tiziana apuani

Università degli Studi di Milano - State University of Milan (Italy), Dipartimento di Scienze della Terra "A. Desio", Faculty Member

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Papers by tiziana apuani

Integration of Geological Surveys and 3D Laser Scanner Techniques in Heritage Sites: How Did Palazzo Belfort Survive the Catastrophic 1618 Piuro Landslide?

Advances in Science, Technology & Innovation/Advances in science, technology & innovation, 2024

Mapping landscape evolution in 3D: Climate change, natural hazard and human settlements across the 1618 Piuro landslide in the Italian Central Alps

Earth Surface Processes and Landforms, Nov 29, 2023

Simulating wildland surface fire behaviour to support emergency management

Imprensa da Universidade de Coimbra eBooks, 2022

The recent upsurge in the incidence of extreme wildfire events, the expected impact of climate ch... more The recent upsurge in the incidence of extreme wildfire events, the expected impact of climate change on the frequency and severity of fires, and the progressive expansion of wildland-urban interface areas highlight the tangible need for improvement in our ability to predict, mitigate and manage the growing risk to which communities are exposed. The aim of this research is to contribute to deepen the knowledge on the spatial simulation of the complex dynamics of wildland surface fire behaviour through the development and application of a spatially distributed predictive model for the simulation of wildland surface fire spread intended for operational purposes. Given the position of one or more ignition points, the developed model allows to (i) obtain near real time dynamic estimates of the geo-environmental parameters that control the fire spread, (ii) compute the direction and intensity of the maximum rate of fire spread in heterogeneous environments, and (iii) simulate the surface fire spread using agent-based models. The final aim is to provide competent authorities with timely information on the expected evolution of the flame front to optimise decisionmaking processes. The model, developed under synthetic conditions, is then applied to case studies recorded in the territory of the Autonomous Region of Sardinia, that offers institutional information on the ignition location, the evolution of the flame front, and the completed fire suppression activities, which are implemented in the model as well. Overall, the model showed a promising predictive capacity evaluated in quantitative terms of morphological matching between the observed and predicted fire spread patterns, returning more accurate results in areas with less complex morphologies and dominated by herbaceous rather than shrubby fuels. The model also made it possible to obtain simulations with processing times compatible with its operational application as a tool for optimising and planning fire risk prevention and mitigation strategies and policies as well as fire management activities. Future research will be aimed at estimating the propagation of the parametric uncertainty through the model and applying the model to fire events occurred across different Mediterranean-type climate regions to consistently evaluate its predictive capacity.

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The Rock Engineering System (RES) applied to landslide susceptibility zonation of the northeastern flank of Etna: methodological approach and results

EGU General Assembly Conference Abstracts, Apr 1, 2015

Ground deformations in the northeastern flank of Etna are well known. Despite only a few landslid... more Ground deformations in the northeastern flank of Etna are well known. Despite only a few landslide events have been documented, these have significantly involved and damaged lifelines and buildings. These events are mainly related to the activity of the volcano-tectonic structures and associated seismicity, as in the case of the 2002 reactivation of the Presa landslide during an increased activity of the Pernicana fault system. In order to highlight the areal distribution of potentially unstable slopes based on a detailed, site-specific study of the factors responsible for landslide, and to ultimately contribute to risk management, a landslide susceptibility analysis of the northeastern flank of Etna in the Pernicana area was carried out, and a susceptibility map at 1:10.000 scale was produced, extending over an area of 168 km2. Different methods are proposed in the literature to obtain the regional distribution of potentially unstable slopes, depending on the problem scale, the slope dynamic evolution in the geological context, and the availability of data. Among semi-quantitative approaches, the present research combines the Rock Engineering System (RES) methodology with parameter zonation mapping in a GIS environment. The RES method represents a structured approach to manage a high number of interacting factors involved in the instability problem. A numerically coded, site-specific interaction matrix (IM) analyzes the cause-effect relationship in these factors, and calculates the degree of interactivity of each parameter, normalized by the overall interactivity of the system (weight factor). In the specific Etna case, the considered parameters are: slope attitude, lithotechnical properties (lithology, structural complexity, soil and rock mass quality), land use, tectonic structures, seismic activity (horizontal acceleration) and hydrogeological conditions (groundwater and drainage). Thematic maps are prepared at 1:10.000 scale for each of these parameters, and instability-related numerical ratings are assigned to classes. An instability index map is then produced by assigning, to each areal elementary cell (in our case a 10 m pixel), the sum of the products of each weight factor to the normalized parameter rating coming from each input zonation map. This map is then opportunely classified in landslide susceptibility classes (expressed as a percentage), enabling to discriminate areas prone to instability. Overall, the study area is characterized by a low propensity to slope instability. Few areas have an instability index of more than 45% of the theoretical maximum imposed by the matrix. These are located in the few steep slopes associated with active faults, and strongly depending on the seismic activity. Some other areas correspond to limited outcrops characterized by significantly reduced lithotechnical properties (low shear strength). The produced susceptibility map combines the application of the RES with the parameter zonation, following methodology which had never been applied up to now in in active volcanic environments. The comparison of the results with the ground deformation evidence coming from monitoring networks suggests the validity of the approach

