Joint electrical and time domain electromagnetism (TDEM) data inversion applied to the super sauze earthflow (France)

In order to evaluate the risk of an earthflow to evolve abruptly into torre ntial surge, knowledge of its internal structure is necessary. This study d eals with the internal structure of the Super Sauze earthflow developed in black marls in the southern French Alps. Difficulties in this study area ar e a rough topography, surface heterogeneities and a large thickness variabi lity of the earthflow mass. These conditions hamper the application of geot echnical methods as a preferred investigation mean. Moreover, they pose pro blems to geophysical investigations and their interpretation. This paper shows the advantage offered by the joint inversion of Time Domai n ElectroMagne-tism data (TDEM) and data obtained from Direct Current sound ings (DC). The results of the joint inversions are checked using geotechnic al data. The internal structure of the earthflow interpreted on the basis o f joint inversion data is comparable to that obtained from geotechnical res ults. Moreover, contrary to separate electrical and TDEM inversions, a sati sfactory joint inversion model can be derived without supplying additional a priori information.