Thiry et al (2025) Supplement #2-JASRep

The thick black crusts that cover the base of the annular structure in the LFO 1 shelter cavity in Courdimanche-sur-Essonne were interpreted as indicators of water arriving in the structure and a first flooding of the shelter was actually observed on August 10, 2021 (Thiry et al., 2021). Two questions were raised: (1) what was the periodicity of the seepages; and (2) how did the water infiltrate the shelter? These two aspects were investigated by first presenting a series of water seepages to estimate temporality of the efficient rain events and the second by carrying out tests to specify the infiltration conditions.