adjacent ground. For temperature sensing, we used a FLIR B360 thermal camera; for airborne surveys in the ambient air, temperatures at the time of our surveys ranged from approximately −19 to −7 °C. IRT results conclusively revealed the presence of open cracks, loosened rock zones, and pseudo-karst caves over a distance sometimes greater than 1 km. The IRT approach proved useful for rapidly assessing the distribution of open cracks and tension fractures, key information required for assessing rockfall and rockslide hazard. [ABSTRACT FROM AUTHOR]

An integrated methodology based on traditional field and remote surveys such as terrestrial laser scanning and terrestrial infrared thermography is proposed, with the aim of defining susceptibility scenarios connected to rock slopes affected by instability processes. The proposed methodology was applied to a rock slope threatening a coastal panoramic roadway located in western Elba Island (Livorno district, central Italy). The final aim of the methodology was to obtain an accurate three-dimensional rock mass characterization in order to detect the potentially more hazardous rock mass portions, calculate their volume, and collect all the required geomechanical and geometrical parameters to perform a detailed stability analysis. The proposed approach proved to be an effective tool in the field of engineering geology and emergency management, when it is often urgently necessary to minimize survey time when operating in dangerous environments and gather all the required information as fast as possible. [ABSTRACT FROM AUTHOR]

Hummocks are topographic features of large landslides and rockslide-debris avalanches common in volcanic settings. We use scaled analog models to study hummock formation and explore their importance in understanding landslide kinematics and dynamics. The models are designed to replicate large-scale volcanic collapses but are relevant also to non-volcanic settings. We characterize hummocks in terms of their evolution, spatial distribution, and internal structure from slide initiation to final arrest. Hummocks initially form by extensional faulting as a landslide begins to move. During motion, individual large blocks develop and spread, creating an initial distribution, with small hummocks at the landslide front and larger ones at the back. As the mass spreads, hummocks can get wider but may decrease in height, break up, or merge to form bigger and long anticlinal hummocks when confined. Hummock size depends on their position in the initial mass, modified by subsequent breakup or coalescence. A hummock has normal faults that flatten into low-angle detachments and merge with a basal shear zone. In areas of transverse movement within a landslide, elongate hummocks develop between strike-slip flower structures. All the model structures are consistent with field observations and suggest a general brittle-slide emplacement for most landslide avalanches. Absence of hummocks and fault-like features in the deposit may imply a more fluidal flow of emplacement or very low cohesion of lithologies. Hummocks can be used as kinematic indicators to indicate landslide evolution and reconstruct initial failures and provide a framework with which to study emplacement dynamics. [ABSTRACT FROM AUTHOR]

Rock avalanches are the largest granular flows on Earth. In contrast to artificial, small-scale granular avalanches, they exhibit a large degree of fragmentation with reduction of average grain volume by a factor of up to 10-10. Even though fragmentation likely affects the whole dynamics of the rock avalanche, as yet the basic mechanics of the process is poorly known. In this work, a simple model is presented for the fragmentation of rock avalanches, assuming that most of the fragmentation occurs along force chains in the granular medium. The landslide motion is simulated along a curved bumpy profile path. The predicted grain spectra are found to agree reasonably with field data. [ABSTRACT FROM AUTHOR]

Abstract: The Pisciotta landslide is a slow-moving deep-seated rock slide in the Campania region of southern Italy, which has damaged a provincial road several times in the last decades and currently poses a hazard to the national railway that intersects the toe of the landslide. The landslide involves an Oligocene turbidite series, which is composed of intercalated calcarenites, marls and mudrocks. The principal objectives of this study were to investigate the morphological evolution of the unstable slope, quantitatively analyse ground deformations and construct an engineering-geological model that is consistent with the spatial features of the landslide. The long-term evolution of the unstable slope was assessed through the examination of available aerial photos from 1943 to 2006. Kinematic analyses of the ground deformations were conducted based on observed progressive displacement of the road, as evident from the topographic maps and orthophotos (1955–2006), and the bi-weekly displacement survey of 50 targets distributed across the landslide area (September 2006–March 2009). The engineering-geological model of the landslide was reconstructed from the stratigraphic data obtained from the study of borehole data and monitoring of inclinometers as well as from geological, structural and geophysical surveys. The analysis of the aerial photographs revealed an early stage of deformation in 1943, which has been gradually widening since then. In addition to the main scarp and the landslide flanks, other significant landslide structures such as the longitudinal and transverse cracks as well as the positive or negative morphologies were monitored and mapped in the subsequent years. These studies indicated a progressive erosion of the upper part of the slope and a bulging of the foot. Long-term kinematic analysis based on the progressive displacements of the road allowed the measurement of the ground deformations from 1955 to 2009, which revealed a cumulative horizontal displacement of up to 53m and an average velocity of 0.98myear−1, which has increased in the recent decades. In addition, the recent monitoring of the ground deformations demonstrated a continuous activity with an approximately constant rate of displacement and a composite kinematic history of the landslide body through differential displacements and associated velocities. The engineering-geological model of the landslide was found to be controlled by specific stratigraphic and structural constraints. The landslide involves a stratigraphic interval of the Saraceno Formation (Nord-Calabrese tectonic unit) with a largely marly–argillaceous composition whose structural setting displays complex folding (at the mesoscale) and faulting with an approximately monocline attitude of bedding and a downslope dip direction at the macroscale. The left flank of the landslide rests on a normal fault. [Copyright &y& Elsevier]

