San Leo: Centuries of Coexistence with Landslides

Benedetti, G.; Bernardi, Matteo; Bonaga, Gilberto; Borgatti, Lisa; Continelli, Francesca; Ghirotti, Monica; Guerra, Cristiano; Landuzzi, Alberto; Lucente, C. C.; Marchi, Gianfranco

doi:10.1007/978-3-642-31319-6_69

Cited by 13 publications

(11 citation statements)

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“…Many historical documents, such as chronicles, letters, paintings and, more recently, vintage photos, witness the history of San Leo coexistence with landslide hazards (Benedetti et al 2011).…”

Section: Past Landslidesmentioning

confidence: 99%

The 27 February 2014 San Leo landslide (northern Italy)

et al. 2015

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The report describes a recent landslide occurred in San Leo (northern Italy), an outstanding village from the historical, architectural and landscape point of view. On February 27, 2014, around 6 pm local time, about 0.30 Mm3 of rock detached from a sub-vertical cliff and fell into the facing valley, producing a roar and a shake, which was initially perceived by the inhabitants as an earthquake, then followed by a dust cloud produced by the fragmentation of material during the collapse. Fortunately, nobody was injured, neither the landslide damaged any relevant structure; anyhow, it is still posing a severe threat to the village and, above all, to the fortress that represents an architectural masterpiece dating back to the middle ages. An outlook of the event will be given, along with the description of the peculiar geological and geomorphological features driving the slope instability phenomena, which indeed are widely diffused in the entire region. Lastly, an overview of the landslides, which historically affected the village, is also given, showing how natural hazards can influence the history of a site

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Section: Past Landslidesmentioning

confidence: 99%

The 27 February 2014 San Leo landslide (northern Italy)

et al. 2015

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“…Analysing the phenomena at the cliff-scale, although the lateral spread can definitely influence the acting processes, the undermining at the toe of the cliff seems to play a key-role in ultimate failure developing. Slope instability processes affecting the San Leo rock slab are apparent in ancient photographs, drawings and writings covering the last 4 centuries (Benedetti et al 2013). In the last decade, two large-scale failures have occurred.…”

Section: Typical Slope Instability Phenomenamentioning

confidence: 99%

Back Analysis of the 2014 San Leo Landslide Using Combined Terrestrial Laser Scanning and 3D Distinct Element Modelling

et al. 2015

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Landslides of the lateral spreading type, involving brittle geological units overlying ductile terrains, are a common occurrence in the sandstone and limestone plateaux of the northern Apennines of Italy. The edges of these plateaux are often the location of rapid landslide phenomena, such as rock slides, rock falls and topples. In this paper we present a back-analysis of a recent landslide (February 2014), involving the north-eastern sector of the San Leo rock slab (northern Apennines, Emilia-Romagna Region) which is a representative example of this type of phenomena. The aquifer hosted in the fractured slab, due to its relatively higher secondary permeability in comparison to the lower clayey units leads to the development of perennial and ephemeral springs at the contact between the two units. The related piping erosion phenomena, together with slope processes in the clayshales have led to the progressive undermining of the slab, eventually predisposing large-scale landslides. Stability analyses were conducted coupling Terrestrial Laser Scanning (TLS) and Distinct Element Methods (DEMs). TLS point clouds were analyzed to determine the pre-and post-failure geometry, the extension of the detachment area and the joint network characteristics. The block dimensions in the landslide deposit were mapped and used to infer the spacing of the discontinuities for insertion into the numerical model. Threedimensional distinct element simulations were conducted, with and without undermining of the rock slab. The analyses allowed an assessment of the role of the undermining, together with the presence of an almost vertical joint set, striking sub-parallel to the cliff orientation, on the development of the slope instability processes. Based on the TLS and on the numerical simulation results, an interpretation of the landslide mechanism is proposed.

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“…The 2014 failure occurred along the north-eastern corner of the plateau. Previously, another large landslide occurred in 2006 along the northern side [51]. Additionally, the gentle slopes formed by the Argille Varicolori formation are affected by earth flows, earth slides, and soil creep.…”

Section: Geological Overview Of the Areamentioning

confidence: 99%

A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

et al. 2019

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The stability of high rock slopes is largely controlled by the location and orientation of geological features, such as faults, folds, joints, and bedding planes, which can induce structurally controlled slope instability. Under certain conditions, slope kinematics may vary with time, as propagation of existing fractures due to brittle failure may allow development of fully persistent release surfaces. In this paper, the progressive accumulation of brittle damage that occurred prior to and during the 2014 San Leo landslide (northern Italy) is investigated using a synthetic rock mass (SRM) approach. Mapping of brittle fractures, rock bridge failures, and major structures is undertaken using terrestrial laser scanning, photogrammetry, and high-resolution photography. Numerical analyses are conducted to investigate the role of intact rock fracturing on the evolution of kinematic freedom using the two-dimensional Finite-discrete element method (FDEM) code Elfen, and the three-dimensional lattice-spring scheme code Slope Model. Numerical analyses show that the gradual erosion of clay-rich material below the base of the plateau drives the brittle propagation of fractures within the rock mass, until a fully persistent, subvertical rupture surface form, causing toppling of fault-bounded rock columns. This study clearly highlights the potential role of intact rock fracturing on the slope kinematics, and the interaction between intact rock strength, structural geology, and slope morphology.provide kinematic release to blocks that were previously nonremovable [9]. The accumulation of brittle damage is a critical component in the development of footwall failures and large-scale, biplanar, and compound rockslides, due to the formation of a highly damaged transition zone at the interface between active and passive blocks [10][11][12]. Additionally, intact rock fracturing may cause the failure of nondaylighting rock wedges, due to the formation of a basal rupture surface caused by failure of rock bridges and coalescence of brittle cracks [13].The strength of intact rock is orders of magnitude higher than discontinuities; therefore, strength and size of intact rock bridges between discontinuities have a great impact on the stability of rock slopes [9]. A small amount (0.1-10%) of rock bridges favorably distributed within a rock slope strongly increases the stability of the slope [14,15]. Despite the major significance of intact rock bridges in controlling the behavior of rock masses, their characterization remains an extremely challenging task [14], and the deterministic quantification of the rock bridges existing along a rupture surface may be undertaken only after failure occurs [15][16][17]. Discrete fracture networks (DFNs) are consequently being increasingly employed in rock engineering to investigate the distribution and dimensions of rock bridges using a stochastic approach [18].In this paper, the effects of intact rock fracturing on the evolution of the kinematic freedom of rock slopes are investigated using the 2014 San...

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San Leo: Centuries of Coexistence with Landslides

Cited by 13 publications

References 1 publication

The 27 February 2014 San Leo landslide (northern Italy)

The 27 February 2014 San Leo landslide (northern Italy)

Back Analysis of the 2014 San Leo Landslide Using Combined Terrestrial Laser Scanning and 3D Distinct Element Modelling

A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

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