# Airborne Electromagnetics to Improve Landslide Knowledge in Tropical Volcanic Environments
## 6 Conclusions  
AEM data are powerful in revealing in-depth resistivity contrasts in a complex tropical environment [30]. Once the results are compared with in situ investigations, such as boreholes and field observations, it is possible to better delineate the different superimposed lithologies and to understand the internal structure of various grounds. This study illustrates an additional possibility to obtain reliable data on the first 50 m by this noninvasive geophysical method. The results are fundamental for landslide studies in these environments with complex accesses limiting the use of classical field investigation techniques. Thus, it would be essential to verify low-resistance bodies located at approximately 5 \(\Omega\).m between a depth of 10 and 50 m. The two examples of the La Medaille landslide and the Morne-Figure area show that under landslides, some low resistivity formations could play the role of aquifers concentrating underground flows, punctually recharging the upper layers and influencing the activity of slope instabilities. The study of these bodies over the whole island, in correlation with recent hydrological studies [12; 30] using AEM data, must be considered to better define this role on landslides [46]. It may be possible to refine the knowledge of unstable slopes from this information. From an operational point of view, the data acquired over the whole island could thus be exploited to (i) refine the knowledge of large landslides that regularly generate material damage and (ii) improve the spatialization of hazards and thus regulatory maps of landslide risks. Beyond the island of Martinique, the AEM method seems to be one of the most cost-effective methods to obtain geophysical information on shallow and deep formations, particularly in complex environments (topography, vegetation, and complex geological structure), such as the Caribbean. Thus, with the information acquired by this study and in [15], new perspectives to improve landslide hazard analysis and mapping for Martinique and other Caribbean islands can be considered. The following are available online at [[https://www.mdpi.com/article/10.3390/app11083390/s1](https://www.mdpi.com/article/10.3390/app11083390/s1)]([https://www.mdpi.com/article/10.3390/app11083390/s1](https://www.mdpi.com/article/10.3390/app11083390/s1)), Figure S1: EM profiles for the La Medaille landslide. Figure S2: EM profiles for Morne-Figure area. Figure S3: Concept of slope stability computations with a slice method. Conceptualization, Y.T. and P.-A.R. ; AEM data processing, P.-A.R. ; methodology, Y.T. ; software, Y.T. and P.-A.R. ; validation, Y.T. and A.N. ; formal analysis, Y.T. ; investigation, Y.T., P.-A.R. and A.N. ; writing--original draft preparation, Y.T., P.-A.R., A.N. ; writing--review and editing, Y.T. ; supervision, Y.T. ; project administration, Y.T. All authors have read and agreed to the published version of the manuscript. This research was supported by the Risk and Prevention General Direction of the French Ministry of Ecological Transition and the French Geological Survey (BRGM), contracts PS14 DRP041, PS15 DRP017 and AP16 DRP017. The heliborne geophysical survey, called \"MartEM\" program [53], was co-funded by BRGM, the FEDER funds for Martinique, the Regional Office for Environment Planning and Housing (DEAL), the Regional Council and the Water Office of Martinique (ODE). Not applicable.