The slow movement of active deep-seated slope gravitational deformations (DSGSDs) and deep-seated rockslides can cause damage to structures and infrastructures. We use Permanent Scatterers Synthetic Aperture Radar Interferometry (PSInSAR™) displacement rate data for the analysis of DSGSD/rockslide activity and kinematics and for the analysis of damage to buildings. We surveyed the degree of damage to buildings directly in the field, and we tried to correlate it with the superficial displacement rate obtained by the PSInSAR™ technique at seven sites. Overall, we observe that the degree of damage increases with increasing displacement rate, but this trend shows a large dispersion that can be due to different causes, including: the uncertainty in the attribution of the degree of damage for buildings presenting wall coatings; the complexity of the deformation for large phenomena with different materials and subjected to differential behavior within the displaced mass; the absence of differential superficial movements in buildings, due to the large size of the investigated phenomena; and the different types of buildings and their position along the slope or relative to landslide portions. [ABSTRACT FROM AUTHOR]

The present paper illustrates the results of an integrated study of a large landslide located on the southern slope of Mount la Civita (Molise, Southern Apennine), an E-W elongated, SSE dipping and 890-m-high monocline carbonate ridge. The upper part of the slope affected by the landslide is largely controlled by strata attitude while its basal part is marked by a strike-slip fault causing the tectonic juxtaposition of the carbonate successions against predominantly clayey flysch units. An integrated study, including geological, geomorphological and geotechnical investigations, was carried out to determine the features of the landslide and to plan further investigation and monitoring. In particular, from 2002 to 2004, Differential Global Positioning System monitoring and core drillings, coupled with inclinometer measurements, were carried out to determine the landslide's kinematics, extent, depth to the surface of rupture and rates of movement. Inclinometer data revealed the presence of the rupture surface at a depth of about 20 m. DGPS monitoring allowed rates of movement up to several tens of centimetres per year to be recorded. The nearby village of Civitanova del Sannio can still be considered at risk due to the landslide, as recent remedial works, consisting mainly of very shallow re-shaping of the slope by blasting and partial filling of trenches, did not succeed in stopping its movement. [ABSTRACT FROM AUTHOR]

Highlights: [•] 3D numerical modeling of the wave generated by the Vajont rockslide. [•] Definition of the rocklide kinematics using a 3D approach. [•] Parallel 3D SPH numerical scheme obtained using the Compute Unified Device Architecture (CUDA) of nVidia devices. [•] Validation against data available in literature. [ABSTRACT FROM AUTHOR]

The Jiweishan landslide illustrates the failure pattern of an apparent dip slide of an oblique thick-bedded rockslide. Centrifugal modeling was performed using a model slope consisting of four sets of joints to investigate the landslide initiation mechanism. Crack strain gauges pasted between the slide blocks and the base failed in sequence from the rear to the front as the centrifugal acceleration increased. When the acceleration reached 16.3g, the instantaneous failure of the key block in the front triggered the apparent dip slide of all blocks. The physical modeling results and previous studies suggest that the strength reduction in the weak layer and the failure of the key block are the main reasons for the Jiweishan landslide. The centrifuge experiment validated the previously proposed driving-blocks-key-block model of apparent dip slide in oblique with inclined bedding rock slopes. In addition, the results from limit equilibrium method and centrifuge test suggest that even though the failure of the key block in the front is instantaneous, a progressive stable-unstable transition exists. [ABSTRACT FROM AUTHOR]

The activity of large rockslides is dependent on a combination of interplaying factors that control strain localization within the slope. In some cases, continued deformation may lead to widespread disaggregation of the slide mass (i.e., loss of cohesion and development of debris). Layers with markedly different composition and strength may eventually form, making it difficult to assess the actual nature of hazards and related risks posed to the valley bottom. This paper provides updated insights into the highly disaggregated and rapidly evolving Ruinon rockslide (Central Italian Alps) based on more than a decade of monitoring by means of a Ground-Based Interferometric Synthetic Aperture Radar (GBInSAR). The rockslide was recently affected by a prolonged period of exceptional surface velocities—consistently exceeding 1 m/day. Monitoring data are examined in order to estimate the thickness of the rapidly moving layer of upper chaotic debris by means of the balanced cross-section method as well as determine the effects of hydrological forcing on the slope displacements. Finite-element modelling is then used to derive hypotheses concerning the deformation behavior of the slide mass at greater depth and different elevations. It is suggested that the upper debris moves at rates several orders of magnitude higher than the underlying substrate, and that in relative terms the sensitivity to sliding of the two layers is similarly governed by the increase of piezometric levels in the spring/summer. On lower slopes, the activity of the upper debris appears to be also influenced by precipitation events that are not accompanied by a notable increase of the piezometric levels measured at the rear of the slide. Our findings show the importance of implementing long-term GBInSAR monitoring at challenging sites like Ruinon, where fieldwork and installation of instruments on the slide mass are not feasible. • Long-term GBInSAR monitoring of the highly disaggregated Ruinon rockslide. • An exceptional reactivation event caused surface velocities to exceed 1 m/day. • Thickness of the rapidly moving upper debris estimated from balanced cross-sections. • Accelerations related with seasonal rises of piezometric level. • Deformation behavior at depth and different elevations inferred from FEM modelling. [ABSTRACT FROM AUTHOR]