Parametrization of a dry retaining wall on a terraced slope in Valtellina (Northern Italy) and stability analysis

The mechanical characterization of dry retaining walls is a key issue for the stability analysis ... more The mechanical characterization of dry retaining walls is a key issue for the stability analysis of slopes in Valtellina, where vineyard cultivated terraces have already been involved in rapid mass movements. The study presents the solution adopted to approach the problem by numerical modelling, focusing on the difficulties in the parameterization of dry walls. While geotechnical field and laboratory measurements allow to define the backfill soil properties following conventional procedures, no standards are proposed for dry walls. In this study, walls are likened to equivalent rock masses, where blocks with different shapes and dimensions are separated by "discontinuities" characterized by aperture, filling and roughness. Direct observations and images analysis allowed to assign a Geological Strength Index to the walls, applying the Hoek & Brown criterion, and to calculate the wall equivalent values of cohesion and friction angle. The performed stability analysis is supported by a previous hydrological model, which allows to define a temporary perched groundwater level when a rainfall is simulated. The infiltration phase was calibrated and validated comparing the in situ water levels, recorded by continuous piezometric datalogger, with the simulated ones, using as input the rainfalls registered by a local meteorological station. Two different rainfall scenarios were then reproduced, with similar duration and return period: the former caused three mass movements in 1983 while the latter had no instability consequences. Once the hydrological models were reconstructed, the stress-strain modeling was performed to verify the worth of the geomechanical parameters assigned to the wall, and eventually to calibrate them. The present work emphasizes the importance of direct measurements and monitoring activities to develop reliable conceptual models for numerical analysis of groundwater flow and stability in an anthropogenic impacted geological context. Moreover it highlights the importance of field measures to reduce the uncertainty of parameters that are almost impossible to be measured directly.

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Development of a 3D numerical model to evaluate the Stromboli NW flank instability in relation to magma intrusion

EGUGA, Apr 1, 2009

A stress-strain analysis of the Stromboli volcano was performed using a three-dimensional explici... more A stress-strain analysis of the Stromboli volcano was performed using a three-dimensional explicit finite difference numerical code (FLAC 3D, ITASCA, 2005), to evaluate the effects associated to the presence of magma pressure in magmatic conduit and to foresee the evolution of the magmatic feeding complex. The simulations considered both the ordinary state for the Stromboli, characterized by a partial fill of the active dyke with regular emission of gas and lava fountains and the paroxysmal conditions observed during the March 2007's eruptive crisis, with the magma level in the active dyke reaching the topographic surface along the Sciara del Fuoco depression. The modeling contributes to identify the most probable directions of propagation of new dikes, and the effects of their propagation on the stability of the volcano edifice. The numerical model extends 6 x 6 x 2.6 km3, with a mesh resolution of 100 m, adjusting the grid to fit the shape of the object to be modeled. An elasto-plastic constitutive law was adopted and an homogeneous Mohr-Coulomb strength criterion was chosen for the volcanic cone, assuming one lithotechnical unit (alternation of lava and breccia layers "lava-breccia unit"- Apuani et al 2005). The dykes are represented as discontinuities of the grid, and are modeled by means of interfaces. The magmatic pressure is imposed to the model as normal pressure applied on both sides of the interfaces. The magmastatic pressure was calculated as Pm=d•h, where d is the magma unit weight assumed equal to 25 KN/m3, and h (m) is the height of the magma column. Values of overpressure between 0 and 1 MPa were added to simulate the paroxysmal eruption. The simulation was implemented in successive stages, assuming the results of the previous stages as condition for the next one. A progressive propagation of the dike was simulated, in accordance with the stress conditions identified step by step, and in accordance with the evidences detected by in situ survey, and by means of the National Institute for Geophysics and Volcanology (INGV)-National Civil Protection Department (DPC), monitoring system. The results are expressed in terms of deformations and shear strain increments. The much unstable portion of the Sciara depression is evidenced by the highest value of the shear strain increments and is located on its upper right portion. The strain distribution is coherent with the ground motion recorded by the GB-InSAR monitoring system installed by the University of Florence thanks to the INGV-DPC 2004-2006 research program. Superficial displacements of metric amount are developed in this sector and indicate local instability, but are not sufficient to expect deep seated collapse of the volcano's flanks. A mechanism for sub horizontal sill intrusion starting from a vertical dike was proposed, and modelled, to explain the formation of the eruptive vent appeared on the Sciara slope at an altitude of about 400 meters a.s.l.. The results indicate an highly stressed and disturbed band extended transversally to the Sciara at the same elevation; furthermore the maximum value of the shear strain increments is located in correspondence with the actual position of the eruptive vents. The obtained results are very coherent with the field evidences, and could represent one possible explanation of the observed 2007 events.

