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Rockfalls are one of the most common instability processes in high mountains. They represent a relevant issue, both for the risks they represent for (infra) structures and frequentation, and for their potential role as terrestrial indicators of climate change. This study aims to contribute to the growing topic of the relationship between climate change and slope instability at the basin scale. The selected study area is the Bessanese glacial basin (Western Italian Alps) which, since 2016, has been specifically equipped, monitored and investigated for this purpose. In order to provide a broader context for the interpretation of the recent rockfall events and associated climate conditions, a cross-temporal and integrated approach has been adopted. For this purpose, geomorphological investigations (last 100 years), local climate (last 30 years) and near-surface rock/air temperatures analyses, have been carried out. First research outcomes show that rockfalls occurred in two different geomorphological positions: on rock slopes in permafrost condition, facing from NW to NE and/or along the glacier margins, on rock slopes uncovered by the ice in the last decades. Seasonal thaw of the active layer and/or glacier debutressing can be deemed responsible for slope failure preparation. With regard to timing, almost all dated rock falls occurred in summer. For the July events, initiation may have been caused by a combination of rapid snow melt and enhanced seasonal thaw of the active layer due to anomalous high temperatures, and rainfall. August events are, instead, associated with a significant positive temperature anomaly on the quarterly scale, and they can be ascribed to the rapid and/or in depth thaw of the permafrost active layer. According to our findings, we can expect that in the Bessanese glacierized basin, as in similar high mountain areas, climate change will cause an increase of slope instability in the future. To fasten knowledge deepening, we highlight the need for a growth of a network of high elevation experimental sites at the basin scale, and the definition of shared methodological and measurement standards, that would allow a more rapid and effective comparison of data.

In a context of cryosphere degradation caused by climate warming, rock temperature is one of the main driving factors of rockfalls that occur on high-elevation mountain slopes. In order to improve the knowledge of this critical relationship, it is necessary to increase measurement capability of rock temperature and its variability in different lithological and slope/aspect conditions, and also to increase local scale studies, increasing the quality and the comparability of the data. This paper shows an example of metrological characterization of sensors used for rock temperature measurement in mountain regions, by means of the measurement uncertainty. Under such approach, data and results from temperature measurements carried out in the Bessanese high-elevation experimental site (Western European Alps) are illustrated. The procedures for the calibration and field characterization of sensors allow to measure temperature in different locations, depths and lithotypes, within 0.10 °C of overall uncertainty. This work has highlighted that metrological traceability is fundamental to asses data quality and establish comparability among different measurements; that there are strong differences between air temperature and near-surface rock temperature; and that there are significant differences of rock temperature acquired in different aspect conditions. Finally, solar radiation, slope/aspect conditions and lithotype, seem to be the main driving factors of rock temperature.

Air temperature in the European Alps shows warming over recent decades at an average rate of 0.3 °C/10 years, thereby outpacing the global warming rate of 0.2 °C/10 years. The periglacial environment of the Alps is particularly important for several aspects (i.e. hydropower production, tourism, natural hazards, indicator of global warming). However, there is a lack of specific and updated studies relating to temperature change in this environment. In order to fill this gap, the recent temperature trends in the periglacial environment of the Alps were analyzed. Mean/maximum/minimum daily air temperatures recorded by 14 land-based meteorological stations were used, and the temperature indices for the period 1990–2019 were calculated. The periglacial environment of the Alps showed a warming rate of 0.4 °C/10 years, 0.6 °C/10 years and 0.8 °C/10 years for the mean/maximum/minimum temperatures, respectively. These warming rates are higher than that observed for the entire Alpine area. In 2050 many glaciers of the Alps below 3000 m altitude are expected to be extinct, and all the areas previously occupied by glaciers will become periglacial. In order to manage and adapt to these changes, more in-depth climate analyses are needed. This is necessary for all the mountainous areas of the world, which are undergoing similar changes.

