July 9, 1956 Earthquake: Dodecanese, Greece

Aegean Sea, islands of Amorgos and Astypaiaia. A catastrophic earthquake occurred in Amorgos and was accompanied by tsunami. This earthquake was of the highest magnitude of the 20th century in Greece; it amounted to VIII-IX. 53 people were killed, 100 people were injured; 529 houses were destroyed completely and many houses were damaged.

The earthquake was accompanied by 400 aftershocks of magnitude Ms > 3.5. The focus of the earthquake stretching to the north - east was located in the comb - shaped Strait of Amorgos with maximum depth of 710 - 720 m that separates the Islands of Amorgos and Astypalaia. According to the calculations of the earthquake focal mechanism it occurred as the result of a pure strike-dip fault, oriented in a north - easterly direction.

On July 9, 1956 at 03:11:38 GMT a strong shallow earthquake occurred, with epicenter about 20 km south of the islands of Amorgos. This is considered as the strongest shallow earthquake occurred in Greece in this century. 53 people were killed, 100 injured. The main shock was followed 13 later by an aftershock of Ms=7.2 located about 5 km ENE of Santorini. This earthquake activity was associated with a very large tsunami 25 m height, observed in the southern coasts of Amorgos, and which affected all other central and southern Aegean islands and the northern coasts of Crete, where its heigh was 1-2 m. The tsunami source was located in the deepest part of the Strait of Amorgos. (reference #4139)

1956 July 09, 03:11:45.11 UTC. 36.664N 25.957E, magnitude 7.7 Mw, depth 20. (reference #10476)

53 deaths, 100 injured (reference #1250)

The earthquake caused serious damage to the islands of Santorini, Amorgos, Anafi, Astypalaea, Ios, Paros, Naxos, Kalymnos, Leros, Patmos, and Lipsi. A total of 529 houses were destroyed, 1,482 were seriously damaged and 1,750 were slightly damaged. The mainshock and the largest aftershock of M = 6.9 generated 13 min later caused 53 fatalities and 100 injured people. (reference #13873)

The main shock caused severe damage to the surrounding islands, subsequently enhanced by the twin shock, especially in Santorini. More than 3200 buildings were damaged, including ~500 that were completely destroyed; in addition, 54 people were killed in Santorini, and 100 people were injured […] Sixty-seven years after the 1956 Amorgos earthquake, we have used submarine vehicles to observe well-preserved and clearly visible traces of a large seafloor rupture along the Amorgos fault, allowing us to identify this as the likely source of the earthquake. (reference #14234)