Distinction between seismic tsunamis and meteotsunamis recorded in Greece from antiquity up to the present

Abstract Tsunami generation from earthquakes is well-known in Greece from antiquity up to the present. Tsunami studies also include cases of tsunami-like sea disturbances that possibly were meteotsunamis because of their doubtful association with earthquakes. Descriptive information and tide-gauge records were examined for a set of ten cases, three of them occurring in historical times and seven during the instrumental period after 1900. Documentary sources supporting historical cases were examined as to their credibility and consistency. The cases examined have various patterns of sea oscillations, duration, geographical extent, and coincidence or non-coincidence with earthquakes. In general, they caused slight damage on some occasions, except for the 479 BCE ebb-flood in the NW Aegean Sea that reportedly drowned several people. Cases of instrumentally recorded long-period oscillations occurring in 1928, 1959, 1961, 1978, and 1991 had in common that they were recorded to spatial scales up to ~ 600 km. From tide-gauge records, empirical laws were produced for the amplitude attenuation of meteotsunamis and compared with the attenuation of seismic tsunamis in Greece. Discrimination between seismic tsunamis and meteotsunamis was based on the space–time coincidence with or without earthquake activity, on the possible excitation of sea oscillations from long-period seismic Rayleigh surface waves, on the rapid attenuation of seismic tsunamis as compared to meteotsunamis, on modes of oscillations, and on atmospheric disturbances. Discrimination criteria favor the meteorological origin of the tsunami-like cases examined, with the exception of a local seismic seiche that occurred after a strong earthquake in south Crete in 1979. A distinct case has been the sea oscillation recorded in the harbors of the north and south Aegean Seas and attributed to a mesoscale atmospheric disturbance moving from the Adriatic to the Aegean Sea. This episode concurred by coincidence with the strong earthquake (M w = 6.22) in the northern Greek mainland on 20 June 1978.