Glaciated and recently (post-Little Ice Age) deglaciated areas are very dynamic environments, undergoing continuous changes, in particular as a consequence of climatic fluctuations and cryosphere changes. The intense geomorphic activity that takes place here conditions natural hazard, sediment transport and tourist fruition. A geo-morphological mapping with applicative purposes has to take into account the peculiarities and the dynamism of these specific areas. We here propose a methodological approach based on the interpretation of a multitemporal set of aerial photos (from 1983 to 2012), in a GIS environment, with application to the sectors modeled by Little Ice Age glaciers in the upper Orco Valley (NW Italy). The result is a geo-morphological map focused on the elements that are most relevant for application purposes, complemented by a map of the spatio-temporal distribution of the natural instability processes identified in the study area for the reference period, aimed to highlight the recent dynamism of the geomorphological elements in the map.

Rockfalls are common instabilities in alpine areas and can cause significant damage. Since high mountains have been affected by an increasing number of these phenomena in the last years, a possible correlation with permafrost degradation induced by climate change has been hypothesized. To investigate this topic, a monitoring system, made of 5 triaxial geophones and 1 thermometer, was installed in 2007 at the Carrel hut (3829 m a.s.l., Matterhorn, North-western Alps), in the frame of the Interreg IIIA Alcotra project n. 196 "Permadataroc". The preliminary data processing relates to the classification of recorded signals, the identification of the significant microseismic events and the analysis of their distribution in time and space. The first results indicated a possible correlation between clusters of events and temperature trend, and a concentration of events in specific sectors of the rock mass. Research is still in progress. The recording of data for a longer period is planned to fully understand seasonal trends and spatial distribution of microseismic activity, and possible relations with permafrost degradation. Nevertheless, the preliminary observations prove that the monitoring system can detect noises generated by rock slope deformation. Once fully developed, this technique could become a helpful tool for early warning and preliminary stability assessments.

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.

Recent climate changes are increasing the frequency of rock-slope instabilities in the Alpine region. The formation of cracks leading to rockfalls causes a release of energy propagating in form of elastic waves. These latter can be detected by a suitable transducer array together with the vibrations generated by the impact of rockfalls. Geophones are among the most effective monitoring devices to investi-gate both these phenomena. A monitoring system composed by geophones and thermometers was installed at the J.A. Carrel hut (3829 m a.s.l., Matterhorn, NW Alps) in the framework of the Interreg Alcotra projects PERMAdataROC and MASSA by CNR IRPI and ARPA with the financial and logistic support of the Valle d'Aosta Region. The correlation between temperature trends and microseismic events is presented: cold periods characterized by a rapid tempera-ture decrease present higher concentration of microseismic activity. However, not every drop in temperature is associated to microseismic activity, and the identifi-cation of the processes generating microseismic events in occasion of rapid tem-perature decrease is still uncertain. The objective of the ongoing research activity is to analyze in deep the statistical correlation between the number of microseismic records and the temperatures of air and rock in order to investigate the existence of recurrent patterns in the detected signals.

The air temperature in the Alps has increased at a rate more than twice the global average in the last century, and a significant increase in the number of slope failures has also been documented, in particular in glacial and periglacial areas. Thus, the relationship between climatological forcing and processes of instability at high elevation is worth analyzing. We provide a simple, statistically based method aimed at identifying a relationship between climate factors and the triggering of geohazards. Our main idea is to compare the meteorological conditions at the time when the instability occurred with the typical conditions in the same place. Carrying out a straightforward analysis based on the use of the empirical distribution function, we are able to determine whether any of the meteorological variables had nonstandard values in the lead-up to the slope failure event, and thus to identify the variables that are likely to have acted as triggering factors for the slope failure. The method has been tested on five events in the glacial and periglacial areas of the Piedmont Alps (Northwestern Italy) occurring between 1989 and 2008. Out of these five case studies, our research shows that four can be attributed to climatic anomalies (rise of temperature and/or heavy precipitation). The results of this study may contribute to developing knowledge about the relationships between climatic variables and slope failures at high elevations, providing interesting insights into the expected impact of ongoing global warming on geohazards.