Comparison of the results of different scale hydrogeological models on a terraced slope of Valtellina (Northern Italy)

EGUGA, Apr 1, 2012

How to model the stability of terraced slopes? : the case study of Tresenda (northern Italy)

EGU General Assembly Conference Abstracts, Apr 15, 2015

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A comparison between univariate probabilistic and multivariate (logistic regression) methods for landslide susceptibility analysis: the example of the Febbraro valley (Northern Alps, Italy)

EGUGA, Apr 1, 2009

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Geological and geotechnical characterization of the debris avalanche and pyroclastic deposits of Cotopaxi Volcano (Ecuador). A contribute to instability-related hazard studies

Journal of Volcanology and Geothermal Research, Feb 1, 2017

Geological and geotechnical characterization of the debris avalanche and pyroclastic deposits of ... more

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A Machine Learning Model for Predicting Wildland Surface Fire Spread According to Rothemel’s Equations

This article is an open access article distributed under the terms and conditions of the Creative... more

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A novel dynamic rockfall susceptibility model including precipitation, temperature and snowmelt predictors: a case study in Aosta Valley (northern Italy)

Landslides, Jun 6, 2023

The overarching goal of the study was the development of a potentially dynamic rockfall susceptib... more The overarching goal of the study was the development of a potentially dynamic rockfall susceptibility model by including climate predictors. The work is based on previously defined critical thresholds relating three climate indices-effective water inputs (EWI), wet-dry cycles (WD) and freeze-thaw cycles (FT)-and rockfall occurrence. The pilot area is located in the Aosta Valley region (Italian Western Alps). The susceptibility model settings were optimized through a stepwise procedure, carried out by means of generalized additive models (GAM). Predictors included topographic, climatic and additional snow-related variables. As climatic predictors, the mean annual threshold exceedance frequency was calculated for each index. All models were developed including an automatic penalization of statistically non-significant variables (i.e. shrinkage). The initial susceptibility model was set without considering potential inventory bias. Secondly, a "visibility mask" was produced to limit the modelling domain according to the rockfall event census procedures. Thirdly, GAMs functional relationships were analysed to verify the physical plausibility of predictors. Finally, to reduce concurvity, a principal component analysis (PCA) including climatic and snow-related predictors was carried out. Key findings were as follows: (i) ignoring inventory bias led to excellent model performance but to physically implausible outputs; (ii) the selection of non-rockfall points inside a "visibility mask" is effective in managing inventory bias influence on outputs; (iii) the inclusion of climate predictors resulted in an improvement of the physical interpretability of the associated models and susceptibility maps, being EWI, WD and the maximum cumulated snow melting the most important physically plausible climate predictors; (iv) the PCA strategy can efficiently reduce model concurvity.

