Deformation of the ancient mole of Palairos (Western Greece) by faulting and liquefaction

A submerged 2300 years-old mole or breakwater with a sigmoidal shape has been identified at the Palairos harbor (Akarnania, SW Greece mainland). Different possible scenarios could be proposed to explain this enigmatic shape for an ancient breakwater, such as selective erosion of the original structure, construction above existing shoals or reefs, gravity sliding and post-construction offset due to strike-slip faulting, but all these scenarios seem rather weak. Inspired by a large scale lateral offset of a retaining wall of a quay at the Barcelona harbor due to static liquefaction, by evidence of strike-slip earthquakes and of liquefaction potential in the study area, as well as by recent evidence for long-duration steady, nearly uni-directional dynamic displacements in the near-field of strike-slip faults, we propose an alternative scenario for this mole. An earthquake associated with strike-slip faulting and high acceleration produced liquefaction of the mole foundations and long duration, nearly unidirectional tectonic slip, while the later part of the steady slip produced additional secondary (surficial) slip on liquefied layers.