June 426 BC Earthquake: Euboea, Greece

426 B.C. Summer (possibly 425), 38.75 N, 22.75 E, earthquake magnitude 7.1, intensity XI, tsunami intensity v. Aegean Sea, eastern Greece. Island of Euboea, Gulf of Maliacus. Evidence provided by Thucidides indicates that a series of earthquakes occurred in the regions of Attica, Boeotia, Euboea in the autumn of 427 B.C. during the fifth year of the Petoponnesian war, which caused the Spartans, who interpreted underground shocks as a bad omen, to abandon attempts to conquest Attica although their forces had already reached the Isthmus of Corinth. Especially strong shocks occurred in Orchomenos. Earthquakes continued till the summer of 426 B.C. The shocks weakened by summer and autumn to an extent that the Spartans renewed their military operations, even in the focal zone of the earthquakes (in the region of Heraclea). Several shocks in the summer and autumn of 426 B.C. occurred in the strait separating the Euboea Island from the continent. The cities of Phalara (Stylis), Lamia, Larisa were completely destroyed as a result of a sole earthquake or a series of earthquakes. Terrible destruction took place in Heraclea. Skarfia, where 2,500 people were killed, suffered the same fate. The cities of Nope, Heraclea, Cynos, Opus, Echinos suffered serious damage. The fortress of Ohm towering above Opus was broken down. The wall of the city of Elatia came down in parts. In Alponous, towers and walls in the harbour crashed, dragging many inhabitants down with them into the water. The walls and 700 houses nearest to the coast tumbled down in Oreon on Euboea Island. The Orobies settlement (Rovies today) was also destroyed. Atalanti, Peparithos and Skopelos suffered damage, the walls of the city assembly hall and some houses were partly destroyed there.

As a result of the earthquake, the outflow of hot springs was interrupted at Aedepsos and Thermopyles for three days; they started flowing again later, but one of them in Aedepsos started gushing at a new place. Springs and rivers dried up everywhere for several days. The River Spercheios began to flow along a new course.

(above from reference #2130)

426 B.C. October, Maliac Gulf. A destructive earthquake in central Greece. According to Thucydides and Demosthenes it occurred during the celebration of the Thesmophotia (October/November) in the Athenian calendar), in the sixth year of the Peloponesian War (426 BC). Much of the destruction caused by the earthquake and the associated seismic sea wave occurred on both sides of the coasts of the Euboean, Maliac and Oreus Gulfs... Scarphea was flung up, foundations and all, with the loss of not less than 1700 men. At Thronium 850 people were killed and at Alponus the tower fell into the sea killing all in it. (reference #9116)

According to Demetrious of Gallatis (Strabo, liber i, cf. 3.20), much of the Lichades islands (Lichadonesia) and the promontory of Cenaeun (Kinaion) in northwestern Euboea were engulfed. A land strip that used to form a peninsula off the Greek mainland was tom through to form the Atalanta island (Talantonisi) (Diodoros, liber xii, cf. 58). In Euboea, the territory of Orobiae (Rovies) subsided and the shoreline advanced inland after the earthquake (Thucydides, liber iii, cf.89.2) (reference #544)

The intensity of the earthquake has been estimated as intensity XI (MSK scale) comparable to magnitudes between 6.9 (Papadopoulos et al. 2014) and 7.5 (Ambraseys 1997, Waldherr 1997). (reference #12668)