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Quantitative risk assessment using vulnerability functions from debris flow event reconstruction : poster

A thermo-mechanical numerical approach for the analysis of a historical rockslide in the Italian Alps

IOP conference series, Aug 1, 2021

In this work, a thermo-mechanical (TM) numerical approach is presented and applied to investigate... more In this work, a thermo-mechanical (TM) numerical approach is presented and applied to investigate the stress-strain evolution of an alpine rock-slope located in the Central Italian Alps (Sondrio Province). Along the "Cimaganda" slope a massive rockslide event occurred around 900 A.D. mobilizing an estimated volume of 7.5 Mm 3 of material, and reaching the bottom of the valley. Interest in this historic event was raised again in recent times, as a new rockslide took place in 2012, mobilizing 20.000 m 3 of rock material and blocking the SS36 National Road. To understand the general evolution of the Cimaganda rock slope, the recent geomorphological history of the Valley (post Last Glacial Maximum) was considered. In particular, to explore how glacial loading and unloading, associated with thermo-mechanical processes can promote rock mass damage, a 2D DEM numerical approach was adopted, calibrated upon the collected experimental and field data, and supported by a 2D FEM analysis to simulate transient heat diffusion over the Valley cross-section due to ice retreat and paleo-temperature evolution. Results show a clear relation between TM stresses and the occurrence of rock-mass damage and slip propagation along discontinuities. Simulated displacement and the development of a deep region of shear strain localization, allow to highlight the significance of temperature influence in preparing the rock slope to instability.

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Mechanical characterization of the Sergnano reservoir by ultrasonic wave velocity measurements

Geomechanical surveys and geostatistical analyses in Valchiavenna (Italian Central Alps)

The present study deals with the forecast of geomechanical features in rock masses, out from surv... more The present study deals with the forecast of geomechanical features in rock masses, out from survey points, and how mechanical properties can be regarded as regionalized variables. It considers an area of about 200 km 2 , located in the Italian Central Alps, along the San Giacomo Valley (SO), where different civil and mining works are present. The regional geological setting is related to the Pennidic Nappe arrangement, characterized by the emplacement of sub-horizontal gneissic bodies, separated by a metasedimentary cover unit. Almost one hundred geomechanical field surveys were carried out in order to characterize the rock masses, in accordance with the I.S.R.M. suggested methods. This procedure allowed to identify the number of joint sets and their average orientations, supplying a quantitative description of the discontinuities in terms of spacing, persistence, roughness, aperture, filling, wall strength, weathering and moisture conditions. From collected data, the rock mass quality indexes were evaluated in each surveyed site. Geostatistical methods were applied to study the spatial distribution of main rock mass characteristics, such as the horizontal intercept and the Volumetric Joint Count, being the direct survey data local. Where no data were available the rock mass features were estimated; the results obtained by kriging and conditional simulation techniques are here presented and compared.

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Hydro-geotechnical modelling of subsidence in the Como urban area

Engineering Geology, Jul 1, 2019

The urban area of Como (Italy) is particularly susceptible to subsidence. The reason is the parti... more The urban area of Como (Italy) is particularly susceptible to subsidence. The reason is the particular structure of the subsoil, combined with the anthropic modification of the lakeshore lands linked to the historical evolution of the area. Moreover, this phenomenon exposes the lakefront areas to an increasing risk of flooding. The primary purpose of this study was to develop an effective methodology for the assessment of subsidence in urban areas, to be used as a support in groundwater management. The development of a coupled hydrogeological-geotechnical numerical model for the period 2004-2011 allowed recognizing the shoreline results as most susceptible areas to the phenomenon. Model results were critically evaluated through comparison with time series of PSInSAR and high precision levelling data available in the area. The anthropic perturbations of groundwater flow linked to the construction of lake flooding defenses in 2008-2009, enhanced the subsidence phenomenon in a localized area, pointing out the strong interdependence of groundwater circulation, lake level oscillations and geotechnical behavior of soils. Thus, the model revealed the most critical zones and geotechnical units, demonstrating to be a potential powerful tool to predict subsidence scenarios (e.g. the future completion of the floods defense works in the shoreline area).

