Proceedings of the Second World Landslide Forum – 3-7 October 2011, Rome Andrea Manconi (1) , Paolo Allasia (1) , Daniele Giordan (1)* , Marco Baldo (1) , Giorgio Lollino (1) , Angelo Corazza (2) and Vincenzo Albanese (2) Landslide 3D surface deformation model obtained via RTS measurements (1) CNR-IRPI, Gruppo di Geo-Monitoraggio, Strada delle Cacce 73, 10135, Torino, Italy, *corresponding author: daniele.giordan@irpi.cnr.it , Tel: +39 0113977829. (2) Dipartimento della Protezione Civile, Rischi Idrogeologici e Antropici, Roma, Italy. Abstract. We present a new procedure that allows retrieving in near-real-time 3D surface deformation models starting from data acquired via Robotized Total Stations (RTS). The RTS measurements are first pre-processed and then implemented on 3D maps that include vector arrows representative of the intensities and of the real directions of motion in a given system of coordinates. The 3D surface deformation models are finally overlain on a DTM and/or on an updated picture of the monitored area. We discuss an example of application to an active large-scale landslide located in the area of Montaguto (southern Italy, ca. 100 km northeast from Naples). In this complex landslide scenario, the use of 3D representations of the surface deformation simplified the understanding of the evolution of the landslide phenomenon and received positive feedbacks from operators of the Italian Civil Protection Department. Keywords Near-real-time landslide monitoring, Surface deformation, Robotized Total Stations. 1. Introduction The identification and interpretation of surface displacements plays an important role in many landslide scenarios (Liu et al., 2004; Rizzo & Leggeri, 2004). In these contexts, the use of Robotized Total Stations (RTS) is frequently preferred due to its relatively simple installation, its straightforward operational use and data processing modalities, as well as its limited costs compared with new- generation instruments employed for topographic surveys. By using RTS is possible to retrieve changes of the x, y and z coordinates of a set of targets (usually optical prisms) with sub-centimetre accuracies. Moreover, depending on the number of prisms installed and on the availability of power supply, RTS may allow following the temporal evolution of the surface displacements of a landslide in near-real-time. In RTS surveys, measurements occur at the point targets only, thus the spatial representation of surface displacements is intrinsically limited. In order to overcome this limitation, especially when the landslide phenomenon presents complex spatial heterogeneities (e.g. areas with different directions and velocities of motion), it is envisaged an accurate planning of the network and an increase of the prisms number installed in the monitored area. Depending on the complexity of the phenomenon, the understanding of its kinematic with the classical visualization of RTS displacement time series might be very difficult (see example in Figure 2b-c). In addition, since the surface displacement monitoring is frequently aimed also at guaranteeing safety conditions of people and/or infrastructures, many operators of different scientific and technical backgrounds collaborate. Therefore, a straightforward and clear representation of the surface displacement evolution in near-real-time is necessary in order to support authorities and decision makers. In this work, we present a procedure that allows retrieving in near-real-time three-dimensional models of the surface displacements by using RTS measurements. After the acquisition step, the measurements are opportunely pre- processed and then implemented in 3D surface deformation maps, including also vector arrows representative of their intensity and direction of motion. The procedure may consider different interpolation algorithms and includes also the possibility to take into account as input a set of constraints, which may involve geological and/or structural discontinuities. In the following, we first describe the procedure and then we present the results of a real application to a large-scale landslide located in the area of Montaguto (southern Italy, ca. 100 km northeast from Naples).