• Source parameters of rock burst in coal mine were obtained by Brune model. • Rupture scale and average slip on the rupture surface were calculated. • Slip distribution on the rupture surface of the seismic source was inversed. • Accuracy of seismic source parameters and slip distribution was verified. To assessment the source parameters and slip distribution on the rupture surface of a rock burst event in Qianqiu coal mine, and verify the accuracy of the source parameters and slip distribution on the rupture surface, four rock burst events in Qianqiu coal mine were selected for source analysis. Firstly, the source parameters of four rock burst events in Qianqiu coal mine were obtained based on the Brune model. Then, the rupture scale and average slip on the rupture surface of seismic source were identified by using the established relationship between rupture scale and moment magnitude. Finally, based on the k 2 rupture-slip model and the obtained source parameters, the slip distribution on the rupture surface was inverted to reveal the slip-rupture process of the source, and the accuracy of the seismic source parameters and the slip distribution on the rupture surface was verified based on the in-situ rupture-slip behavior. The results show that: the source parameters can be calculated using the Brune model and grid search method; the rupture scale and average slip on the rupture surface were obtained by establishing the relationship between the moment magnitude and the rupture scale of the source; based on the k2 rupture-slip model and the scale of rupture, the slip distribution on the rupture surface of a microseismic event in a coal mine can be deduced by inversion. The calculated source parameters and slip distribution of four rock burst events are consistent with the actual records of such events in a coal mine, which further verifies the accuracy of the source parameters and slip distribution of rock burst events. These results can be used to quantify and evaluate the rupture properties, scale and process of a rock burst, and provide reference for further study of the evolution process and risk assessment of rock burst events in coal mine. [ABSTRACT FROM AUTHOR]

The Guañacos fold and thrust belt, in the northern Neuquén Andes (37°-38°S; 70°30′-71°10′W), has been studied by many researchers focusing on the Quaternary tectonic activity, from a morphological to a structural perspective. Additionally, this portion of the Andes is quite peculiar due to the numerous geomorphic processes coeval with neotectonic, such as volcanic, mass-wasting, glacial, and fluvial processes. However, it is not yet clear the impact of each one of these processes on landscape evolution. This paper reviews the evidence for the geomorphological modeling of the Guañacos belt and analyses the effects of the various actuating processes over the drainage network, implementing different and novel morphometric indices. We studied the hypsometry of the main basins in the area and identified knickpoints of the trunk of each basin from the stream profile slope-area plot. Besides, we applied morphometric indices such as the k sn and the χ for all catchments to evaluate the state of equilibrium of the stream network and basin divides. Our results show disequilibrium conditions over the entire fluvial network consistent with rockslide deposits and active structures. This study also discusses the usefulness of the applied morphometric indices in an area with low neotectonic slip-rates, great mass-wasting deposits, and glacial erosion. Findings in this matter showed substantial differences in the indices' response whether the analyzed basin was primarily glacial or fluvial carved. Taken together, results in the Guañacos fold and thrust belt suggest that the glacial erosion and the subsequent rockslide deposits are the prime agents for landscape modeling, making it unable to acknowledge the effect of Quaternary tectonic activity. Only when they are absent is it possible to recognize the neotectonic signature over the drainage. • Landscape evolution in Southern Central Andes between 37° and 38° S was analyzed. • K sn and χ maps yield disequilibrium conditions in the stream network. • Slope-area plot reveal knickpoints and concavity more affected by rockslides deposits. • Glacial erosion and rockslide deposits obscure the neotectonic' effects over drainage. • Geomorphic and tectonic processes influence morphometric indices. [ABSTRACT FROM AUTHOR]

