2. Methodological approach

2.1 Targeting probable active faults

Considering the dimension of the Upper Rhine Graben, it has been decided that the study will extend essentially to the french territory. The aim of the methodological approach is to focus from large scale area using morphological analysis to lower scale zones using complementary methods (morphological, geophysical and field investigations)

The"classical geology" approach to study the URG is well known, thanks to petroleum and salt exploration and exploitation. Quaternary geology has been mainly studied with a geomorphological and sedimentological approach. Only a few studies have considered quaternary tectonics. The methodology used for this study consist in an approach based on morphological identification of presumed faults scarp deduced from aerial photographs analysis, Digital Elevation models and Spot images analysis. This combined analysis allowed us to focus on specific interesting regional morphological expressions. The first stage of this work focused on the inner graben where quaternary sediments do exist and allow dating. It is clear that a great part of the Vosges borders are the expression of active faulting, but the lack of quaternary deposits and the possibility of fault exhumation by erosion are not favorable for the purpose of this studies. A second phase of this work will consider the border regions.

In a second phase, every large scale target was investigated in the field in order to confirm or reject the morphological hypothesis.