Abstract
The site investigation of low-gradient slopes composed by marly rocks usually focuses on shallow slides in weathered mantling material as it is assumed that the underlying bedrock has higher strength, but deeper investigations may reveal larger, active, deep-seated movements. A typical example of this is found in Montemartano (Perugia, Central Italy). Here aerial photo interpretation and field observations indicate that active movements involve the shallower portion of the slope, formed by a very old and large landslide body extending over an area of about 0.5 km2. Borehole core logging and probe inclinometer monitoring reveal that the area corresponding to the deep-seated landslide is moving at a maximum rate of 70 mm/year down to a maximum depth of 40 m. A comparison of inclinometer and piezometer data indicates that the movement seasonally reactivates even when rainfall and piezometer levels are below average values and suggests that structural setting of the whole slope influences both groundwater flow and movement kinematics. This hypothesis is reinforced by seepage analyses and stability analyses yielding a mobilized shear strength close to residual strength of the clayey interbeds of the marly limestone formations. This implies that instability occurs along bedding over a large part of the slide. The importance of these phenomena in land management policy is discussed and the critical aspects of their investigation and monitoring are addressed. The reconstruction of landslide geometry/stratigraphy and geotechnical characterization of the materials is closely considered, particularly as these are complicated by the limited representativeness of field and laboratory investigations in this type of material.
Similar content being viewed by others
References
AGI (1979) Some Italian experiences on the mechanical characterization of structurally complex formations. Proceedings of the 4th International Congress on Rock Mechanics. Montreux 1:827–846
Amorosi A, Coccioni R, Tateo F (1994) The volcaniclastic bodies of the Lower Miocene Bisciaro Formation (Umbria–Marche Apennines). Giornale di Geologia 56(1):33–46
ASTM D4318-10 “Standard test methods for liquid limit, plastic limit, and plasticity index of soils”, ASTM International, West Conshohocken, PA, doi:10.1520/D4318-10
Barchi M (1991) Una Sezione Geologica bilanciata attraverso il settore meridionale dell’Appennino Umbro–Marchigiana: L’Acquasparta-Spoleto-Accumoli. Studi Geologici Camerti 1991/1:347–362, in Italian
Barchi M, Capitani M, Pazzaglia F, Sotera M (2004) Note illustrative del rilevamento geologico finalizzato al consolidamento dell'area in frana di "Montemartano", nel Comune di Spoleto. Unpublished report for Spoleto Municipality (in Italian)
Balducci M, Faralli L, Venanti LD, Olivanti C (2013) The large Acqualoreto (TR) landslide: stabilization projects through integrated use of consolidates and innovative techniques. In: Margottini C, Canuti P, Sassa K (eds) Landslide Science and Practice, 6:667–673, Springer, Berlin, doi:10.1007/978-3-642-31319-6_85
Bell FG (2000) Engineering Geology of Soils and Rocks. Blackwell Science, 482 pp
Brozzetti F, Lavecchia G (1995) Evoluzione del campo degli sforzi e storia deformativa nell’area dei Monti Martani (Umbria). Boll Soc Geol Ital 114:155–176 (in Italian)
Canuti P, Marcucci E, Trastulli S, Ventura P, Vincenti G (1986) Studi per la stabilizzazione della frana di Assisi. Proc. XVI Convegno Nazionale di Geotecnica. Bologna 1:165–174, in Italian
Cattuto C (1991) Sorgenti di Montemartano. Possibile miglioramento della captazione. Unpublished report for A.S.E.M. - Spoleto (in Italian)
Cruden DM, Varnes DJ (1996) Landslide types and processes. In Special Report 247: Landslides: investigation and mitigation. Transportation Research Board, Washington DC
Dobrin MB, Savit CH (1988) Introduction to geophysical prospecting, 4th edn. McGraw-Hill, Singapore, p 867
Fanti F (2006) Slope instability of San Miniato hill (Florence, Italy): possible deformation patterns. Landslides 3:323–330
IRPI (2001) General description and hazard situation for the Montemartano site. Piano per l’assetto Idrogeologico del Bacino del Fiume Tevere (in Italian)
ISO (2005) Geotechnical investigation and testing—field testing—part 2: dynamic probing (EN ISO 22476–2:2005)
Iverson RM, Major JJ (1987) Rainfall, ground-water flow, and seasonal movement at Minor Creek landslide, northwestern California: physical interpretation of empirical relations. Geol Soc Am Bull 99(4):579–594