Practice-oriented finite element (FE) modelling strategies represent a fundamental tool for the seismic analysis and design of Cross Laminated Timber (CLT) structures. Although substantial research has been undertaken concerning the seismic behaviour of CLT buildings, practice-oriented FE modelling strategies are still at an early stage. This paper presents an upgrade of an existing practice-oriented FE design model for the seismic design of CLT structures. The upgrade is supported through the same modelling strategy presented by Christovasilis et al. (2020) adding some features of analytical equations models presented by Casagrande et al. (2016). 2D elements are used both for the modelling of CLT panels and for mechanical connections, which are represented by a horizontal strip with a height smaller than 7% of the height of the panel. Analytical equations for determining the elastic modulus of elasticity and the shear modulus of the horizontal strip are reported accounting for both rocking and sliding behaviour for single- and multi-panel CLT shearwalls, including the effect of the vertical loads by using a secant stiffness. The validation of the proposal is carried out in terms of the shearwall lateral stiffness through the results of experimental tests on full-scale shearwalls published by other authors and through a validation/comparison between a detailed non-linear model and the Christovasilis et al. (2020) strategy on two multi-storey seismic-resistant lateral systems configurations with different amount of vertical loads. Finally, a proposal for the initial layout of connections to reduce the iterative seismic design and analysis process for CLT buildings is presented through a case study. • Seismic practice-oriented FE models for CLT are discussed. • An upgrade of an existing practice-oriented FE seismic design model is proposed. • A modelling strategy that integrates the major deformation mechanisms is defined. • Validation and comparison via experimental and numerical approaches are performed. • A methodology for the initial layout for seismic design is presented. [ABSTRACT FROM AUTHOR]

Geohazards like landslides are widely spread in Ethiopia, especially in the steep and hilly areas of the highlands and Rift escarpments. One of the areas which are highly affected by landslides and associated problems is the Wabe Shebelle gorge in Southeastern Ethiopia. Such hazards have caused damage to roads, farmlands, and dwelling houses and othee engineering infrastructures. Therefore the purpose of this study was to evaluate the characteristics of landslides, define the major factors causing slope failures, and develop landslide susceptibility zonation which could be used for development planning. The research involved: (a) comprehensive field survey/inventory of failed or potentially unstable slopes, (b) evaluation of the geological and geotechnical properties of the soils and rocks, (c) assessment of the hydrogeological conditions of the area, (d) identifying the major factors controlling slope instability, and (e) landslide susceptibility zonation using the Analytical Hierarchy Process (AHP) and Frequency Ratio (FR) methods. The results of the study show that the major types of slope failures in the area include rockfalls, debris/earth slides, and rockslides. The main parameters influencing slope failures include slope angle, aspect, lithology, slope curvature, elevation, distance to road, distance to streams/rivers, and land use/cover. Results of the GIS-based landslide susceptibility mapping show that the most susceptible areas are those which are characterized by the following crucial conditions: (a) underlain by basalt and limestone formations, (b) slope gradients higher than 30°, and (c) with slope facing to east and northeast. A combination of both triggering, and conditional factors is believed to have contributed to the initiations of landslides, including road excavations and uncontrolled runoff. Based on the result, the following mitigations measures are recommended: (1) design of proper drainage structure on the roadside, (2) design of proper slope cuts along the road corridor and select planned dumping areas of road cut materials, (3) provision of retaining structures which resists the loads imposed by the slide material and integrated with sufficient drainage systems. In addition, it is advisable to promote bio-engineering as it could help to increase the stability of slopes and enhance the sustainability of roads and other infrastructures. • A combination of factors is contributed to the initiations of landslides, including road excavations and uncontrolled runoff. • Extreme destruction of roadside-like retain structures, ditches, and agricultural fields characterize the south-central and northern parts of the Wabe Shebelle Gorge, South Eastern Ethiopia. • From field observations, it has been found that most of the slope instability is induced due to the combination of several factors; therefore, an integrated approach of remedial measures may be helpful to minimize landslide hazards in the area. • The results of the study show that the major types of slope failures in the area include rockfalls, debris/earth slides, and rockslides. • Results of the GIS-based landslide susceptibility mapping show that the most susceptible areas are those which are characterized by the following: (a) underlain by basalt and limestone formations, (b) slope gradients higher than 30°, and (c) with slope facing to east and northeast. [ABSTRACT FROM AUTHOR]

Abstract: The primary aim of this research was to study the relationship between landslide motion and its causes, with reference to large, slow moving, reactivated translational rock slides. Surface displacements of the 22×106 m3 Utiku landslide, in central North Island, New Zealand were measured using continuous GPS (cGPS), for three years. The nature of the movement of such slides has often been difficult to determine because of poor temporal and spatial monitoring resolutions. After removal of tectonic plate motion, the temporal pattern of the landslide's surface motion could be understood to arise from irregular episodes of faster (up-to-21mm/day) and slower (up to 26mm/yr) post-failure landslide displacement, and seasonal cyclic displacements of about 20mm/yr–10mm per half year in alternating directions. Intervals of faster motion gave rise to displacements of between 10 and 120mm per event. Faster displacement was associated mostly with basal sliding (mechanism 1), involving deformation within a thin clay seam as recorded by borehole inclinometer surveys. Slower surface displacement involved permanent internal deformation of the larger landslide mass, consisting of plastic deformation within the landslide body and/or slip along existing internal planes of weakness, and slip on the slide base (mechanism 2); it accounted for up to 26mm/yr of displacement at a mean angle of about 49° from the horizontal, indicating that the slide mass was thinning as it moved down slope. Seasonal cyclic displacements were synchronous with changes in pore pressure, suggesting that it is a shrink/swell process (mechanism 3) associated with wetting and recharge of groundwater during the wetter winter months, leading to a downslope movement, and soil shrinkage leading to upslope rebounds during the dryer summer months. The brief periods of faster displacement were triggered by seasonal peaks in pore pressure, linked to long periods (12 to 20weeks) of increased precipitation and lowered evapotranspiration. Faster displacement, however, was not arrested by lowering pore pressure or by any other monitored factor. Similarly, periods of slower displacement did not correlate with pore pressure changes, or with any other monitored factor. This study has shown that the annual movement pattern of a reactivated landslide is a combination of these processes that generate a complex overall movement record. The field measurements showed real variability arising from variations in rainfall and pore pressure, which were overprinted with measurement noise that may mask some other processes. [Copyright &y& Elsevier]

