Development of multi-purposes procedures and service tools for GNSS data processing finalized to monitor a deep-seated earthslide in the Dolomites (Italy)

The Corvara landslide is an active, large-scale, deep-seated and slow moving earthslide of about 30 Mm3 located in the Dolomites (Italy). It is frequently damaging a national road and, occasionally, isolated buildings and recre- ational ski facilities. In this work we present the analysis performed on data acquired thank to the installation of 3 DualFrequency GPS in permanent acquisition installed in the accumulation, track and source zone of the active portion of the landslide. In particular two years (2014 and 2015) of data were processed with several approaches and goals: daily time series were produced through Precise Point Positioning and Differential Positioning using both scientific packages and automatic on line tool based on open source libraries, specifically developed in order to provide a prototypal service. The achievable results based on single frequency (L1) data processing were also investigated in order to pave the way to the deployment of lowcost GPS receiver for this kind of application. Moreover, daily and sub-daily phenomena were analyzed. Different strategies were investigated in order to de- scribe the kinematics on the basis of 0.2 Hz data collected by the 3 permanent receivers. For particular events also the variometric approach, through the recent advances of VADASE, was applied, to detect significant movements. Finally, tropospheric parameters were estimated over the whole period in order to give a contribution to the SAR interferometry techniques. Also for this specific purpose and application, the possibilities of single frequency use were assessed

Multi-Temporal X-Band Radar Interferometry Using Corner Reflectors: Application and Validation at the Corvara Landslide (Dolomites, Italy)

From the wide range of methods available to landslide researchers and practitioners for monitoring ground displacements, remote sensing techniques have increased in popularity. Radar interferometry methods with their ability to record movements in the order of millimeters have been more frequently applied in recent years. Multi-temporal interferometry can assist in monitoring landslides on the regional and slope scale and thereby assist in assessing related hazards and risks. Our study focuses on the Corvara landslides in the Italian Alps, a complex earthflow with spatially varying displacement patterns. We used radar imagery provided by the COSMO-SkyMed constellation and carried out a validation of the derived time-series data with differential GPS data. Movement rates were assessed using the Permanent Scatterers based Multi-Temporal Interferometry applied to 16 artificial Corner Reflectors installed on the source, track and accumulation zones of the landslide. The overall movement trends were well covered by Permanent Scatterers based Multi-Temporal Interferometry, however, fast acceleration phases and movements along the satellite track could not be assessed with adequate accuracy due to intrinsic limitations of the technique. Overall, despite the intrinsic limitations, Multi-Temporal Interferometry proved to be a promising method to monitor landslides characterized by a linear and relatively slow movement rates

Deciphering seasonal effects of triggering and preparatory precipitation for improved shallow landslide prediction using generalized additive mixed models

The increasing availability of long-term observational data can lead to the development of innovative modelling approaches to determine landslide triggering conditions at regional scale, opening new avenues for landslide prediction and early warning. This research blends the strengths of existing approaches with the capabilities of generalized additive mixed models (GAMMs) to develop an interpretable approach that identifies seasonally dynamic precipitation conditions for shallow landslides. The model builds upon a 21-year record of landslides in South Tyrol (Italy) and separates precipitation that induced landslides from precipitation that did not. The model accounts for effects acting at four temporal scales: short-term &ldquo;triggering&rdquo; precipitation, medium-term &ldquo;preparatory&rdquo; precipitation, seasonal effects and across-year data variability. It provides relative landslide probability scores that were used to establish seasonally dynamic thresholds with optimal performance in terms of hit and false alarm rates, as well as additional thresholds related to user-defined performance scores. The GAMM shows a high predictive performance and indicates that more precipitation is required to induce a landslide in summer than in winter/spring, which can presumably be attributed mainly to vegetation and temperature effects. The discussion illustrates why the quality of input data, study design and model transparency are crucial for landslide prediction using advanced data-driven techniques.</p

Age of the Mt. Ortles ice cores, the Tyrolean Iceman and glaciation of the highest summit of South Tyrol since the Northern Hemisphere Climatic Optimum

