Massimiliano Nocentini

Exploitation of Amplitude and Phase of Satellite SAR Images for Landslide Mapping: The Case of Montescaglioso (South Italy)

Pre- event and event landslide deformations have been detected and measured for the landslide that occurred on 3 December 2013 on the south-western slope of the Montescaglioso village (Basilicata Region, southern Italy). In this paper, ground displacements have been mapped through an integrated analysis based on a series of high resolution SAR (Synthetic Aperture Radar) images acquired by the Italian constellation of satellites COSMO-SkyMed. Analysis has been performed by exploiting both phase (through multi-image SAR interferometry) and amplitude information (through speckle tracking techniques) of the satellite images. SAR Interferometry, applied to images taken before the event, revealed a general pre-event movement, in the order of a few mm/yr, in the south-western slope of the Montescaglioso village. Highest pre-event velocities, ranging between 8 and 12 mm/yr, have been recorded in the sector of the slope where the first movement of the landslide took place. Speckle tracking, applied to images acquired before and after the event, allowed the retrieval of the 3D deformation field produced by the landslide. It also showed that ground displacements produced by the landslide have a dominant SSW component, with values exceeding 10 m for large sectors of the landslide area, with local peaks of 20 m in its central and deposit areas. Two minor landslides with a dominant SSE direction, which were detected in the upper parts of the slope, likely also occurred as secondary phenomena as consequence of the SSW movement of the main Montescaglioso landslide.

Event scenario analysis for the design of rockslide countermeasures

The Torgiovannetto quarry (Assisi municipality, central Italy) is an example of a site where the natural equilibrium was altered by human activity, causing current slope instability phenomena which threaten two roadways important for the local transportation. The quarry front, having a height of about 140 m, is affected by a 182,000 m3 rockslide developed in intensely fractured limestone and is too large to be stabilized. In 2003 some tension cracks were detected in the vegetated area above the quarry upper sector. From then on, several monitoring campaigns were carried out by means of different instrumentations (topographic total station, extensometers, inclinometers, ground-based interferometric radar, laser scanner and infrared thermal camera), allowing researchers to accurately define the landslide area and volume. The latter’s major displacements are localized in the eastern sector. The deformational field appears to be related to the seasonal rainfall. The landslide hazard associated with the worst case scenario was evaluated in terms of magnitude, intensity and triggering mechanism. For the definition of the possible runout process the DAN 3D code was employed. The simulation results were used in order to design and construct a retaining embankment. Furthermore, in order to preserve both the safety of the personnel involved in its realization and of the roadways users, an early warning system was implemented. The early warning system is based on daily-averaged displacement velocity thresholds. The alarm level is reached if the prediction based on the methods of Saito (1969) and Fukuzono (1985) forecasts an imminent rupture.

The Calatabiano landslide (southern Italy): preliminary GB-InSAR monitoring data and remote 3D mapping

On 24 October 2015, following a period of heavy rainfall, a landslide occurred in the Calatabiano Municipality (Sicily Island, Southern Italy), causing the rupture of a water pipeline supplying water to the city of Messina. Following this event, approximately 250,000 inhabitants of the city suffered critical water shortages for several days. Consequently, on 6 November 2015, a state of emergency was declared (O.C.D.P. 295/2015) by the National Italian Department of Civil Protection (DPC). During the emergency management phase, a provisional by-pass, consisting of three 350-m long pipes passing through the landslide area, was constructed to restore water to the city. Furthermore, on 11 November 2015, a landslide remote-sensing monitoring system was installed with the following purposes: (i) analyse the landslide geomorphological and kinematic features in order to assess the residual landslide risk and (ii) support the early warning procedures needed to ensure the safety of the personnel involved in the by-pass construction and the landslide stabilization works. The monitoring system was based on the combined use of Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR) and terrestrial laser scanning (TLS). In this work, the preliminary results of the monitoring activities and a remote 3D map of the landslide area are presented.

