scholarly journals Climate anomalies associated with the occurrence of rockfalls at high-elevation in the Italian Alps

2016 ◽  
Vol 16 (9) ◽  
pp. 2085-2106 ◽  
Author(s):  
Roberta Paranunzio ◽  
Francesco Laio ◽  
Marta Chiarle ◽  
Guido Nigrelli ◽  
Fausto Guzzetti
Keyword(s):  
Slope Failure ◽  
Eastern Alps ◽  
High Elevation ◽  
Slope Instability ◽  
Slope Failures ◽  
Italian Alps ◽  
Regional Patterns ◽  
Climate Anomalies ◽  
Climate Parameters ◽  
Permafrost Thaw

Abstract. Climate change is seriously affecting the cryosphere in terms, for example, of permafrost thaw, alteration of rain ∕ snow ratio, and glacier shrinkage. There is concern about the increasing number of rockfalls at high elevation in the last decades. Nevertheless, the exact role of climate parameters in slope instability at high elevation has not been fully explored yet. In this paper, we investigate 41 rockfalls listed in different sources (newspapers, technical reports, and CNR IRPI archive) in the elevation range 1500–4200 m a.s.l. in the Italian Alps between 1997 and 2013 in the absence of an evident trigger. We apply and improve an existing data-based statistical approach to detect the anomalies of climate parameters (temperature and precipitation) associated with rockfall occurrences. The identified climate anomalies have been related to the spatiotemporal distribution of the events. Rockfalls occurred in association with significant temperature anomalies in 83 % of our case studies. Temperature represents a key factor contributing to slope failure occurrence in different ways. As expected, warm temperatures accelerate snowmelt and permafrost thaw; however, surprisingly, negative anomalies are also often associated with slope failures. Interestingly, different regional patterns emerge from the data: higher-than-average temperatures are often associated with rockfalls in the Western Alps, while in the Eastern Alps slope failures are mainly associated with colder-than-average temperatures.

scholarly journals Climate anomalies associated to the occurrence of rockfalls at high-elevation in the Italian Alps

2016 ◽  
Author(s):  
Roberta Paranunzio ◽  
Francesco Laio ◽  
Marta Chiarle ◽  
Guido Nigrelli ◽  
Fausto Guzzetti
Keyword(s):  
Climate Change ◽  
Slope Failure ◽  
High Elevation ◽  
Slope Instability ◽  
Slope Failures ◽  
Italian Alps ◽  
Regional Patterns ◽  
Climate Anomalies ◽  
Permafrost Thaw ◽  
The Impact

Abstract. Climate change is seriously affecting the cryosphere, in terms, for example of permafrost thaw, alteration of rain/snow ratio, glacier shrinkage. There is concern about the increasing number of rockfalls at high elevation in the last decades. Nevertheless, the impact of climate variables on slope instability at high elevation has not been fully explored yet. In this paper, we investigate 41 rockfalls occurred at high elevation in the Italian Alps between 1997 and 2013 in the absence of an evident trigger. We apply and improve an existing data-based, statistical approach to detect the anomalies of climate parameters (temperature and precipitation) associated to rockfall occurrences. The identified climate anomalies have been related to the spatio-temporal distribution of the events. Rockfalls occurred in association with temperature anomalies in 83 % of our case studies. Temperature represents a key factor contributing to slope failure occurrence in different ways. As expected, warmer temperatures accelerate snowmelt and permafrost thaw; however, surprisingly, negative anomalies are also often associated to slope failures. Interestingly, different regional patterns emerge from the data: higher-than-average temperatures are often associated to rockfalls in the Western Alps, while in the Eastern Alps slope failures are mainly associated to colder-than-average temperatures. The results of this study represent a first step towards the identification of the possible role of climate change in the triggering of slope failures in a mountain environment.

Debris-cover on glaciers in the Austrian Alps. Regional patterns, Changes and Significance.

