In the face of rapid global change it is imperative to preserve geodiversity for the overall conservation of biodiversity. Geodiversity is important for understanding complex biogeochemical and physical processes and is directly and indirectly linked to biodiversity on all scales of ecosystem organization. Despite the great importance of geodiversity, there is a lack of suitable monitoring methods. Compared to conventional in-situ techniques, remote sensing (RS) techniques provide a pathway towards cost-effective, increasingly more available, comprehensive, and repeatable, as well as standardized monitoring of continuous geodiversity on the local to global scale. This paper gives an overview of the state-of-the-art approaches for monitoring soil characteristics and soil moisture with unmanned aerial vehicles (UAV) and air- and spaceborne remote sensing techniques. Initially, the definitions for geodiversity along with its five essential characteristics are provided, with an explanation for the latter. Then, the approaches of spectral traits (ST) and spectral trait variations (STV) to record geodiversity using RS are defined. LiDAR (light detection and ranging), thermal and microwave sensors, multispectral, and hyperspectral RS technologies to monitor soil characteristics and soil moisture are also presented. Furthermore, the paper discusses current and future satellite-borne sensors and missions as well as existing data products. Due to the prospects and limitations of the characteristics of different RS sensors, only specific geotraits and geodiversity characteristics can be recorded. The paper provides an overview of those geotraits.

International audienceThe 2002-2003 eruptive crisis of Stromboli volcano in the Aeolian Islands raised the question of how to assess the stability of the flanks of this volcanic edifice during such a crisis. To provide a response to this question, we analyzed a detailed fluid flow mapping plus the reiteration of a profile located in the vicinity of the active vents using the self-potential method, temperature data, soil-gas (CO2) measurements, and electric resistivity tomography. Coupling the interpretation of these methods that are sensitive to the flow of gas and water in the ground indicates the position of areas of mechanical weakness. In addition, they can be used to monitor the change in the discharge of fluids associated with these features before and during the 2002-2003 eruptive crisis. Our results emphasize the importance of old structural boundaries, such as the Large Fossa crater, in the development of the new set of fractures observed during the 2002-2003 eruptive crisis. Between October 2002 and January 2003, the use of CO2 soil-gas technique evidenced an increase in the discharge of CO2 outside the Large Fossa crater boundaries, along the failure boundary of the southern Sciara del Fuoco area. Self-potential and temperature measurements made before the 2002-2003 eruptive crisis reveal significant changes along the main structural boundaries of the Fossa area. The development of these anomalies is interpreted as an increase of the permeability of the structure from May 2000 to May 2002. Between January 2003 and March 2003 the reiteration of self-potential, temperature, and CO2 measurements shows an increase of fluid discharge along weakness planes located inside the Large Fossa crater boundary. They evidence no change outside this structural boundary. The importance of the Large Fossa crater boundary in controlling the deformation and fluid flow from January to March 2003 has been attested by the development of the fractures inside the Large Fossa crater boundary, and also with a network of electrooptical distance measurement stations located inside and outside this ancient crater. This multidisciplinary approach to fluid flow assessment before and during an eruptive crisis is complementary to geodetic measurements of the deformation of the edifice. It demonstrates for the first time the powerful potential of combining electrical resistivity tomography, self-potential, temperature, and soil CO2 measurements in assessing the position of the planes of mechanical weakness in a volcanic edifice

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