A Review of the Advantages and Limitations of Geophysical Investigations in Landslide Studies

Abstract

Landslide deformations involve approximately all geological materials (natural rocks, soil, artificial fill, or combinations of these materials) and can occur and develop in a large variety of volumes and shapes. The characterization of the material inhomogeneities and their properties, the study of the deformation processes, and the delimitation of boundaries and potential slip surfaces are not simple goals. Since the ‘70s, the international community (mainly geophysicists and lower geologists and geological engineers) has begun to employ, together with other techniques, geophysical methods to characterize and monitor landslides. Both the associated advantages and limitations have been highlighted over the years, and some drawbacks are still open. This review is focused on works of the last twelve years (2007-2018), and the main goal is to analyse the geophysical community efforts toward overcoming the geophysical technique limitations highlighted in the 2007 geophysics and landslide review. To achieve this aim, contrary to previous reviews that analysed the advantages and limitations of each technique using a “technique approach,” the analysis was carried out using a “material landslide approach” on the basis of the more recent landslides classification.

Characterization and Geotechnical Investigations of a Riverbank Failure in Florence, Italy, UNESCO World Heritage Site

“…Geophysical Surveys (ERT, DH, and SN) Geophysical investigations are based on detecting changes in subsurface physical properties (e.g., electrical resistivity, seismic wave velocities, and density), and selecting a more suitable combination of methods is a trade-off between cost to time ratio, advantages (e.g., resolution, diagnostic capability, depth of investigation), and intrinsic limitations and ambiguities of each method (Pazzi et al 2019). The 3D-ERTs were performed (1) to locate the nineteenthcentury culvert, (2) to define the boundary between stable and unstable soil in the embankment, and (3) to characterize the soil on the side of the retaining wall both on the street and on the riverside.…”

Multiple Geophysical Techniques for Investigation and Monitoring of Sobradinho Landslide, Brazil

“…For geophysical site characterization, the traditional (ERT, GPR), as well as seismic based geophysical techniques (MASW and HVSR), are used. A detailed review of these techniques is available in the literature [3,51].…”

“…These methods can generally be classified into two categories: intrusive, which may involve boreholes, soil sampling and laboratory testing, and non-intrusive, namely geophysical methods. The deployment of the latter has been increased exponentially for the subsurface characterization, localization of sliding surface, evaluation of the emergence and growths of fractures as well as for the understanding of water dynamics and possible reactivation by rainfall [3]. The information obtained from geophysical surveys is used as an input for defining ground models of landslides and consequently to perform slope stability assessment [4].…”

“…After the in-situ soil testing [56], geophysical techniques (traditional as well as seismic based) were applied for the landslide site characterization. Each applied technique works on specific physical properties of the site such as electrical (ERT), electromagnetic (GPR) and elastic (seismic) [3].…”

Monitoring Soil Moisture Dynamics Using Electrical Resistivity Tomography under Homogeneous Field Conditions

“…A detailed overview of geophysical techniques for landslides studies is provided by [ 25 ]. ERT is described as a promising and useful technique to collect quantitative information within landslides, especially shallow landslides, on hydrological properties such as water content and water distribution and dynamics, and geotechnical parameters such as the failure plane can faults or cracks.…”