High runout distances characterize landslides falling on glaciers because of (1) low friction offered by ice to sliding and (2) complex rock-ice interactions that take place during mass motion. Block-fall models (two (2D) and three dimensional (3D)) were tested on the 1936 Felik landslide (Mount Rosa Massif). Geotechnical parameters were assessed through a back-analysis aided by field surveys, aerial photo and historical data analysis. Outcomes are verified for two rock-ice avalanches which ran along the Brenva Glacier (Mount Blanc Massif) in 1920 and 1997. Empirical models show poor precision (75%). 3D numerical models are too complex but 2D ones gave results that pointed out that real runouts exceed predicted ones by 30%, possibly due to fluidization processes. Rock-ice avalanches require attention because they originate in areas likely destined to experience permafrost degradation and glacier retreat. Copyright © 2002 John Wiley & Sons, Ltd.

One of the impacts of climate warming in recent years is the evident increase of the number of rock fall occurrences at high elevations. With few exceptions, these events have small magnitudes and thus are rarely reported and documented, even less so in the past. Therefore it is difficult to use a statistical approach to analyze of the relationships between climate warming and rock slope instability. On the other hand, it is often difficult to carry out a time analysis of meteorological conditions responsible for rock fall triggering, considering that very few automatic weather stations (AWS) are located in the areas and in the altitudinal range that are affected by cryosphere degradation (i.e. above c.a. 3,000 m elevation in the Alps), and that climatic conditions in high elevation environments are spatially and temporally variable. The present study addresses the above-mentioned issues through analysis of a series of small rock falls that occurred in the last 10 years on the Matterhorn and surrounding rock slopes. A specific focus is temperature: we present a preliminary analysis of the spatial and seasonal variability of the vertical temperature gradient in the Conca di Cervinia, where the Matterhorn is located, to illustrate the uncertainty in estimates of the thermometric conditions at high elevation rock fall sites.

We study the response of a set of glaciers in the Western Italian Alps to climate variations using the minimal glacier modeling approach, first introduced by Oerlemans. The mathematical models are forced over the period 1959–2009, using temperature and precipitation recorded by a dense network of meteorological stations and we find a good match between the observed and modeled glacier length dynamics. Forcing the model with future projections from a state-of-the-art global climate model in the RCP 4.5 and RCP 8.5 scenarios, we obtain a first estimate for the "expiration date" of these glaciers.

In this work, we analyze climate variability and glacier evolution for a study area in the Northwestern Italian Alps from the Little Ice Age (LIA) to the 2010s. In this area, glacier retreat has been almost continuous since the end of the LIA, and many glaciers are now extinct. We compared glaciological and climatic data in order to evaluate the sensitivity of glaciers to temperature and precipitation trends. We found that temperatures show significant warming trends, while precipitation shows no clear signal. After the 1980s, the total number of positive trends in temperature increased, particularly minimum temperature. The latter does not seem to be the only cause of glacier shrinkage but rather on acceleration of an ongoing trend documented since the end of the LIA. In some rare cases, the effects of warming trends on glacier dynamics have been accentuated by a concomitant decrease in precipitation. We hope that this study will contribute to increase the knowledge of the relationships between climate variation and glacier evolution in the Greater Alpine Region.

In early month of November 2007, a 1.4 km debris flow initiated on a steep south-facing slope above Moose Lake in Mount Robson Provincial Park, British Columbia. Snow meltwater was likely concentrated along a shallow seasonally frozen rupture surface, generating high pore water pressure. The debris flow bifurcated into two concentrated gullies before distributing as a debris flood on a snow-covered fan. The debris flow crossed a twin pipeline corridor and came to rest in a ditch against a highway berm. There was no damage to infrastructure. In many ways, the landslide resembles skin flows described in permafrost zones.

The Monte Rosa east face (Macugnaga, Italian Alps) is one of the highest flanks in the Alps. Steep hanging glaciers and permafrost cover large parts of the wall. Since the end of the Little Ice Age (about 1850) the Monte Rosa east face is undergoing a progressive reduction of its ice cover; moreover new instability phenomena related to permafrost degradation and rapid deglaciation have been occurring since over a decade ago. The progressive destabilization of high-mountain faces is a consequence of many factors, such as topography, geological and structural conditions, intense freeze-thaw activity and oversteepened slopes from glacial erosion. Two major events, an ice avalanche occurred in August 2005 and a rock avalanche occurred in April 2007 are briefly described in this paper. In both cases, the accumulation area was located on the Belvedere Glacier at the foot of the Monte Rosa east face. A 3D dynamic model (DAN3D) was applied in order to back analyze the runout of the events, enabling the calibration of the input parameters for the assumed rheological models.