Assessing the Capabilities of VHR Satellite Data for Debris Flow Mapping in the Machu Picchu Area (C101-1)

Machu Picchu is an ancient Inca city located on a narrow ridge, within the Andes, approximately 80 km north-west of Cusco, Peru. This site of exceptional cultural heritage and its related infrastructure are being undermined by rapid debris flows, that are related to the presence of thick debris deposits produced by granite weathering, past slides and climatic conditions. On 26 December 1995 a rock fall/debris flow occurred on the road that leads to the citadel (Carretera Hiram Bingham) interrupting the traffic coming from the railway station of Aguas Calientes, and on 10 April 2004 a major debris flow, channeled in the Alcamayo stream, devastated the village of Aguas Calientes, causing 11 casualties and damaging the railway. Within the framework of the International Consortium on Landslides (ICL) a program of monitoring the instability conditions at this site was undertaken. In this work the preliminary results of the field survey and the analysis of some very high resolution (VHR) satellite images are presented. A multi-temporal analysis of Quickbird satellite (from Digitalglobe©) panchromatic and multispectral data was carried out: an archive image dated 18 June 2002 was available while a new acquisition with a good image was obtained on 18 May 2004. The main purpose of the analysis was the reconnaissance of debris flows using remote sensing techniques. The remote sensing data analysis was integrated with a field survey, carried out in September 2004. This allowed us to confirm the interpretation of the images, to produce a detailed geomorphological map of the area around the Carretera Hiram Bingham and to assess the thickness of debris deposits on the slopes. The results constitute a first step towards a complete debris flow hazard assessment in the area, where the interactions between slope instability and land use can produce very critical conditions.

Monitoring the rapid-moving reactivation of earth flows by means of GB-InSAR: The April 2013 Capriglio Landslide (Northern Appennines, Italy)

This paper presents the main results of the GB-InSAR (ground based interferometric synthetic aperture radar) monitoring of the Capriglio landslide (Northern Apennines, Emilia Romagna Region, Italy), activated on 6 April 2013. The landslide, triggered by prolonged rainfall, is constituted by two main adjacent enlarging bodies with a roto-translational kinematics. They activated in sequence and subsequently joined into a large earth flow, channelizing downstream of the Bardea Creek, for a total length of about 3600 m. The displacement rate of this combined mass was quite high, so that the landslide toe evolved with velocities of several tens of meters per day (with peaks of 70–80 m/day) in the first month, and of several meters per day (with peaks of 13–14 m/day) from early May to mid-July 2013. In the crown area, the landslide completely destroyed a 450 m sector of provincial roadway S.P. 101, and its retrogression tendency exposed the villages of Capriglio and Pianestolla, located in the upper watershed area of the Bardea Creek, to great danger. Furthermore, the advancing toe seriously threatened the Antria bridge, representing the “Massese” provincial roadway S.P. 665R transect over the Bardea Creek, the only strategic roadway left able to connect the above-mentioned villages. With the final aim of supporting local authorities in the hazard assessment and risk management during the emergency phase, on 4 May 2013 aerial optical surveys were conducted to accurately map the landslide extension and evolution. Moreover, a GB-InSAR monitoring campaign was started in order to assess displacements of the whole landslide area. The versatility and flexibility of the GB-InSAR sensors allowed acquiring data with two different configurations, designed and set up to continuously retrieve information on the landslide movement rates (both in its upper slow-moving sectors and in its fast-moving toe). The first acquisition mode revealed that the Capriglio and Pianestolla villages were affected by minor displacements (at an order of magnitude of a few millimeters per month). The second acquisition mode allowed to acquire data every 28 seconds, reaching very high temporal resolution values by applying the GB-InSAR technique.