2021 ◽  
Author(s):  
Jan-Christoph Otto ◽  
Fabian Fleischer ◽  
Robert Junker ◽  
Daniel Hölbling
Keyword(s):  
Climate Warming ◽  
Regional Scale ◽  
Eastern Alps ◽  
High Elevation ◽  
Regional Variability ◽  
Mountain Areas ◽  
Regional Patterns ◽  
Austrian Alps ◽  
Glacier System ◽  
Debris Cover

<p>Debris cover on glaciers is an important component of glacial systems as it influences climate-glacier dynamics and thus the lifespan of glaciers. Increasing air temperatures, permafrost thaw, as well as rock faces freshly exposed by glacier downwasting results in increased rockfall activity and debris input into the glacier system. In the ablation zone, negative mass balances result in an enhanced melt-out of englacial debris to the glacier system. Glacier debris cover thus represents a signal of climate warming in mountain areas. To assess the temporal development of debris on glaciers of the Eastern Alps, Austria, we mapped debris cover on 255 of the more than 800 glaciers using Landsat data at three time steps between 1996 and 2015. We applied a ratio-based threshold classification technique using existing glacier outlines. The debris cover evolution was subsequently compared to glacier changes. Glacier and glacier catchment characteristics have been analysed using GIS techniques and statistics in order to investigate potential reasons for debris cover change.</p><p>Across the Austrian Alps debris cover increased by more than 10% between 1996 and 2015 while glaciers retreated significantly in response to climate warming. Debris cover distribution shows regional variability with some mountain ranges being characterised by mean debris cover on glaciers of up to 75%. We also observed a general rise of mean elevation of debris cover on glaciers in Austria. Debris cover distribution and dynamics are highly variable due to topographic, lithological and structural settings that determine the amount of debris delivered to and stored in the glacier system. Lower relative debris cover is observed on glaciers with higher mean and maximum elevation. Additionally, glaciers with increased mean slope, as well as catchments with large areas of steep slopes and a high elevation range of these slopes tend to show higher debris cover. Both parameters indicate that the influence of the steep rockwalls in the glacier catchment is a first order control on debris cover at regional scale. We can also show that catchments with a high percentage of potential permafrost distribution contain glaciers with a higher relative debris cover.</p><p>Despite strong variation in debris cover, all glaciers investigated melted at increasing rates. We conclude that the retarding effects of debris cover on the mass balance and melt rate of Austrian glaciers is strongly subdued compared to other mountain areas. The study indicates that if this trend continues many glaciers in Austria may become fully debris covered in the future. However, since debris cover seems to have little impact on melt rates in the study area it will therefore not lead to a prolonged existence of debris-covered ice compared to clean ice glaciers.</p>

Observations on Holocene subfossil tree remains from high-elevation sites in the Italian Alps

The Holocene ◽  
2018 ◽  
Vol 28 (12) ◽  
pp. 2017-2027 ◽  
Author(s):  
Mauro Bernabei ◽  
Jarno Bontadi ◽  
Kurt Nicolussi
Keyword(s):  
Tree Ring ◽  
Radiocarbon Dating ◽  
Climatic Variability ◽  
Eastern Alps ◽  
High Elevation ◽  
Anthropogenic Factors ◽  
Italian Alps ◽  
Sample Distribution ◽  
Groundwater Levels ◽  
Growth Decline

Subfossil tree remains from 38 high-elevation sites in the eastern Alps, which were mostly located in the province of Trentino, Italy, were dendrochronologically analysed. A total of 909 samples were collected, 497 of which were dated to calendar years through dendrochronology and separated into six groups. A further tree-ring series of 20 samples were cross-dated into two groups and their ages established by means of radiocarbon dating. The new Trentino Chronology that was established on the basis of these samples covers more than 80% of the last ca. 11,500 years. The uneven distribution of wood samples through time is most likely caused by different factors, for example, climatic and anthropogenic factors. According to our observations, the trees fell at the sites where they were found. The tree-ring series show that trees often died after a period of pronounced growth decline, for example, as a consequence of variations in groundwater levels. A comparison of the Holocene sample distribution of the new Trentino Chronology with contemporaneous records of other European tree-ring chronologies suggests that, at least partly, the greater scale of climatic variability influenced the depositional frequency. The new data contribute to our understanding of past climatic variability and environmental dynamics.

scholarly journals Slope Failure in a Period of Increased Landslide Activity: Sennwald Rock Avalanche, Switzerland

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 331
Author(s):  
Selçuk Aksay ◽  
Susan Ivy-Ochs ◽  
Kristina Hippe ◽  
Lorenz Grämiger ◽  
Christof Vockenhuber
Keyword(s):  
Slope Failure ◽  
Rock Avalanche ◽  
Eastern Alps ◽  
Rock Failure ◽  
Rhine River ◽  
Stratigraphic Sequence ◽  
Exposure Age ◽  
Wet Climate ◽  
Cosmogenic Nuclide Dating ◽  
Additional Support