Using hourly station rain gauge data in the warm season (May-October) during 1961-2006, the climatological features of the evolution of the rainfall process are analyzed by compositing rainfall events centered on the maximum hourly rainfall amount of each event. The results reveal that the rainfall process is asymmetric, which means rainfall events usually reach the maximum in a short period and then experience a relatively longer retreat to the end of the event. The effects of rainfall intensity, duration and peak time, as well as topography, are also considered. It is found that the asymmetry is more obvious in rainfall events with strong intensity and over areas with complex terrain, such as the eastern margin of the Tibetan Plateau, the Hengduan Mountains, and the Yungui Plateau. The asymmetry in short-duration rainfall is more obvious than that in long-duration rainfall, but the regional differences are weaker. The rainfall events that reach the maximum during 14:00-02:00 LST exhibit the strongest asymmetry and those during 08:00-14:00 LST show the weakest asymmetry. The rainfall intensity at the peak time stands out, which means that the rainfall intensity increases and decreases quickly both before and after the peak. These results can improve understanding of the rainfall process and provide metrics for the evaluation of climate models. Moreover, the strong asymmetry of the rainfall process should be highly noted when taking measures to defending against geological hazards, such as collapses, landslides and debris flows throughout southwestern China. [ABSTRACT FROM AUTHOR]

This work focuses on the characterization of seismic sources observed in clay–shale landslides. Two landslides are considered: Super-Sauze (France) and Valoria (Italy). The two landslides are developed in reworked clay–shales but differ in terms of dimensions and displacement rates. Thousands of seismic signals have been identified by a small seismic array in spite of the high-seismic attenuation of the material. Several detection methods are tested. A semi-automatic detection method is validated by the comparison with a manual detection. Seismic signals are classified in three groups based on the frequency content, the apparent velocity and the differentiation of P and S waves. It is supposed that the first group of seismic signals is associated to shearing or fracture events within the landslide bodies, while the second group may correspond to rockfalls or debris flows. A last group corresponds to external earthquakes. Seismic sources are located with an automatic beam-forming location method. Sources are clustered in several parts of the landslide in agreement with geomorphological observations. We found that the rate of rockfall and fracture events increases after periods of heavy rainfall or snowmelt. The rate of microseismicity and rockfall activity is also positively correlated with landslide displacement rates. External earthquakes did not influence the microseismic activity or the landslide movement, probably because the earthquake ground motion was too weak to trigger landslide events during the observation periods. [ABSTRACT FROM AUTHOR]

Many gently dipping translational rock slides have taken place in red Jurassic strata in Wanzhou which is located in the middle bank area of the Three Gorges Reservoir, China. In order to study the mechanism of these translational rock slides, conventional triaxial tests and creep tests on sandstone specimens from red Jurassic strata in Wanzhou are performed, and the rheological properties of the sandstone at accelerating creep stage are discussed. The quasi-static Nishihara model for transient and steady-state creep is modified by adding a strain-triggered inertial element in series, resulting in a phase of quadratic accelerating creep. The model fits the experimental data at all stages of creep, allowing its parameters to be inferred from the data. Finally, a sensitivity study for the analytical solution of the proposed model is carried out, showing the effects of the inertial element and stress level on the creep strain of sandstone. [ABSTRACT FROM AUTHOR]

Abstract: The studied Flysch sequence of Alicante occupies a widely populated area crossed by main communication routes. The slopes existing on this area usually suffer slope instabilities that cause substantial damage and a very high maintenance cost. In order to assess the type of instability mechanisms affecting these heterogeneous carbonatic slopes, in this paper a wide inventory of 194 Flysch rock slopes has been performed, reporting the existing lithologies, their competence and their relative arrangement and the geometrical relationship between bedding and the slope and the associated instability mechanism. All these data have been jointly used for performing an instability mechanisms characterization. For systematically characterizing the wide type of complex rock exposures existing in the study area, they are divided into basic units referred as lithological pattern columns to which the different observed instability mechanisms are associated. Inventoried instability mechanisms are diverse and sometimes are combined with each other. Rockfalls are a very common instability mechanism associated to the differential weathering and sapping of the marly lithologies which are present in a wide number of geometrical combinations. The other instability mechanisms closely depend on the combination of the geometrical and lithological parameters. Therefore, this work provides a new basic tool which can be easily used during preliminary project stages for knowing the instability mechanisms which can affect rock slopes excavated on carbonatic Flysch heterogeneous geological formations. [Copyright &y& Elsevier]