Verifica delle condizioni di sicurezza della S.P. Lodovica in seguito ai fenomeni di crollo nella cava di Sesto di Moriano (Lucca)

On October 28th 2004 a rockfall took place next to the northern limit of the limestone quarry “Bertolucci e Fiore”, near Sesto di Moriano (Lucca). After this event, some minor rockfalls developed in the quarry, with a total volume of more than 30 000 m. The rock mass around the detachment zone is heavily fractured, with several huge blocks hanging in unstable conditions and threatening the regional road “Lodovica”, which is located immediately downslope from the quarry area. Since this is a very important route, we carried out investigations to assess the safety conditions of the road. These investigations include: 1) field trips to evaluate the extent of the unstable area, the volume of the involved material, and to recognize the failure or detachment mechanisms of the rock mass; 2) execution of a high resolution digital elevation model (DEM) of the rock face and the quarry floor using a high accuracy and long range 3D laser scanner. This technique allowed us to define the overall morphology of the area and the mean and maximum size of the rock blocks; 3) in situ rockfall simulations to evaluate rockfall runout, velocity and bounce height and to estimate the coefficients of restitution; 4) 2D numerical simulations of rockfalls along 5 profiles derived from the new DEM, performed by using two different methods (lumped mass and CRSP) in order to forecast the runout, the velocities, the bounce heights and the possible impact energy on the defence barriers. Based on numerical and in situ simulations, blocks were expected to collide with significant energy against the defence barrier only at its northern limit. After the critical section of the barrier was strengthened it was possible to assess that the risk for the “Lodovica” road was sufficiently low, and the road was again opened to traffic on December 24th, 2004. Key terms: Quarry, rockfall, laser scanner DEM, rockfall simulation Termini chiave: Cava, frana di crollo, laser scanner DEM, simulazioni caduta massi

Monitoring of the vibration induced on the Arno masonry embankment wall by the conservation works after the May 25, 2016 riverbank landslide

BackgroundThe concepts of disaster risk reduction and disaster risk management involve the development, improvement, and application of policies, strategies, and practices to minimize disaster risks throughout society. Nowadays, preserving architectural heritage and ancient monuments from disasters is an important issue in the cultural life of modern societies. The “health” of a building/structure may be evaluate by its deterioration or damage level: monitor the aging and promptly detect relevant damages, play a central role, and structure dynamic characterization and microtremor analysis are considered powerful techniques in this field. A wide bibliography about structures/buildings seismic dynamic characterization is counterpoised to a missing one about their seismic response during conservation/safety works. This paper focus on the seismic response and monitoring of a historical masonry embankment wall during the conservation works carried out after a riverbank landslide that seriously damaged it.ResultsThe H/V results of the acquired traces show that main resonance frequency of the masonry embankment wall is between 4 Hz and 15 Hz, in agreement with the frequency range of roughly 10-meters-high, squat and monolithic structure. The whole monitoring period can be divided into three intervals corresponding to three different kind of workings: i) piling work; ii) parapet breakdown, excavation, embankment arrangement and foot wall consolidation; iii) backfill and restoring of the original condition, ordinary construction activities. The maximum peak component particle velocity substantial increase during the second period. All the stations have a higher energy content in the 10-20 Hz frequency range, but the spectra analysis clearly shows that the NS component, perpendicular to the wall, is the most stressed one. Moreover, despite the considerable distance from the August 24 Central Italy earthquake epicentre, the earthquake waveform is clearly recognizable at each station. In fact, the energy is focused around 2 Hz and the signals show directivity neither for the spectrum nor for the H/V.ConclusionThis work may contribute to characterize the vibrations induced by piling work at close range, and help to define the maximum acceptable vibration pattern for such structures, since literature is missing of such case studies. The maximum peak component particle velocity values clearly showed the work advancement. This paper also shows how the H/V technique is a valuable method to estimate the resonant frequency not only of buildings, but also of a squat and monolithic structure like the Lungarno Torrigiani masonry embankment wall.

