The 1956 Amorgos earthquake, with a magnitude of 7.7, was the largest Aegean earthquake in the 20th century, and triggered a tsunami with local run-ups exceeding 20 m. This earthquake occurred along the Santorini-Amorgos area, where extension and volcanism are closely linked, and associated with prior major eruptions (e.g., ~1600 BC at Santorini , or ~1650 AD at Kolumbo).  The position of the epicentre is poorly constrained, and the proposed hypocenter depths vary between ~40 and 15 km. Additional constraints are thus required to better understand the location and geometry of seismogenic zones, identify the reactivated fault, and better inform seismic hazard analyses.

The objective of the AMORGOS-22 cruise was to carry out high-resolution bathymetric surveys with the IdefX AUV, in order to image submarine fault scarps to better characterise them, identify landslides along the Santorini-Amorgos fault system and establish their relationships and possible interactions. These were used as a benchmark for bottom geological observations and sediment sampling with the Ariane HROV during the AMORGOS-23 cruise. The new data will be used to discuss the different scenarios proposed for this earthquake and to better constrain the source of the tsunami (seabed rupture or landslide).

In total, 7 dives were carried out with the HROV, and a shallow bathymetric survey was possible thanks to Europe's ME70 echo sounder.