In 2011 four ice cores were extracted from the summit of Alto dell'Ortles (3859 m), the highest glacier of South Tyrol in the Italian Alps. This drilling site is located only 37 km southwest from where the Tyrolean Iceman, similar to 5.3 kyrs old, was discovered emerging from the ablating ice field of Tisenjoch (3210 m, near the Italian-Austrian border) in 1991. The excellent preservation of this mummy suggested that the Tyrolean Iceman was continuously embedded in prehistoric ice and that additional ancient ice was likely preserved elsewhere in South Tyrol. Dating of the ice cores from Alto dell'Ortles based on Pb-210, tritium, beta activity and C-14 determinations, combined with an empirical model (COPRA), provides evidence for a chronologically ordered ice stratigraphy from the modern glacier surface down to the bottom ice layers with an age of similar to 7 kyrs, which confirms the hypothesis. Our results indicate that the drilling site has continuously been glaciated on frozen bedrock since similar to 7 kyrs BP. Absence of older ice on the highest glacier of South Tyrol is consistent with the removal of basal ice from bedrock during the Northern Hemisphere Climatic Optimum (6-9 kyrs BP), the warmest interval in the European Alps during the Holocene. Borehole inclinometric measurements of the current glacier flow combined with surface ground penetration radar (GPR) measurements indicate that, due to the sustained atmospheric warming since the 1980s, an acceleration of the glacier Alto dell'Ortles flow has just recently begun. Given the stratigraphic-chronological continuity of the Mt. Ortles cores over millennia, it can be argued that this behaviour has been unprecedented at this location since the Northern Hemisphere Climatic Optimum

Inherited structures and slope evolution: the case of the left slope of the Ridnaun Valley.

The left slope of the Ridnaun Valley (Sterzing/Vipiteno, South Tyrol, Italy), set on the crystalline units of the Austoalpine Nappe of the alpine orogenic wedge, shows evidence of quaternary gravitational evolution which highly depends on the interaction between the slope trend and the brittle/ductile structural setting. The slope is carved within the paragneisses rocks of the Oetztal - Stubai Unit and the micaschists of the Schneeberg Unit. These two units are separated by a NNW gentle dipping tectonic contact (mylonites and cataclasites), which obliquely intersects the E\u2013W slope, and is well described by ultracataclasitic layers following the regional low angle north-dipping schistosity. Folds with sub-horizontal E\u2013trending axes induce the change in the dip direction of the regional schistosity from N dipping to SE dipping. NNE\u2013SSW and N\u2013S trending faults, having a mean 1m thick incoherent fault breccia, affect the entire slope. These, as well as the folds and the ultracataclastic layers, has significant consequences on rock mass mechanical properties and on mechanisms and timing of the gravitational phenomena that developed along the slope. The results obtained by field work and the analysis of the LiDAR-derived digital elevation model clearly revealed different gravitational movements. A fully evolved gravitational collapse, having the typical features of a Rock Avalanche (RA), characterizes the central part of the slope; whereas to the east and west of the RA, deep seated gravitational slope deformations still involve the slope. The RA, whose deposit covers an area of about 2.4 km2, had obstructed the valley, resulting in a rock avalanche \u2013 dammed lake. This has been breached and run out at an interval of time not yet defined. An ongoing gravitational deformation involves the uphill sections of the slope, next to the crown area. In addition, to the west and east of the RA, morphostructural features as double ridge, scarps \u2013 counterscarps, trenches are evident. PS and DS - SAR (Synthetic Aperture Radar) interferometry data (derived ERS, ENVISAT and RADARSAT scenes), generated by the Tele-Rilevamento-Europa (TRE) and provided to the EURAC-Institute for Applied Remote Sensing for the EU-FP7 Project \u2019SAFER\u2019, with the purpose of an integration of the Inventory of Landslide Phenomena in Italy (IFFI Project), testify an ongoing movement on both the DSGSDs bordering the RA, highlighting a most unstable area at the western sector. The heterogeneous behavior of the slope is most likely controlled by the interaction between the ductile and brittle structures: on one hand the folds coupled with the non\u2013parallelism between the tectonic contact trend and the slope, ease the DSGSD formation and evolution and act as releasing factor for the RA crown area. On the other hand, the recognized fault network act as the lateral release of the unstable areas, and play a major role as a predisposing factor for gravitational failures because of the increasing degree of damage approaching each principal fault