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AMALPI trek: a geocultural trail from Maloja to St. Gotthard to increase the awareness of natural hazard in mountain settings

The historical evolution of a territory is usually related to its geological features and geomorp... more The historical evolution of a territory is usually related to its geological features and geomorphological dynamics. Floods and slope instabilities modify the landscape impacting on human life. The perception of the value of natural resources in mountain area and the culture of respect is an essential component in strategies aimed at ensuring the population a future of well-being, social and economic growing.The AMALPI Trek takes its name from the A.M.AL.PI.18 Project [1], which is the Italian acronymous for “Moving Alps, and Movements in the Alps”, developed in the framework of the European funded Interreg Italy-Switzerland Cooperation Program V-A 2014-2020. The project aims to encourage an innovative strategy for the promotion of natural and cultural heritage in the Alpine area from Maloja to St. Gotthard (through Val Bregaglia, Valchiavenna, Regione Moesa and Alto Ticino), even by the creation of a cross-border geo-cultural trail connecting sites which have experienced important geomorphological and anthropic changes due to the occurrence of landslides of great social impact. The trail is addressed to a scientific-cultural and educational tourism, to raise the perception of landscape components in the framework of the “total history”, composed by the geo(morpho)logical, bioecological and historic-cultural heritages. Placed in a central position, the AMALPI Center (scheduled to open mid-2023 in Chiavenna), will be a study and research hub on large landslides, reference for school activities and promotion events. In addition, an open access hiking guidebook and map will lead the trekker to discover tools and methods that allow the comprehension of past and ongoing processes, with the help of illustrative panels describing the main patrimonial aspects of the territory, which is rich in historical palaces, archaeological sites, and natural monuments.The AMALPI Trek runs through 10 Alpine valleys and crosses 7 mountain passes, for a total of about 150 km, plus several thematic itineraries that branch out of the main trail. Along the way, 19 large landslides of different age and type are touched. In many segments, the AMALPI trek follows historical trade routes, used in the past for the exchange of silk and soapstone products. There are some links between large landslides and stone resources typical of these mountains. A striking example are the “crotti”, natural caves used as cellars, perfect places for the storage of foods and other goods, and the “trone”, local soapstone caves, both generated by the gravitational accumulation of cyclopean boulders. The petrographic features of soapstone outcropping rock offer then a good workability, but locally they become weakness planes predisposing sliding.Looking at the causes and effects of landslide events, the trekker accrues the perception of human vulnerability to natural hazard, but it is also invited to discover how to prevent, mitigate, and manage hillslope dynamic to develop a sustainable and fulfilling life in mountain areas. [1] Interreg V-A Italy-Switzerland 2014-2020 Cooperation Program, Axis II “Cultural and natural enhancement”). Project ID 594274, “A.M.AL.PI. 2018 – Alpi in Movimento, Movimento nelle Alpi. Piuro1618–2018”.https://progetti.interreg-italiasvizzera.eu/it/b/78/alpiinmovimentomovimentonellealpipiuro

Wildfire behaviour modelling for wildfire hazard characterization: an Earth Observation application

Living Planet Symposium, May 17, 2019

The study is intended as a contribution to the developement of a wildfire behaviour modelling met... more The study is intended as a contribution to the developement of a wildfire behaviour modelling methodology effective in wildfire hazard characterization on a local scale and providing an appropriate scientific information available in decision making processes for wildfire management. Satellite sensor technologies has been investigated in order to acquire updated and reliable input data with a suitable spatial and temporal resolution. The modelling methodology has been validated and calibrated to past events recorded in wildland fire databases of Umbria and Sardinia Regions. Afterwards, an heuristic local research method has been implemented to optimize the accuracy of the models and to estimate their predictive capacity

The Cimaganda landslide (SO) : hydro-mechanical numerical modelling

Study area Ortogneiss-Tambò nappe Paragneiss-Tambò nappe Bregaglia valley Chiavenna valley San Gi... more Study area Ortogneiss-Tambò nappe Paragneiss-Tambò nappe Bregaglia valley Chiavenna valley San Giacomo valley The Cimaganda landslide (SO): hydro-mechanical numerical modelling Schists-cover unit Cimaganda landslide Geological framework The 2012 event represent the recent evolution of the historical Cimaganda rock avalanche which mobilized about 7.5 Mm 3 of material The Cimaganda landslide (SO): hydro-mechanical numerical modelling Ancient rock avalanche 2012 event Cimaganda village  Steep slopes with high sub-vertical rock cliffs  Frequent rockfalls and instability events Cimaganda landslide Geomorphological features Case study approach Working flowchart OBJECTIVE: ANALIZE SLOPE EVOLUTION USING NUMERICAL MODELS The Cimaganda landslide (SO): hydro-mechanical numerical modelling

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