Landslide risk evaluation requires accurate determination of geometrical limits of unstable bodies. Available tools to accomplish this goal include: remote sensing methods and detailed geological mapping on the surface, while subsurface information is obtained through the drilling of a limited number of boreholes, eventually equipped with measurement instrumentation (inclinometrs, tiltmeters, etc.). In the past few years the role of geophysical methods in the investigation of landslides has been increasing thanks to the most recent advancements in Hardware and software technology which allowed for gathering huge amounts of data (or measuring points) about the subsurface in a completely non-invasive and costeffective way. Among these methods we applied the electrical tomography (ET) technique to test its reliability to investigate and characterise shallow landslides in lithologically and/or structurally complex rock types, in an area located in the northern Apennines (Lizzano in Belvedere, 60 km SW Bologna, Italy). The method measures the distribution of the resistivity and/or polarizzability (method called induced polarization, IP) of the subsurface materials along profiles conducted on the earth surface permitting the subsurface to be imaged for both lateral and vertical variations. The acquisition of a large number of data at reasonable costs relative to others allows to define a 3D model of the subsurface. The electrical resistivity is a well-known physical property that is function of porosity, mineralogy and saturation. The chargeability (M) extends the resistivity method by making an additional measurement of the ability of the ground to store electrical charge as a result of an applied electric field.. However, many of these limitations have been overcome allowing the method to be used also in the field of environmental and engineering applications. Both properties (resistivity and chargeability) provide complementary information about the electrical properties of the subsurface geology. In this context, the aim of this work is to present a technique capable of mapping the subsurface lithologies in areas prone to landslides or areas to be assessed for landslide hazard estimation, that otherwise are difficult to acquire directly without drilling.
USE OF HIGH RESOLUTION 2D ELECTRICAL RESISTIVITY TOMOGRAPHY FOR LANDSLIDE INVESTIGATION
ABU-ZEID, Nasser;MAZZINI, Enrico;
2003
Abstract
Landslide risk evaluation requires accurate determination of geometrical limits of unstable bodies. Available tools to accomplish this goal include: remote sensing methods and detailed geological mapping on the surface, while subsurface information is obtained through the drilling of a limited number of boreholes, eventually equipped with measurement instrumentation (inclinometrs, tiltmeters, etc.). In the past few years the role of geophysical methods in the investigation of landslides has been increasing thanks to the most recent advancements in Hardware and software technology which allowed for gathering huge amounts of data (or measuring points) about the subsurface in a completely non-invasive and costeffective way. Among these methods we applied the electrical tomography (ET) technique to test its reliability to investigate and characterise shallow landslides in lithologically and/or structurally complex rock types, in an area located in the northern Apennines (Lizzano in Belvedere, 60 km SW Bologna, Italy). The method measures the distribution of the resistivity and/or polarizzability (method called induced polarization, IP) of the subsurface materials along profiles conducted on the earth surface permitting the subsurface to be imaged for both lateral and vertical variations. The acquisition of a large number of data at reasonable costs relative to others allows to define a 3D model of the subsurface. The electrical resistivity is a well-known physical property that is function of porosity, mineralogy and saturation. The chargeability (M) extends the resistivity method by making an additional measurement of the ability of the ground to store electrical charge as a result of an applied electric field.. However, many of these limitations have been overcome allowing the method to be used also in the field of environmental and engineering applications. Both properties (resistivity and chargeability) provide complementary information about the electrical properties of the subsurface geology. In this context, the aim of this work is to present a technique capable of mapping the subsurface lithologies in areas prone to landslides or areas to be assessed for landslide hazard estimation, that otherwise are difficult to acquire directly without drilling.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
