April 24, 1928 Tsunami: Aegean Sea, Greece

1928, April 24, 01:15 UTC. 38 N, 23.5 E, magnitude 5, Aegean Sea. Unusual movements of the sea were observed between the morning of April 24 and the morning of April 25 near the shores of Greece and on islands from the northern coast of the Island of Crete up to the Island of Limos. Irregular quick rises and drops of the sea level were noted near the embankment of the port in Piraeus at 09h. Their period was approximately 10 min between 15" and 16h30" and at about 20h. The level rose up to 0.5 m (2 feet). In addition, noticeable flows were observed in front of the port and near its entrance. The 25 cm drop in the sea level was observed on the Island of Andros at 1Oh; suddenly, the level assumed its usual position after 1.5 hours. A sudden 40 - 50 cm rise in the sea level was observed on the Island of Syros at approximately 09h30m, a drop of approximately 20cm lower than the usual level followed after 5 min.

A rise and fall of sea level almost the same as on April 22 were observed in Karistos during the whole day, especially between 12h and 23h. Currents changed direction every 5 minutes; the sea would rapidly flow into the port and then recede, its level falling by 30 cm. A sudden rise over 0.5 m in the sea level was observed in Chalkida near the port and in the northern port at approximately 1l hth;is lasted about 15 min. The sea level was observed to rise a little relative to its usual position at 2zh together with an unprecedentedy rapid flow.

At approximately 10h, the sea receded from the coast of the Island of Mykonos in many places, especially near the village of Mykonos, where the sea receded for a distance of 15 - 20 m. At the same time, a similar phenomenon occurred in the port of Mykotios, where the water receded approximately for 10 m. The water rose by 0.5 m on the Zslatid of Milos within the entire bay of the same name.

Workers in the port of Heruckon claimed that the sea level rose by 1 my other witnesses observed an insignificant rise in the level. Fishermen in a small

boat 6 km to the east of Heracleon noticed a 0.5 m drop of the sea level, and the crew of a sailing vessel sailing 20 km to the west of the town noticed a similar rise of the level at about 12h. According to an engineer of the port of Heracleon, the sea surface at first rose and subsided rapidly; the amplitude of these oscillations increased gradually. A strong wave 2m high rolled up onto the

coast at approximately 14h; the water covered the parapet of the pier. An offshore current followed immediately after the wave with such a force that the fishing boats near the port were carried out into the open sea. Then the currents

weakened gradually and ceased altogether by 07h on the following day, i.e. on April 25. According to a report of the director of the weather bureau in Heracleon, the sea currents had a velocity of about 6 knots.

The water receded from the coast by approximately 1.5 m as a result of a lowering of the sea level in Nafplio at 14'30m. The reverse flow appeared several minutes later, and the normal level was exceeded by 0.5 m. Then, the water receded again, and the level returned into its usual position. According to accounts, a similar phenomenon took place on the shore of Tolo, 12 km from Nafplio.

Judging from the onset time of the tsunami in various places, the source of waves more or less coincided with the focus of the main earthquake on April 22 and with its aftershock on April 24, the data on which were given above. But the waves, apparently, began 5 hours after the shock. It can therefore be assumed that they were caused by a powerful underwater landslide. (reference #2130)