Table 4 Overview of advantages/limitations of the employed methods with respect to landslide type and analysis context

Optical VHR (OOA)

Giampilieri

Shallow soil slides – Debris flows

Landslide mapping

i) great density of spatial information, ii) numerous platforms, iii) high spatial, temporal and spectral resolution, iv) OOA approaches able to delineate areas affected by landslides

i) high cost; ii) on-demand acquisition; iii) cloud cover; iv) acquisition limited to daylight, v) OOA thresholds definition between changed and unchanged areas

Spaceborne SAR (PSI)

Nebrodi e Peloritani

Complex, rotational and deep-seated landslides

Landslide detection and mapping

i) good cost/benefit ratio, ii) coverage of wide areas; iii) millimeter accuracy; iv) availability of historical archives (since 1992); v) day-night and all weather acquisition.

i) detection of fast movements; ii) monitoring in deferred time; iii) presence of dense vegetation cover; iv) geometric distortions; v) unusable to detect N-S oriented landslides.

UAV-DP

Ricasoli

Shallow landslides

Landslide characterization and mapping

i) Low cost, rapid survey; ii) high repeatability; iii) high resolution data; iv) avoidance of shadowing effects.

i) Restrictive UAV flight regulations; ii) skilled operator required; iii) negative effect of vegetation on the point cloud.

TLS - IRT

Elba island

Rock slides

Landslide risk scenario assessment

i) Favorable logistic conditions (up-close survey); ii) Rapid 3D surface, geo-structural and geo-mechanical survey; iii) detailed unstable masses detection-volume calculation.

TLS: i) point cloud resolution related to scenario distance; ii) negative effect of vegetation on the point cloud. IRT: iii) scenario thermal contrasts related to slope orientation-roughness and solar radiation (daily/seasonal variations).

GB-InSAR - TLS - IRT

San Leo

Rock fall

Landslide long-term monitoring

i) Multi-system approach for wide range of instability process detection and analysis; GB-InSAR: ii) millimeter accuracy; iii) continuous monitoring. iv) day-night and all weather acquisition.

i) Intrinsic limitation of each adopted technique (L.O.S, range of detectable velocity, repetition time). IRT-TLS: ii) only periodical check. GB-InSAR: iii) uncapability for detecting rapid and perpendicular displacements with respect to the L.O.S.; iv) ambiguity in locating displacements for overhanging- slope sectors.

GB-InSAR

Santa Trada

Translational slide

Landslide Emergency management

i) Rapid installation; ii) day-night and all weather acquisition; iii) early warning and rapid assessment of risk scenario.

i) System loss of coherence, spatial and temporal decorrelation due to vegetation cover; ii) not favorable alignment between system L.O.S. and landslide movement direction (only 15–35% of displacement detected).