International audience; The north Ligurian margin is a complex geological area in many ways. It has witnessedseveral phases of highly contrasting deformation styles, at both crustal scale and that of shallower covertectonics, simultaneously or in quick succession, and with significant spatial variability. This complexinterplay is mirrored in the resulting intricate structures that make it hard to identify active faultsresponsible for both, the significant seismicity observed, and the tectonic inversion undergone bythe margin, identified at longer time scales on morphostructural grounds. We present here the firstpreliminary results of the leg 1 of SEFASILS cruise, conducted in 2018 offshore Monaco, in an effort toanswer these questions by means of modern deep seismic acquisitions, using multichannel reflectionand wide-angle sea-bottom records. Some first interpretations are provided and point towards anactive basement deformation that focuses at the limits between main crustal domains.