Geology Geomorphology and Landslide
Total Page：16
File Type：pdf, Size：1020Kb
Programma Operativo Nazionale “Ricerca e Competitività 2007‐2013” Regioni Convergenza ASSE I ––SostegnoSostegno ai mutamenti strutturali Obiettivo Operativo: Aree scientifico‐tecnologiche generatrici di processi di trasformazione del sistema produttivo e creatrici di nuovi settori Azione: Interventi di sostegno della ricerca industriale GEOLOGY, GEOMORPHOLOGY AND LANDSLIDE SUCEPTIBILITY ALONG A HIGHWAY SECTION IN NORTHERN CALABRIA (ITALY) Working group: Francesco Muto1, Massimo Conforti2, Salvatore Critelli1, Davide Fabbricatore1, Luciana Filomena1, Teresa Pelle1, Valeria Rago1, Gaetano Robustelli1, Fabio Scarciglia1, Vincenzo Tripodi1 1 DiBEST-Università della Calabria, Arcavacata di Rende (CS), Italy 2 CNR–ISAFOM, Rende (CS), Italy Geological and Hydraulic Safety along Motorways and Railways Università della Calabria, Arcavacata di Rende (CS), 25 –26 November 2014 Aula Magna Cosenza Aims Sud Research project PON01-01503 “Integrated Systems for Hydrogeological Risk Monitoring, Early Warning and Mitigation Along the Main Lifelines” – Multidisciplinary approach Hydrogeological risk mitigation and early warning along 3 highway sections of southern Italy Assessment of landslide susceptibility along the A3 highway section between Cosenza Sud and Altilia in northern Calabria (~26 km) Altilia Geological and structural setting Carbonate rocks N‐S trending Savuto fault system (Mesozoic) Metamorphic rocks (Palaeozoic) Clay Unit (Upper Miocene) North Palaeozoic metamorphic and N‐S fault plutonic basement rocks Mesozoic to Paleogene ophiolitic, metasedimentary and sedimentary rocks Miocene to Quaternary Tansi et al. (2007) sedimentary cover Geomorphological features Geological, lithological and structural control; Weathering and morphodynamic processes Fault scarps, high local relief and stream incision, lateral and vertical juxtaposition of terrains with different behaviour in respect to erosion and mass movements COSENZA sud COSENZA sud Geological Lithological map map ALTILIA ‐ GRIMALDI ALTILIA ‐ GRIMALDI Geomorphological map COSENZA sud ALTILIA ‐ GRIMALDI Landslide inventory maps Legend Landslide scarp Active Dormant Inactive Landslide body Fall Slide Flow 1955 Complex PtPresent‐day Shallow landslide Landslides Calcarenite Sand and sandstone Sandstone and conglomerate Phyllite Altilia Altilia Sand (and soils) Gneiss Iassa Mancarelli Geological map Calcarenite Ogliara Sandstone Conglomerate Ogliara site Schist and phyllite Geological map Garcito Garcito Highway Piano d’Infante site Geological map Fiego Legend Sand (and soils) Road Scarp edge Gabions Highway Fiego Bulkhead piles site Soils Entisols Inceptisols Mollisols Alfisols Pedological discontinuities Fiego site F2 F3 Perched water table 10,0 15,0 20,0 25,0 30,0 35,0 40,0 0,0 505 10 15 20 25 30 35 40 45 50 , 0 0 5 GPI A GPI A GPI AB GPI AB GPI 2Bt1 GPI 2Bt1 GPI 2Bt2 GPI 2Bt2 F1 AB F1 AB F1 Bg1 F1 Bg1 F1 Btg2 F1 Btg2 F1 Bg3 F1 Bg3 F1 Bg4 F1 Bg4 Clay F1 CB F1 CB WL% (%) F2 2 A F2 2 A (%) F2 B/A F2 B/A F2 2Bt1 F2 2Bt1 F2 2Bt2 F2 2Bt2 Some F3 Bw F3 Bw F3 2Bt1 F3 2Bt1 F3 2Bt2 F3 2Bt2 physical and F3 2Btg3 F3 2Btg3 PD A Tasca PD A Tasca PD Bw PD Bw PD 2Bt1 PD 2Bt1 PD 2Bt2 PD 2Bt2 PD 2Bt3 PD 2Bt3 0,40 