Observation and modeling of the seismic seiches triggered in the Gulf of Corinth (Greece) by the 2011 M w 9.0 Tohoku earthquake

International audience; The study reports an unusual water level rise in the Gulf of Corinth, central Greece, during the passing of theseismic waves of the remote 2011 Mw 9.0 Tohoku earthquake. The seismic seiches were recorded by a tide-gaugelocated in the marina of the island of Trizonia, in the western side of the gulf. The cross-analysis between theground motion and the water level changes shows that seiching was initiated by the arrival of the earlier S-wavesand then enhanced by the surface waves. The seiching concerns five domains with periods ranging from minuteto about 7 min and with water level changes of a few millimeters to a few centimeters. The main seiching periodis about 5–7 min and the related water level has a maximum trough-to-peak amplitude of about 6–8 cm.Numerical simulation of the seismic seiches, based on the shallow water equations, allows us to model reasonablywell the amplitude of the seiches for most of the period domains, excepted those for the main seichingperiod at 7 min, which are underestimated by a factor of about 2–3. The largest bathymetric structures of thegulf to be excited in a seiche mode, with eigenperiods of hundreds of seconds, are a few kilometers in size.