Geophysical Study to the Port of Kos Island (Greece) after the Earthquake of 21st of July 2017

On 21st of July 2017 a 6.5-magnitude earthquake between Bodrum and Greek islands ( Fig. 1a ) strikes injuring more than 200 people. Kos’s port was put out of action due to damage at the harbor. Greek Authorities commissioned ISTRIA Ltd. and the Laboratory of Applied Geophysics of NTUA to conduct sampling drilling and geophysical research to provide the appropriate information to engineers for the port repair study. The initial design of the geophysical survey was for P and S refraction seismic survey in order to detect the depth to bedrock and identify the loose formations above through their seismic velocities. The actual field conditions resulting to hidden layer problems and noisy data have led to the use of MASW method exploiting the 5 shots and all the respective seismic data. The depth to bedrock was found well as borehole data indicated but details in the loose sediments above couldn’t be found with such a seismic array setup. ERT sections have shown the top of semi-impermeable zone to saline water and lateral inhomogeneities and GPR sections near surface loose sediment zones with higher presence of saline water and zones with regular presence possibly related with hidden anthropogenic structures.