Lo Presti D, Puci I (2001) Impiego delle prove penetrometriche dinamiche per la caratterizzazione meccanica dei terreni. XVIII Ciclo di Conferenze di Geotecnica di Torino, 48 pp, (in Italian)
Meinzer OE (1942) Hydrology. Mc Graw Hill, New York
Mansour MF, Morgenstern NR, Martin CD (2011) Expected damage from displacement of slow-moving slides. Landslides 7(1):117–131
Meigh AC (1977) General report—techniques of exploration, sampling & testing, including field tests, in structurally complex formations. International Symposium “The Geotechnics of Structurally Complex Formations”, Capri. Associazione Geotecnica Italiana 2:238–254
Monnet J, Fabre D, Zielinski M (2011) Les “Terres Noires” du Dauphine, un cas de roche tres sensible aux variations climatiques. Proceedings of the XV European Conference on Soil Mechanics and Geotechnical Engineering, A. Anagnostopoulos et al. (eds) IOS, Athens, 1: 369–374, doi:10.3233/978-1-60750-801-4-369
Morgenstern NR, Price VE (1965) The analysis of the stability of general slip surfaces. Geotechnique 15:79–93
Olivero S (1976) Executive design and report on geology and construction materials—Assino irrigation project. Unpublished report for Ente Autonomo per la Bonifica l’irrigazione e la valorizzazione fondiaria nelle Province di Arezzo, Perugia, Siena e Terni (in Italian)
Pánek T, Tábořík P, Klimeš J, Komárková V, Hradecký J, Šťastný M (2011) Deep-seated gravitational slope deformations in the highest parts of the Czech Flysch Carpathians: evolutionary model based on kinematic analysis, electrical imaging and trenching. Geomorphology 129:92–112
Pei J (2003) Effect of sample disturbance in Opalinus clay shales. MSc thesis, Massachusetts Institute of Technology, 213 pp
Pellegrino A (1966) Proprietà geotecniche dei terreni a grana grossa. Geotecnica 3:38–44 (in Italian)
Petkovšek A, Fazarinc R, Kočevar M, Maček M, Majes B, Mikoš M (2011) The Stogovce landslide in SW Slovenia triggered during the September 2010 extreme rainfall event. Landslides 8:499–506
Petley DN, Mantovani F, Bulmer MH, Zannoni A (2005) The use of surface monitoring data for the interpretation of landslide movement patterns. Geomorphology 66:133–147
Rulon JJ, Rodway R, Freeze A (1985) The development of multiple seepage faces on layered slopes. Water Resour Res 21(11):1625–1636
Servizio Geologico d’Italia (1968) Geological map of Italy scale 1:100000, sheet 131—Foligno. Poligrafico dello Stato
Skempton AW, Leadbeater AD, Chandler RJ (1989) The Mam Tor landslide, North Derbyshire. Phil Trans R Soc Lond A 329:503–547
Squeglia N, Pallara O, Mensi E (2006) Caratterizzazione meccanica dei depositi di terreni mediante prove penetrometriche dinamiche. Incontro Annuale dei Ricercatori di Geotecnica, Pisa, 4 pp (in Italian)
Stark TD, Vettel JJ (1992) Bromhead ring shear test procedure. Geotech Test J 15(1):24–32
Urciuoli G (1994) Caratterizzazione meccanica dei corpi di frana in terreni argillosi. In: Pellegrino A. (ed) Interventi di stabilizzazione dei pendii, International Centre for Mechanical Sciences, 65–98 (in Italian)
Acknowledgments
The research was conducted thanks to a sponsored contract from Alta Scuola (Master School and Institute for Studies on Maintenance and Conservation of Historical Centres in Unstable Territories). Studies and investigations were implemented and coordinated by Spoleto Municipality, with special mention of the Technical Office, run by Massimo Coccetta. The authors wish to thank Beniamino D’Elia (formerly professor of Geotechnical Engineering, Dept. of Structural and Geotechnical Engineering, Sapienza University), head of the contract, whose comments, suggestions and continuous discussion on data interpretation and analysis of instability mechanisms greatly improved the original manuscript. The authors acknowledge the assistance of Claudio Soccodato (Alta Scuola) in solving logistical problems throughout the study and of Riccardo Cardinali (Spoleto Municipality) in overcoming the countless difficulties in planning and running investigations. Special thanks to Maurizio Sciotti (formerly professor of Engineering Geology, Dept. of Civil and Environmental Engineering, Sapienza University) for the reappraisal of core logging, interpretation of aerial photographs and the many fruitful discussions on the slope evolution. Valle Umbria Servizi (V.U.S.), Spoleto, provided data on flow rates at the Montemartano spring.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Grana, V., Tommasi, P. A deep-seated slow movement controlled by structural setting in marly formations of Central Italy. Landslides 11, 195–212 (2014). https://doi.org/10.1007/s10346-013-0384-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10346-013-0384-6