R. Francese

Geophysical Imaging of the WWI Archeological Site of Linke Peak (Forni Glacier, Italian Central Alps)

The centenary of World War I triggered several and relevant studies in the fields of Conflict Archeology. The research scenario becomes even more challenging when the study site is located at high altitude in the Alps were past battles and also the modern research should face extreme conditions. A major research project was recently undertaken in the saddle between Mount Vioz and the Linke peak, in the Cevedale massif, where the progressive retreat of the Forni and of the Vedretta Rossa glaciers exposed barracks, tunnels, barbed wire, sledges, ammunitions and several other war remains. Geophysical imaging was the core of the project that was focused on a double objective: mapping possible WWI remains embedded in the ice and a obtaining some information on the glacier. Results from two different geophysical campaigns were encouraging as radar and seismic profiling provided detailed data about geometry and properties of the glacier as well as unexpected evidences of buried structures.

GPR and seismic surveying in the World War I scenario of Punta Linke (Ortles-Cevedale Group, Italian Alps).

The Ortles-Cevedale Group was the setting of repeated clashes occurring under extreme conditions and at the highest altitudes of all fightings in the Great War (WWI). The research scenario associated with the group is very challenging because modern research faces a series of logistical and climatic obstacles. The gradual retreat of glaciers has unearthed several archaeological remains of WWI such as barracks, barbed wire, military ammunition, weapons and other materials. The study site is the saddle between M. Vioz and Punta Linke, where the Historic War Museum of Pejo, under the direction of the Archaeological Service of the Province of Trento (Soprintendenza per i Beni Culturali, Ufficio Beni Archeologici), started an archaeological excavation in the year 2009 of some of the infrastructure of the cableway station, which also includes a tunnel section in the bedrock. The saddle is placed at the head of Forni Glacier. GPR and seismic imaging was the best survey choice to characterize the glaciological and geo-archaeological context and to find structures or remains within the ice mass. Geophysical imaging spanned two campaigns in the years 2010 and 2011. The ice-rock interface was reconstructed in detail to depths greater than 45-50 m. The surface of the bedrock reveals a complex morphology, with several undulations and two rocky ridges elongated in the NNW-SSE direction. They identified some anomalous reflectors within the ice mass located near the western edge of the saddle of Punta Linke. The interpretation of radar profiles seems to indicate the presence of a tunnel in the ice, whose geometry and position is similar to others excavated in alpine glaciers during the Great War.

High-resolution Seismic Imaging of the Pian di Neve Glacier on the Adamello Massif (Italy)

Active seismic investigations, generally employed to image the earth interior, are also widely applied in glaciology to map the thickness of glaciers and to study the basal sediment properties. In this work we present the results of a 1-km multichannel seismic survey carried out on the Pian di Neve, a high altitude glacier located in the Adamello massif (Italy), with the purpose to image the glacier bottom and obtain the ice thickness profile. The Pian di Neve occupies a 18-km² plateau at an altitude of between 3100 and 3400 m, and together with the adjacent Mandrone glacier forms the largest glacier mass in the Italian Alps. From the maximum Little Ice Age extension to present, these two glaciers lost about 36% of their total area. The seismic survey evidenced an ice thickness ranging from 170 m to 270 m and the presence of a relatively thick layer of sediments at the bottom. Comparison with previous investigations seems to indicate that, in the last 50 years, the ice thickness in the survey area has not significantly changed. This evidence is contrary to the general retreat trend and could be due to a sort of thermal inertia in this glacial accumulation area.

Geophysical potentials in glacial and periglacial environments in the Alps.

This study analyzes the historical series of precipitation fallen along Latian coast and Abruzzo coast, and extreme rainfall in the context of climate change. Daily precipitation data cover the years ranging from 1922 to 2009 for one meteorological station, and from 1951 to 2010 for five stations. We focus on the extreme values following two approaches: the first one is based on the maximum annual daily rainfall series (1-day, 2day and 3-day) for which suitable probability distributions are fitted. The second one is based on the series of peaks over annual thresholds (POT) for which the best fitting distribution is identified. The aim of this analysis is to estimate rainfall return levels for various return periods. This is particularly helpful to the Local Administration for the urban planning and for alerting residents in metropolitan areas.

A multidisciplinary approach to landslide modelling: the case of Campodenno, north-eastern Alps, Italy

Campodenno village, laying in the central-western part of the Trentino Region (Northern Italy), is affected by composite landslide phenomena that cause heavy damages to buildings and public facilities. The purpose of the present work was the definition of a complete geological model, to be used to perform stability analyses of sliding slopes. In order to carry out a valid slope stability analysis a complete and reliable geological and geotechnical model of the landslide slope must be performed. All the previous available data, then, have been collected and re-interpreted. The integration of all these data allowed the definition of a preliminary geological and geotechnical model of the slope that, however, resulted to be affected by some uncertainties as regards mainly the spatial distribution of different stratigraphical levels. Because of these uncertainties, some geophysical surveys have been carried out in order to investigate the lateral continuity and hydrogeological properties of the stratigraphic layers and also the thickness of the sliding material. Geoelectrical, seismic and magnetotelluric surveys have been carried on and the interpreted results compared and integrated with the already existing data. In that way, reliable geological models of the Campodenno slopes have been realized to be used for stability analysis purposes. RIASSUNTO: L’abitato di Campodenno, localizzato nella porzione centro-occidentale della regione Trentino (Italia settentrionale) su di una collina allungata in direzione NW-SE, è caratterizzato dalla presenza di fenomeni di instabilità compositi su entrambi i fianchi della collina, che provocano danni piuttosto importanti a costruzioni ed infrastrutture. La geologia locale è caratterizzata dalla presenza di un bedrock costituito da marne eoceniche fittamente stratificate, al di sopra delle quali si trova una spessa sequenza di depositi quaternari formata da tre livelli con differenti caratteristiche litologiche e, di conseguenza, geotecniche ed idrogeologiche. Le differenti proprietà dei suoli quaternari e la loro distribuzione spaziale danno origine ad una complessa e non completamente chiara struttura dei corpi idrici sotterranei. Lo scopo del presente lavoro è stato la definizione di un modello geologico e geotecnico completo ed affidabile, che potrà essere successivamente utilizzato per l’esecuzione delle analisi di stabilità dei versanti in studio. Tutti i dati disponibili sono stati quindi raccolti, analizzati e reinterpretati. L’integrazione di tali dati ha consentito la definizione di un modello geologico-tecnico preliminare dell’area in esame che, tuttavia, risulta affetto da notevoli incertezze legate principalmente alla distribuzione spaziale dei differenti livelli stratigrafici. A causa di tali incertezze, sono stati realizzati nuovi rilievi mediante metodi geofisici principalmente con il fine di investigare la continuità laterale dei corpi stratigrafici e lo spessore del materiale mobilizzabile dai fenomeni franosi in atto. I risultati dei sondaggi geoelettrici, sismici e magnetotellurici realizzati sono stati, quindi, confrontati ed integrati con i dati già esistenti. In questo modo è stato possibile ricostruire il modello geologico dell’area instabile da poter utilizzare nell’analisi delle condizioni di stabilità e nella scelta degli interventi sistematori. Key terms: geological modelling, landslide, geophysics methods, hydrogeology Termini chiave: modello geologico, frane, metodi geofisici, idrogeologia