Remote Sensing Mapping and Monitoring of the Capriglio Landslide (Parma Province, Northern Italy)

Open image in new window In the spring of 2013, the Parma Province (Northern Italy) was affected by a large number of landslides, as a result of heavy and persistent rainfall occurred between January and April. This resulted in the triggering of about 1400 mapped landslides, which caused severe damages. In particular, on April 6th 2013, a large landslide activated in Tizzano Val Parma municipality. It stretches from an altitude of 980 m to about 630 m a.s.l., covering an area of 0.92 km2 with a total length of 3600 m. It is constituted by two main adjacent enlarging bodies with a roto-translational kinematics, channelizing downstream the Bardea Creek, forming an earth flow. The landslide crown area destroyed a 450 m-long sector of a provincial roadway, and its retrogression tendency put at risk the Capriglio and Pianestolla villages, located in the upper watershed area of the Bardea river. Moreover, the advancing toe threatened the Antria bridge, representing the “Massese” provincial roadway transect over the Bardea Creek. This work describes the main results of the landslide mapping and monitoring activities, conducted after the landslide trigger. With the aim of supporting local authorities in the hazard assessment and risk management, an integrated analysis of various remote sensing data was developed, in order to generate a multi-temporal mapping of the landslide, whose velocity reached values of several tens of meters per day in the first month, and several meters per day from early May to mid-July 2013. Satellite and aerial post-event images were analyzed, together with the results of field surveys, to accurately map the landslide extension and evolution. Moreover, on May 2013, a GB-InSAR (Ground Based Interferometric Synthetic Aperture Radar) monitoring campaign was started in order to assess displacements of the whole landslide area and to support early warning activities. The GB-InSAR acquired until December 2013.

Remote 3D Mapping and GB-InSAR Monitoring of the Calatabiano Landslide (Southern Italy)

Open image in new window On October 24th 2015, following a period of heavy rainfall, a landslide triggered in the Calatabiano Municipality (Sicily Island, Southern Italy) causing the rupture of a water pipeline transect of the aqueduct supplying water to the city of Messina. This event, caused critical water shortages for several days to a large part of the city inhabitants. In order to restore the city water supplies, a provisional by-pass, consisting of three 350 m long pipes passing through the landslide area, was carried out. On November 11th 2015, a landslide monitoring system was installed, based on the combined use of advanced remote sensing techniques such as Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR), Terrestrial Laser Scanning (TLS) and Infrared Thermography (IRT). The installed monitoring system allowed to: (i) analyze the landslide geomorphological and kinematic features in order to assess the landslide residual risk; (ii) support the early warning procedures needed to ensure the safety of the personnel involved in the by-pass realization and the landslide stabilization works. In this work, the preliminary results of the monitoring activities and a 3-D mapping of the landslide area are presented.

Mapping Rapid-Moving Landslide with Satellite SAR Images: The Case of Montescaglioso (South Italy)

Pre-event and event landslide deformations have been detected and measured for the landslide that occurred on December 3rd, 2013 on the south-western slope of the Montescaglioso village (Basilicata Region, Southern Italy). The event, triggered by 56 h of continuous rainfalls, produced a ground displacement of several meters and created significant damages to buildings and local infrastructures. Ground displacements have been mapped through an integrated analysis based on a series of high resolution SAR (Synthetic Aperture Radar) images acquired by the Italian constellation of satellites COSMO-SkyMed. The purpose of this mapping activity was twofold: (i) detect and record any pre-event deformation in and around the village of Montescaglioso, through the use of multi-image SAR interferometry, suitable for mapping slow deformation phenomena and (ii) map and measure any surface changes produced by the 3rd December landslide, using amplitude-based method, suitable for mapping much faster displacements. SAR Interferometry, applied to images taken before the event, revealed a general pre-event movement, in the order of a few mm/year, in the south-western slope of the Montescaglioso village, with highest velocities in the sector of the slope where the first movement of the landslide took place. Amplitude analysis allowed the retrieval of the three components of the landslide deformation field, with values exceeding 10 m for large sectors of the landslide area and local peaks of 20 m in its central and deposit areas. The synergistic exploitation of phase and amplitude of SAR images turned out to be a powerful tool for landslide investigation, allowing the detection of slow, precursory deformation patterns as well the retrieval of full 3D surface displacement fields caused by large, rapid-moving landslides.