0,60 0,80 1,00 1,20 1,40 1,60 0,00 020 0 , 10 15 20 25 30 20 rheological data 0 5 GPI A IP GPI A GPI AB GPI AB GPI 2Bt1 = GPI 2Bt1 GPI 2Bt2 WL GPI 2Bt2 F1 AB - F1 AB F1 Bg1 F1 Bg1 WP F1 Btg2 F1 Btg2 BD F1 Bg3 F1 Bg3 ( F1 Bg4 F1 Bg4 ( F1 CB F1 CB g cm IP% F2 2 A F2 2 A ‐ F2 B/A F2 B/A 3 ) F2 2Bt1 ( F2 2Bt1 ( F2 2Bt2 F2 2Bt2 ρ a ) F3 Bw F3 Bw F3 2Bt1 F3 2Bt1 F3 2Bt2 F3 2Bt2 F3 2Btg3 F3 2Btg3 PD A Tasca PD A Tasca PD Bw PD Bw PD 2Bt1 PD 2Bt1 PD 2Bt2 PD 2Bt2 PD 2Bt3 PD 2Bt3 Landslide susceptibility map Conditional UCUs Analysis tors cc ItIntersec tion of predisposing Landslide factors susceptibility osing fa Training set map pp (50%) Landslides Predis Testing set Validation of landslide (50%) susceptibility map Thematic layers subdivided into classes UCU = Unique Condition Unit EtiEstima tion ofthf the proba bility to obta in a certitain ditdensity of lan ds lides per each UCU, i.e. the probability (%) that a landslide could occur in that specific area Landslide susceptibility map UCUs map construction 7030 UCUs Landslide susceptibility map Relationship between the UCUs map and the landslide map Landslide Training set Testing set Highway Landslide susceptibility map Distribution of susceptibility classes Validation of the susceptibility map Susceptibility class Susceptibility Landslide Area (()%) Low class testing set (%) Moderate Very high 933 High 80% Very high High 29 47 Highway Moderate 24 17 Low 38 3 Correct classification: most of the landslides is included in the 2 highest susceptibility classes High probability (80%) that a landslide could occur in the red-orange areas (The validation set mimics future landslides) Landslide spatial risk Independent of magnitude and Spatial risk class return period Low Susceptibility of landslides Moderate Low High Moderate Very High High Very high Highway Vulnerable objects (highway) are overlain on the susceptibility map Spatial Risk km % Very high 2.9 10.4 High 7.5 26.8 Moderate 828.2 29.4 Low 9.3 33.4 Relatively low spatial risk because vulnerable highway tracks are not included in higher‐risk areas or potential landslides will not involve them (e.g., viaducts) Conclusive remarks Prominent role of litho-structural (fault scarps, spatial arrangement of different lithologies) and geomorphological features (high local relief, steep slopes, stream dissection) as predisposing factors of landslides and their types Morphological and physical discontinuities caused on geological terrains by weathering and pedogenetic processes (soil horizon differentiation, argillification, oxidation, development of pedogenic structure, clay illuviation) interfingered with geomorphic dynamics (truncation by erosion, burial by younger sediments, e.g., colluvial material, slope deposits, landslide debris) Corresppgonding changes in ppyhysical and geomechanical ppproperties of rock types (e.g., particle size distribution, liquid and plastic limits, bulk density, organic carbon content, porosity) in depth, evidenced by laboratory analyses High reliability of the landslide susceptibility and spatial risk assessment along the pilot section of the A3 highway between Cosenza Sud and Altilia (N Calabria) using the UCUs (Unique Condition Units) method and the conditional analysis Thank you for your attention ! .