The Säntis nappe is a complex fold-and-thrust structure in eastern Switzerland, consisting of numerous tectonic discontinuities and a range of hillslopes prone to landsliding and large slope failures that modify the topography irreversibly. A slope failure, namely the Sennwald rock avalanche, occurred in the southeast wall of this fold-and-thrust structure due to the rock failure of Lower Cretaceous Helvetic limestones along the Rhine River valley. In this research, this palaeolandslide is examined in a multidisciplinary approach for the first time with detection and mapping of avalanche deposits, dynamic run-out modelling and cosmogenic nuclide dating. During the rock failure, the avalanche deposits were transported down the hillslope in a spreading-deck fashion, roughly preserving the original stratigraphic sequence. The distribution of landslide deposits and surface exposure age of the rock failure support the hypothesis that the landslide was a single catastrophic event. The 36Cl surface exposure age of avalanche deposits indicates an age of 4.3 ± 0.5 ka. This time coincides with a notably wet climate period, noted as a conditioning factor for landslides across the Alps in the mid-Holocene. The contemporaneity of our event at its location in the Eastern Alps provide additional support for the contention of increased regional seismic activity in mid-Holocene.

scholarly journals The evolution of slope failures: mechanisms of rupture propagation

2004 ◽  
Vol 4 (1) ◽  
pp. 147-152 ◽  
Author(s):  
D. N. Petley
Keyword(s):  
Slope Failure ◽  
Complex Stress ◽  
Basal Region ◽  
Rupture Propagation ◽  
Slope Failures ◽  
Stress Regime ◽  
Detailed Surface ◽  
Landslide Mass ◽  
Region Data ◽  
Detailed Assessment

Abstract. Forecasting the occurrence of large, catastrophic slope failures remains very problematic. It is clear that in order advance this field a greater understanding is needed of the processes through which failure occurs. In particular, there is a need to comprehend the processes through which a rupture develops and propagates through the slope, and the nature of the inter-relationship between the stress and strain states of the landslide mass. To this end, a detailed analysis has been undertaken of the movement records for the Selborme Cutting slope failure, in which failure was deliberately triggered through pore pressure elevation. The data demonstrate that it is possible to determine the processes occurring in the basal region of the landslide, and thus controlling the movement of the mass, from the surface movement patterns. In particular, it is clear that the process of rupture development and propagation has a unique signature, allowing the development of the rupture to be traced from detailed surface monitoring. For landslides undergoing first time failure through rupture propagation, this allows the prediction of the time of failure as per the "Saito" approach. It is shown that for such predictions to be reliable, data from a number of points across the landslide mass are needed. Interestingly, due to the complex stress regime in that region, data from the crown may not be appropriate for failure prediction. Based upon these results, the application of new techniques for the detailed assessment of spatial patterns of the development of strain may potentially allow a new insight into the development of rupture surfaces and may ultimately permit forecasting of the temporal occurrence of failure.

Recurrent rock avalanches progressively dismantle mountain ridges in the Longmen Shan, China, most recently in the 2008 Wenchuan earthquake

2021 ◽  
Author(s):  
Janusz Wasowski ◽  
Maurice McSaveney ◽  
Luca Pisanu ◽  
Vincenzo Del Gaudio ◽  
Yan Li ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Ambient Noise ◽  
Slope Failure ◽  
Mass Movement ◽  
Rock Avalanche ◽  
Ground Vibration ◽  
Source Area ◽  
Slope Failures ◽  
Rock Avalanches ◽  
Beichuan County