Abstract: The internal structure of landslide dams plays a key role in their stability; however, it has not been much studied, probably due to the difficulty in obtaining information on internal structure in most cases. Here, we examined the shear-wave-velocity structure of a rockslide dam by a surface-wave technique called multichannel analysis of surface waves (MASW). During the 2008 Wenchuan earthquake (Mw7.9), more than 60,000 landslides were triggered and 800 landslide dams formed. Those dams with a high risk of collapse threatened rescue activities, and almost all of the large landslide dams were treated by digging a sluiceway immediately after the earthquake. Although the risk of collapse of many landslide dams was removed or lowered, not all of the countermeasures were based on well controlled methods. To analyze the internal of landslide dams to assist in carrying out reliable countermeasures, we made detailed investigations on some of the dams, and here describe one landslide dam that occurred in the Tianchi area. Grain-size analysis revealed that the displaced landslide materials experienced fragmentation and segregation during the long movement. The shear-wave-velocity profile of the dam revealed that the dam consisted of three facies (carapace, body and basal facies). The boundary between facies is distinct. The body facies had a greater shear-wave velocity (compared to those landside dams that had suffered collapse failure during the construction of a sluiceway), showing that the dam consisted of more densely deposited materials. This kind of dam body had a lower permeability, capable of retarding seepage that triggers collapse failure of the dam body due to piping. Big blocks on the surface also enabled the dam body to have greater resistance to overflow and thus reducing possible collapse failure in the immediate aftermath of overtopping. [Copyright &y& Elsevier]

Abstract: Many formerly-glaciated mountains exhibit a high density of postglacial rock-slope failures (RSFs) in the form of rockslides, rock avalanches or deep-seated gravitational slope deformations. Such RSFs are often termed ‘paraglacial’ as they reflect pre-conditioning by glaciation and deglaciation. The temporal pattern of paraglacial RSFs is unknown. We employ 47 cosmogenic isotope exposure ages obtained for 17 catastrophic RSFs in the Scottish Highlands to test models of changes in RSF frequency since deglaciation. Our results show that RSF activity spans almost the entire postglacial period from ~17ka until ~1.5ka, and that the periodicity of sampled postglacial RSFs is statistically indistinguishable from a pattern of uniform periodicity (~1ka−1). Our data do not conform to proposed models of declining RSF frequency with time elapsed since deglaciation, but suggest that the temporal distribution of postglacial RSFs is best described by a combination of rapid response (enhanced RSF frequency during or immediately after deglaciation) followed by approximately constant periodicity. Our findings are consistent with near-surface fracturing of rock when glacially-induced confining stresses are removed, causing some failures during or immediately after deglaciation and reducing other slopes to critical conditional stability so that failure is triggered by progressive rock-mass weakening or by transient triggering mechanisms. Neither permafrost degradation (thaw of ice in joints) nor seismic activity offers a general explanation for triggering Scottish RSFs, but could be contributory in some cases. The quasi-constant periodicity inferred for Holocene RSFs implies that the probability of RSFs in this seismically-quiescent intraplate area has not changed in the past ~10ka, and that further (though infrequent) catastrophic RSFs are likely to occur in the future. [Copyright &y& Elsevier]

Abstract: Around 11.5∗106 m3 of rock detached from the eastern slope of the Santa Cruz valley (San Juan province, Argentina) in the first fortnight of January 2005. The rockslide–debris avalanche blocked the course, resulting in the development of a lake with maximum length of around 3.5km. The increase in the inflow rate from 47,000–74,000m3/d between April and October to 304,000m3/d between late October and the first fortnight of November, accelerated the growing rate of the lake. On 12 November 2005 the dam failed, releasing 24.6∗106 m3 of water. The resulting outburst flood caused damages mainly on infrastructure, and affected the facilities of a hydropower dam which was under construction 250km downstream from the source area. In this work we describe causes and consequences of the natural dam formation and failure, and we dynamically model the 2005 rockslide–debris avalanche with DAN3D. Additionally, as a volume ~24∗106 m3of rocks still remain unstable in the slope, we use the results of the back analysis to forecast the formation of a future natural dam. We analyzed two potential scenarios: a partial slope failure of 6.5∗106 m3 and a worst case where all the unstable volume remaining in the slope fails. The spreading of those potential events shows that a new blockage of the Santa Cruz River is likely to occur. According to their modeled morphometry and the contributing watershed upstream the blockage area, as the one of 2005, the dams would also be unstable. This study shows the importance of back and forward analysis that can be carried out to obtain critical information for land use planning, hazards mitigation, and emergency management. [Copyright &y& Elsevier]

