Update 2018-10-26: According to first reports, the strong earthquake south-west of the island of Zakynthos caused power blackouts early Friday morning (26 October, local time). Landslides were also triggered on the western Greek island. Major damage and casualties were not initially reported. Casualties, however, cannot be ruled out.
Aftershocks, which may cause additional damage, are possible in the region. Travellers are advised to inform themselves via local media and authorities about the current situation on site, to follow instructions from authorities, to exercise high caution near mountainsides and rivers, as well as to avoid damaged buildings, bridges, and roads.
2018-10-25, Greece: Strong magnitude 6.8 M coastal earthquake
Earthquakes of this magnitude cause damage (sometimes severe), to buildings and infrastructure. Transport and infrastructure disruptions are to be expected.
It is unlikely that a destructive tsunami was generated by a coastal earthquake of this magnitude. Smaller, local tsunamis can occur in coastal areas.