<p>Large earthquake-triggered landslides, in particular rock avalanches, can have catastrophic consequences. However, the recognition of slopes prone to such failures remains difficult, because slope-specific seismic response depends on many factors including local topography, landforms, structure and internal geology. We address these issues by exploring the case of a rock avalanche of >3 million m<sup>3</sup> triggered by the 2008 Mw7.9 Wenchuan earthquake in the Longmen Shan range, China. The failure, denominated Yangjia gully rock avalanche, occurred in Beichuan County (Sichuan Province), one of the areas that suffered the highest shaking intensity and death toll caused by co-seismic landsliding. Even though the Wenchuan earthquake produced tens of large (volume >1 million m<sup>3</sup>) rock avalanches, few studies so far have examined the pre-2008 history of the failed slope or reported on the stratigraphic record of mass-movement deposits exposed along local river courses. The presented case of the Yangjia gully rock avalanche shows the importance of such attempts as they provide information on the recurrence of large slope failures and their associated hazards. Our effort stems from recognition, on 2005 satellite imagery, of topography and morphology indicative of a large, apparently pre-historic slope failure and the associated breached landslide dam, both features closely resembling the forms generated in the catastrophic 2008 earthquake. The follow-up reconstruction recognizes an earlier landslide deposit exhumed from beneath the 2008 Yangjia gully rock avalanche by fluvial erosion since May 2008. We infer a seismic trigger also for the pre-2008 rock avalanche based on the following circumstantial evidence: i) the same source area (valley-facing, terminal portion of a flat-topped, elongated mountain ridge) located within one and a half kilometer of the seismically active Beichuan fault; ii) significant directional amplification of ground vibration, sub-parallel to the failed slope direction, detected via ambient noise measurements on the ridge adjacent to the source area of the 2008 rock avalanche and iii) common depositional and textural features of the two landslide deposits. Then, we show how, through consideration of the broader geomorphic and seismo-tectonic contexts, one can gain insight into the spatial and temporal recurrence of catastrophic slope failures  in Beichuan County and elsewhere in the Longmen Shan. This insight, combined with local-scale geologic and geomorphologic knowledge, may guide selection of suspect slopes for reconnaissance, wide-area ambient noise investigation aimed at discriminating their relative susceptibility to co-seismic catastrophic failures. We indicate the feasibility of such investigations through the example of this study, which uses 3-component velocimeters designed to register low amplitude ground vibration.</p>

scholarly journals Variability of Cloudiness over Mountain Terrain in the Western United States

2017 ◽  
Vol 18 (5) ◽  
pp. 1227-1245 ◽  
Author(s):  
Edwin Sumargo ◽  
Daniel R. Cayan
Keyword(s):  
United States ◽  
Large Scale ◽  
Spatial Scales ◽  
High Elevation ◽  
Empirical Orthogonal Functions ◽  
Western United States ◽  
Spatial And Temporal Variability ◽  
Regional Patterns ◽  
Cloud Albedo

Abstract This study investigates the spatial and temporal variability of cloudiness across mountain zones in the western United States. Daily average cloud albedo is derived from a 19-yr series (1996–2014) of half-hourly Geostationary Operational Environmental Satellite (GOES) images. During springtime when incident radiation is active in driving snowmelt–runoff processes, the magnitude of daily cloud variations can exceed 50% of long-term averages. Even when aggregated over 3-month periods, cloud albedo varies by ±10% of long-term averages in many locations. Rotated empirical orthogonal functions (REOFs) of daily cloud albedo anomalies over high-elevation regions of the western conterminous United States identify distinct regional patterns, wherein the first five REOFs account for ~67% of the total variance. REOF1 is centered over Northern California and Oregon and is pronounced between November and March. REOF2 is centered over the interior northwest and is accentuated between March and July. Each of the REOF/rotated principal components (RPC) modes associates with anomalous large-scale atmospheric circulation patterns and one or more large-scale teleconnection indices (Arctic Oscillation, Niño-3.4, and Pacific–North American), which helps to explain why anomalous cloudiness patterns take on regional spatial scales and contain substantial variability over seasonal time scales.

scholarly journals Numerical Analysis of Soil Slope Stabilization by Soil Nailing Technique

2019 ◽  
Vol 9 (4) ◽  
pp. 4469-4473
Author(s):  
D. A. Mangnejo ◽  
S. J. Oad ◽  
S. A. Kalhoro ◽  
S. Ahmed ◽  
F. H. Laghari ◽  
...  
Keyword(s):  
Factor Of Safety ◽  
Slope Failure ◽  
Limit Equilibrium ◽  
Slope Instability ◽  
Soil Nailing ◽  
Soil Slope ◽  
Prevention Measures ◽  
Soil Nail ◽  
Soil Shear Strength ◽  
Nail Diameter

Slope instability may be a result of change in stress conditions, rise in groundwater table and rainfall. Similarly, many slopes that have been stable for several years can abruptly fail due to changes in geometry, weak soil shear strength or as the effect of an external force. Debris flows (i.e. slope failures) take place without any warning and can have devastating results. So, it is vital to understand the slope failure mechanism and adopt safety prevention measures. Soil nailing is one of the widely used stabilization techniques for soil slopes. In this study, soil nail technique is proposed to upgrade the existing slope in clay. A parametric study was conducted to understand the effects of different nail diameter (i.e. 25mm and 40mm) and nail inclination (i.e. 200, 250, 300, 350 and 400) on slope stability. Morgenstern-Price (i.e. limit equilibrium) method was used to determine the factor of safety of the slope. It was found that the factor of safety of the existing slope improved significantly with three rows of 40mm diameter nail at an inclination of 400.

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