Debris flows from glacier forefields, triggered by heavy rain or glacial outbursts, or clamming of streams by ice avalanches, pose hazards in Alpine valleys (e.g. the south side of Mount Blanc). Glacier-related debris flows are, in part, a consequence of general glacier retreat and the corresponding exposure of large quantities of unconsolidated, unvegetated, and sometimes ice-cored glacial sediments. This paper documents glacier-related debris flows at 17 sites in the Italian, French, and Swiss Alps, with a focus on the Italian northwest sector. For each case data are provided which describe the glacier and the instability. Three types of events have been recognized, based on antecedent meteorological conditions. Type 1 (9 documented debris flows) is triggered by intense and prolonged rainfall, causing water saturation of sediments and consequent failure of large sediment volumes (up to 800000 m 3). Type 2 (2 debris flows) is triggered by short rainstorms which may destabilize the glacier drainage system, with debris flow volumes up to 100000 m(3). Type 3 (6 debris flows) occurs during dry weather by glacial lake outbursts or ground/buried ice melting, with debris flow volumes up to 150000 m(3). A data base of historic cases is needed in order to advance process understanding and modelling, and thus improve hazard assessment. (C) 2007 Published by Elsevier B.V.

Extraordinary development s are taking place at Ghiacciaio del Belvedere near Macugnaga, Valle Anzasca, in the Italian Alps. A surge-type  ow acceleration started in the lower parts of the Monte-Rosa east face, leading to strong crevassing and deformation of Ghiacciaio del Belvedere, with extreme bulging of its orographic right margin. High water pressure and accelerated movement lasted into winter 2001/2002: in places, the ice is now starting to override moraines from the Little Ice Age. In addition, but fairly independently , a most active detachment zone for rock falls and debris  ows has been developing for several years now in the east face of Monte Rosa. Besides the scienti Ž c interest in these separate phenomena, both events affect the growing hazard potentia l to the local infrastructure and must be considered seriously.

The Po Valley brines represent the base level of the Quaternary aquifer located in a thick clay-sands sedimentary sequence. Geochemistry indicates that these are marine waters, evaporated to the stage of gypsum precipitation and trapped at the bottom of the basin in the late Messinian. Most of the groundwater samples collected from different springs and wells in the plain result from a mixture of these Na–Cl brines and shallow groundwaters laterally recharged by the Alpine and Apennine chains. Natural outflows of brackish waters are associated with major tectonic features. Mud volcanoes, located in the eastern sector of the Po plain, are constantly monitored as sudden chemical changes are significant precursors of seismic activity. In the western sector, calcite-filled veins isotopically record different degrees of water-rock interaction. These are outcropping fossil conduits, where mixing between shallow groundwaters and deep seated brines has occurred. The temporal continuity of the hydrological circuits allows the reconstruction of past and present groundwater circulation patterns. This paper summarises and integrates the geochemical data produced over many years in order to obtain a regional picture of brine origins and the natural mechanisms of groundwater flow.

The traditional approach to making aerial photographic measurements uses analog or analytic photogrammetric equipment. We have developed a digital method for making measurements from aerial photographs which uses geographic information system (GIS) software, and primarily DOS-based personal computers. This method, which is based on the concept that a direct visual comparison can be made between images derived from two sets of aerial photographs taken at different times, was applied to the surface of the active portion of the Slumgullion earthflow in Colorado to determine horizontal displacement vectors from the movements of visually identifiable objects, such as trees and large rocks. Using this method, more of the slide surface can be mapped in a shorter period of time than using the standard photogrammetric approach. More than 800 horizontal displacement vectors were determined on the active earthflow surface using images produced by our digital photogrammetric technique and 1985 (1:12,000-scale) and 1990 (1:6,000-scale) aerial photographs. The resulting displacement field shows, with a 2-m measurement error (~10%), that the fastest moving portion of the landslide underwent 15-29 m of horizontal displacement between 1985 and 1990.