Absolute dating of mass movements is crucial for disentangling possible release factors and determining the frequency of events. Here, we present an overview of a recent approach to dendrochronological dating of rockfalls, flows, landslides and avalanches. The results, based on 69 casestudies, show that methodological approaches to sampling and material processing differ considerably for different types of mass movements. Landslides are usually detected through abrupt growth changes and changes in stem eccentricity, whereas high-energy events as avalanches and flows are mostly identified by the formation of traumatic resin ducts, reaction wood, growth injuries and eccentricity changes. Cross-dating of dead wood is applicable as well. The dating of most mass movements except landslides is common, even with sub-annual resolution. In comparison to other methods of absolute dating, the main benefit of dendrochronology still lies in the high temporal resolution of the results. If living material is accessible, on-going research progress makes absolute dating of most mass-wasting events possible with sub-annual precision. [ABSTRACT FROM AUTHOR]

Abstract: Rockfall protection embankments are elevated massive structures designed to stop falling rock blocks. This paper discusses two specific facets of their design: their ability to control a block''s trajectory and to withstand the impact. Based on a critical review of the literature and the state of the art, this article treats the main features in the design of rockfall protection embankments and highlights the limitations of the methods used today. Rockfall simulation codes lack of precision as they are generally not calibrated nor validated on the block''s flying heights and velocities. And, analytical methods used to assess the response of embankments to impact globally fail in satisfactorily considering all the mechanisms involved and estimating their magnitude. These points should be considered by design engineers and could potentially lead to future improvements in the design of rockfall protection embankments. [Copyright &y& Elsevier]

The Aresawa rockslide in the Japanese Alps encountered a deep, partial collapse during an early snow-melting period in May 2004, followed by further progressive movement of the headscarp area. This paper reconstructs the pre-failure topography of the Aresawa rockslide based on the analysis of aerial photographs taken in multiple periods, and analyzes the factors controlling the threshold for the 2004 collapse. At least seven months before the collapse, new tension cracks emerged about 25 m behind the headscarp as a result of downslope movement of an unstable rock slab 5-10 × 10 m in volume, accompanied by the development of a slip plane below a pre-existing shallow trough (sackung feature). The collapse finally occurred when progressive weakening of the rock mass was combined with water infiltration into the ground during rapid snow melting. [ABSTRACT FROM AUTHOR]

Abstract: Rockfall is a widespread and hazardous process in mountain environments, but data on past events are only rarely available. Growth-ring series from trees impacted by rockfall were successfully used in the past to overcome the lack of archival records. Dendrogeomorphic techniques have been demonstrated to allow very accurate dating and reconstruction of spatial and temporal rockfall activity, but the approach has been cited to be labor intensive and time consuming. In this study, we present a simplified method to quantify rockfall processes on forested slopes requiring less time and efforts. The approach is based on a counting of visible scars on the stem surface of Common beech (Fagus sylvatica L.). Data are presented from a site in the Inn valley (Austria), where rocks are frequently detached from an ~200-m-high, south-facing limestone cliff. We compare results obtained from (i) the “classical” analysis of growth disturbances in the tree-ring series of 33 Norway spruces (Picea abies (L.) Karst.) and (ii) data obtained with a scar count on the stem surface of 50 F. sylvatica trees. A total of 277 rockfall events since A.D. 1819 could be reconstructed from tree-ring records of P. abies, whereas 1140 scars were observed on the stem surface of F. sylvatica. Absolute numbers of rockfalls (and hence return intervals) vary significantly between the approaches, and the mean number of rockfalls observed on the stem surface of F. sylvatica exceeds that of P. abies by a factor of 2.7. On the other hand, both methods yield comparable data on the spatial distribution of relative rockfall activity. Differences may be explained by a great portion of masked scars in P. abies and the conservation of signs of impacts on the stem of F. sylvatica. Besides, data indicate that several scars on the bark of F. sylvatica may stem from the same impact and thus lead to an overestimation of rockfall activity. [Copyright &y& Elsevier]

Abstract: This study presents in situ experiments carried out at an open cut mine in New South Wales (Australia). The research intends to improve the current knowledge on drapery systems for rockfall hazard management in mining environments. Blocks were released from the top of two different sections of the highwall: with and without a rockfall drapery system installed on the highwall. The trajectories of the blocks were recorded by using synchronised stereo pairs of high speed cameras. Velocities were derived from the trajectories and used to gather rockfall motion parameters (restitution coefficients) and various energies. [Copyright &y& Elsevier]

