Marta Chiarle

A digital photogrammetric method for measuring horizontal surficial movements on the Slumgullion earthflow, Hinsdale County, Colorado

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.

A method to reveal climatic variables triggering slope failures at high elevation

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.

Climate variability and Alpine glaciers evolution in Northwestern Italy from the Little Ice Age to the 2010s

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.

A web-based, relational database for studying glaciers in the Italian Alps

Glaciers are among the best terrestrial indicators of climate change and thus glacier inventories have attracted a growing, worldwide interest in recent years. In Italy, the first official glacier inventory was completed in 1925 and 774 glacial bodies were identified. As the amount of data continues to increase, and new techniques become available, there is a growing demand for computer tools that can efficiently manage the collected data. The Research Institute for Geo-hydrological Protection of the National Research Council, in cooperation with the Departments of Computer Science and Earth Sciences of the University of Turin, created a database that provides a modern tool for storing, processing and sharing glaciological data. The database was developed according to the need of storing heterogeneous information, which can be retrieved through a set of web search queries. The databases architecture is server-side, and was designed by means of an open source software. The website interface, simple and intuitive, was intended to meet the needs of a distributed public: through this interface, any type of glaciological data can be managed, specific queries can be performed, and the results can be exported in a standard format. The use of a relational database to store and organize a large variety of information about Italian glaciers collected over the last hundred years constitutes a significant step forward in ensuring the safety and accessibility of such data. Moreover, the same benefits also apply to the enhanced operability for handling information in the future, including new and emerging types of data formats, such as geographic and multimedia files. Future developments include the integration of cartographic data, such as base maps, satellite images and vector data. The relational database described in this paper will be the heart of a new geographic system that will merge data, data attributes and maps, leading to a complete description of Italian glacial environments.

Monitoring Rock Wall Temperatures and Microseismic Activity for Slope Stability Investigation at J.A. Carrel Hut, Matterhorn

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 investigate 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 temperature decrease present higher concentration of microseismic activity. However, not every drop in temperature is associated to microseismic activity, and the identification of the processes generating microseismic events in occasion of rapid temperature 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.

High Elevation Rock Falls and Their Climatic Control: a Case Study in the Conca di Cervinia (NW Italian Alps)

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.

Slope Instabilities in High-Mountain Rock Walls. Recent Events on the Monte Rosa East Face (Macugnaga, NW Italy)

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.

Interactive, 3D Simulation of Natural Instability Processes for Civil Protection Purposes

A computer simulation of a debris flow in motion, a landslide in evolution and a snow avalanche is here presented that was realized in the context of a series of risk education activities developed within the European project RISKNAT. The pc simulation allows to view in 3D and in their natural context of occurrence the three types of mass movements mentioned above. The peculiarity of the simulation is that the user is able to directly interact with the processes with the help of a special joystick that allows to vary the main parameters governing the process and also its sight. It is possible, for example, to choose an aerial view, or to get a view closer to the ground to observe in more detail the phenomenon in its progress. The computer simulation is based on real data and intends to spread among the local population, primarily exposed to risks, instructional and educational bases by offering a virtual experience of some recurrent natural processes occurring in alpine valleys. In fact it allows the user to reach a greater awareness of these latter, learning about their aspect, their mode of propagation, their velocity and their interaction with the natural and urbanized landscape. The simulation is therefore a tool to support the communication activities devoted to explain to the general public the civil protection basics, with the belief that the direct involvement, albeit virtual, in a situation of danger can be an important stimulus to better understand the forces of nature and to assimilate the basic behaviors needed for self defense.

The Glaciers of the Valle d’Aosta and Piemonte Regions: Records of Present and Past Environmental and Climate Changes

Glaciated mountains of the Valle d’Aosta and Piemonte regions are described in relation to the geological, geomorphological and climatic settings of the Western Alps. A comprehensive view of the present-day Alpine regional cryosphere is offered, and links to regional and local examples of its evolution through the Quaternary are provided. Pleistocene moraine amphitheatres (Ivrea and Rivoli-Avigliana) of the piedmont area recall the development stages of Alpine glaciology. Major glaciers (Lys, Miage, Belvedere, Rutor and Sabbione) of the highest peaks of the Western Alps (Mt. Bianco, Mt. Rosa) are analysed for their specific scientific, environmental, cultural and economic importance. The distinctive dynamic nature of the glacial landscape is illustrated by examples of active glacial landforms and related slope instability, whose sensitivity to climate changes can increase hazards and risks.

A System for Assessing the Past, Present and Future of Glacial Resources

The cryosphere is especially sensitive to the fluctuations of climatic parameters, and specifically to ongoing global warming. Mountain glaciers, in particular, are good indicators of climatic trends, as they have response times to climate forcing which are intermediate between snow (which responds mainly to short-term climate forcing) and permafrost/ground ice, whose response is delayed in time and conditioned by a complex ensemble of factors. When studying glacier response to climate change, the main objectives are: (i) understand the terrestrial, local impacts of global climatic changes, (ii) develop scenarios of the future evolution of glaciated areas, according to the available global climatic projections. This two objectives have both scientific and applied merits. The latter are related to the importance of glaciers in the water cycle, in sediment fluxes, and as a source of natural hazards. The combination of historical and geomorphological information with numerical models of climate systems and glacier response to climate forcing is one of the most robust approaches to address the study of glacier evolution in response to climate fluctuations and change. In order to be promptly available for use, historical and geomorphological data (including climatic ones) need to be properly organized in information management systems, which guarantee the preservation and standardization of data, along with their easy processing and retrieval. The present contribution aims at illustrating the experience gained through the application of this multidisciplinary approach to glaciers of the western Italian Alps.