A large pleasure boat or an underwater rock slide were yesterday blamed for waves up to two meters high hitting beaches in the Gulf of Corinth, injuring four bathers and startling dozens of others. The waves hit the beaches of Kiato, Derveni, Selianitika and Loggos last week, prompting fears there had been an earthquake. Officials were yesterday considering two different possibilities. The head of the Civil Protection Authority in Achaia, Dimitris Filippatos, said yesterday the sea was up to 980 meters deep in some areas of the gulf and that it was possible there had been an underwater rock slide. Giorgos Ferentinos, a geology professor at the University of Patras, discounted this explanation. «It could not have been an underwater rock slide as no waves were recorded on the opposite shores.» He said that it was more likely a large vessel had caused the waves.