Mining induced seismicity was anticipated at the Tasmania Mine (formerly the Beaconsfield Gold Mine) before the commencement of modern production in 1999. Consideration of available stress measurement data from throughout Tasmania, coupled with rock material property data gathered at the Tasmania Mine during project feasibility investigations, suggested that the onset of mining induced seismicity could be expected at depth around 700 m below surface. That proved to be the case, with mining induced seismicity regularly observed from 760 m and below from 2002. Before 2006, management of seismicity was strictly controlled through geotechnical investigation and application of geotechnical control of all mining activities. The local stress regime was measured, understood and modelled in 2003. A temporary seismic monitoring system was operational from April 2004 and it was replaced with a permanent array in mid 2005. In late 2005, mining methods at the narrow vein Tasmania Mine were typical of mining methods employed at similar operations the world over. A substantial difference was the degree to which external opinion was sought, innovative techniques and methods were implemented, and a peer review of the entire process was undertaken. It was not enough: a seismically induced rockfall on 25 April (Anzac Day) 2006 took the life of a colleague. That the entire world was appraised of the accident was of secondary importance. An extensive coronial investigation found that no corporation or individual erred in respect of the Anzac Day accident. The clear message from that finding was that generally acceptable techniques for the management of mining induced seismicity, while at the limit of extant engineering experience, were below the expectations of the wider community. Management of seismicity at the Tasmania Mine post Anzac Day is a multidisciplinary activity that involves the entire workforce at every turn. Extensive seismic monitoring, saturation level instrumentation, development of innovative mining (and in particular stoping) methods, detailed 'first principals' ground support and reinforcement designs, exclusion and re-entry protocols surrounding all stope blasts, and the continued professional peer review of all geotechnical aspects of the operation, are part and parcel of the continued operation of the Tasmania Mine. This paper describes the latest developments in that process. [ABSTRACT FROM AUTHOR]

Mining in the production area Block 19 in the LKAB Kiirunavaara Mine has resulted in extensive seismic activity and several serious rockfalls. This paper describes a modelling study aimed at quantifying the seismic potential for future mining of Block 19, considering several different mining sequences. A three-dimensional discontinuum model was used, in which geological structures were included explicitly to simulate the development of fault slip seismic events. Four different mining sequences were simulated: three of which involved leaving the whole, or part of, Block 19 as an unmined pillar. Mining was simulated from the current active mining level and for a production period of >20 years ahead in time. The results were evaluated in terms of stress influences on critical infrastructure in the footwall of Block 19 and, more importantly, the possible extent of fault slip seismic events due to mining (by calculating seismic moments). The results showed that leaving a pillar in Block 19 may be less desirable as higher seismic moments will develop in the final mining stages. However, continued mining without a pillar will also likely result in an increased seismic activity in Block 19, which needs to be addressed appropriately. Block 19 should be mined before the neighbouring production areas, but additional and more detailed numerical modelling may be needed to fine-tune the extraction sequence for each level mined. [ABSTRACT FROM AUTHOR]

This paper describes the application of the combined finite-discrete element method (FDEM) for the simulation of two different rock slides observed at the Alpetto Mine in Cesana Brianza (Italy). Previous numerical modeling conducted to study the stability conditions of the high rock cut are used as comparison for the results obtained. The paper presents how the FDEM simulation was performed and discusses the ability and limits of the currently available combined method to simulate rock slide problems for practical purposes. [ABSTRACT FROM AUTHOR]

The twin tube, 1,765 m long Hanekleiv road tunnel is located in Southeast Norway. Ten years after completion of the tunnel, a serious rock fall occurred in the southbound tube, approximately 1.1 km from the northern tunnel entrance, in a fault zone containing swelling clay. In addition to swelling, gravitational collapse due to the very low internal friction played an important role in the development of the instability. Numerical analysis has been carried out for the rock slide. Modelling based on the support actually applied indicated cracks during tunnel excavation as well as the tunnel collapse. Simulation showed that even reinforced shotcrete ribs or 25 cm thick concrete lining, based on the Q-system, may not be sufficient for the fault zone. [ABSTRACT FROM AUTHOR]

Abstract: The Crimean Mountains in Ukraine constitute a seismically active region that is abundant in various types of mass movement. The limestone escarpments that rise above the Black Sea coast in the vicinity of the town of Yalta are particularly subject to considerable rockfall, landslide and debris flow processes that often endanger infrastructure and human life. One of these very active slopes is the area of the ancient Taraktash rockslide, characterised by active block-type movements (lateral spreading, toppling, and incipient sliding), rockfalls, ongoing sliding activities and debris flows. The aims of this study were (i) to employ tree-ring analysis to reconstruct a record of slope instabilities (mainly block-type movements, rockfalls, landslides and debris flows) within the Taraktash slope deformation over a period of more than two centuries and (ii) to establish the degree of correlation between periods of enhanced slope activity and both historical earthquakes and climatic data. The temporal frequency of significant slope processes was addressed through a tree-ring analysis that took 738 increment cores from 255 Crimean pine trees Pinus nigra ssp. pallasiana. The tree-ring record reveals periods of increased activity of block-type movements, rockfalls and landslides during the major earthquakes in 1790, 1875, 1927 and 1986. Although the slope processes studied are predominantly driven by seismic activity, their intensity and duration are also dependent on climatic factors. This is especially true for landslides and debris flows, which occurred mainly in years characterised by high precipitation totals. [Copyright &y& Elsevier]