  | |
| Local date | 479 BC |
|---|---|
| Magnitude | 7.0 Ms |
| Epicenter | North Aegean Sea |
| Areas affected | Ancient Greece |
| Max. intensity | MMI IX (Violent) |
| Tsunami | Yes |
| Casualties | Many, possibly at least hundreds of fatalities |
The 479 BC Potidaea tsunami is the oldest record of a paleotsunami in human history. [1] The tsunami is believed to have been triggered by a Ms 7.0 earthquake in the north Aegean Sea. The associated tsunami may have saved the colony of Potidaea from an invasion by Persians from the Achaemenid Empire.
The Aegean Sea is a seismically active region with complex plate tectonics interaction both within and surrounding the Aegean Sea plate. Seismicity in the Aegean Sea is due to active extension within the lithospheric plate.
The Aegean Sea plate is defined along several major plate boundaries including the North Anatolian Fault which runs through northern Turkey, where the Anatolian Plate slides past the Eurasian plate along this right-lateral strike-slip fault. The southern margin is dominated by active convergence of the African plate. It converges north towards the Aegean Sea plate at a rate of 5–10 mm/yr. The subduction rate along the Hellenic subduction zone at 35 mm/yr, however, greatly exceeds the velocity of the African plate. North–south extension within the Aegean Sea plate in the back-arc region compensates the subduction rate. Shallow crustal earthquakes within the Aegean Sea plate is a result of this extension, accommodated by east–west trending normal faults. [2]
The Ms 7.0 earthquake had an epicenter somewhere in Macedonia. It was given a maximum Mercalli intensity of IX (Violent). [3]
During the Persian siege of the sea town Potidaea, Greece, Herodotus reports how Persian attackers who tried to exploit an unusual retreat of the water were suddenly surprised by "a great flood-tide, higher, as the people of the place say, than any one of the many that had been before". Herodotus attributes the cause of the sudden flood to the wrath of Poseidon. [4] The large tsunami was observed in the Toronean Gulf which devastated Potidaea. [5] The tsunami sank multiple Persian ships attempting to invade the colony, drowning several hundred soldiers. [6] [7] [8] The source of the tsunami is still controversial with its origins attributed to meteorological effects or a submarine landslide. Historical documents did not mention the occurrence of a storm however. [8]
The Anatolian sub-plate is a continental tectonic plate that is separated from the Eurasian plate and the Arabian plate by the North Anatolian Fault and the East Anatolian Fault respectively. Most of the country of Turkey is located on the Anatolian plate. Most significant earthquakes in the region have historically occurred along the northern fault, such as the 1939 Erzincan earthquake. The devastating 2023 Turkey–Syria earthquakes occurred along the active East Anatolian Fault at a strike-slip fault where the Arabian plate is sliding past the Anatolian plate horizontally.
The geology of Turkey is the product of a wide variety of tectonic processes that have shaped Anatolia over millions of years, a process which continues today as evidenced by frequent earthquakes and occasional volcanic eruptions.
The 1999 Athens earthquake occurred on September 7 at 14:56:51 local time near Mount Parnitha in Greece with a moment magnitude of 6.0 and a maximum Mercalli intensity of IX (Violent). The proximity to the Athens metropolitan area resulted in widespread structural damage, mainly to the nearby suburban towns of Ano Liosia, Acharnes, Fyli, Thrakomakedones, Kifissia, Metamorfosi, Kamatero and Nea Filadelfeia. More than 100 buildings across those areas collapsed trapping scores of victims under their rubble while dozens more were severely damaged. With damage estimated at $3–4.2 billion, 143 people were killed, and up to 1,600 were treated for injuries in Greece's deadliest natural disaster in almost half a century.
The Azores–Gibraltar Transform Fault (AGFZ), also called a fault zone and a fracture zone, is a major seismic zone in the Eastern Atlantic Ocean between the Azores and the Strait of Gibraltar. It is the product of the complex interaction between the African, Eurasian, and Iberian plates. The AGFZ produced these large-magnitude earthquakes and, consequently, a number of large tsunamis: 1755 Lisbon, 1761 Lisbon, 1816 North Atlantic, 1941 Gloria Fault earthquake, 1969 Horseshoe and 1975.
The Aegean Sea plate is a small tectonic plate located in the eastern Mediterranean Sea under southern Greece and western Turkey. Its southern edge is the Hellenic subduction zone south of Crete, where the African plate is being swept under the Aegean Sea plate. Its northern margin is a divergent boundary with the Eurasian plate.
The Hellenic Trench (HT) is an oceanic trough located in the forearc of the Hellenic Arc, an arcuate archipelago on the southern margin of the Aegean Sea Plate, or Aegean Plate, also called Aegea, the basement of the Aegean Sea. The HT begins in the Ionian Sea near the mouth of the Gulf of Corinth and curves to the south, following the margin of the Aegean Sea. It passes close to the south shore of Crete and ends near the island of Rhodes just offshore Anatolia.
The 1932 Ierissos earthquake occurred at 19:20 on 26 September. It caused severe damage in Ierissos, Greece and the surrounding part of the Chalkidiki peninsula, with 161–491 casualties reported.
The 1956 Amorgos earthquake occurred at 03:11 UTC on July 9. It had a magnitude of 7.7 on the moment magnitude scale and a maximum perceived intensity of IX on the Mercalli intensity scale. The epicentre was to the south of the island of Amorgos, the easternmost island of the Cyclades in the Aegean Sea. There was significant damage on Amorgos and the neighbouring island of Santorini. It was the largest earthquake in Greece in the 20th century. It was followed 13 minutes later by a magnitude 7.2 earthquake near Santorini. It triggered a major tsunami with a maximum run-up of 30 m. The combined effects of the earthquake shaking and the tsunami caused the deaths of 53 people with a further 100 injured.
On 21 July 2017, a large earthquake measuring 6.6 on the moment magnitude scale struck right near Bodrum, a popular town of tourism in Turkey, killing 2 and injuring hundreds. Mostly referenced as the 2017 Bodrum–Kos earthquake, this earthquake generated a tsunami which was one of the largest tsunamis in the Mediterranean Sea region.
An earthquake with a moment magnitude of 7.0 occurred on 30 October 2020 about 14 km (8.7 mi) northeast of the Greek island of Samos. Although Samos was closest to the epicentre, it was the Turkish city İzmir, 70 km (43 mi) northeast that was heavily affected—more than 700 residential and commercial structures were seriously damaged or destroyed. One hundred and seventeen people died in İzmir Province while an additional 1,034 were injured. In Greece, there were two fatalities and 19 injured. The earthquake is the deadliest in the year 2020, and the third major earthquake to strike Turkey that year. It generated an unusually large tsunami. The event is called the Samos earthquake by the International Seismological Centre.
The Hellenic subduction zone (HSZ) is the convergent boundary between the African Plate and the Aegean Sea Plate, where oceanic crust of the African is being subducted north–northeastwards beneath the Aegean. The southernmost and shallowest part of the zone is obscured beneath the deformed thick sedimentary sequence that forms the Mediterranean Ridge accretionary complex. It has a well-defined Wadati–Benioff zone of seismicity, which demonstrates the relatively shallow dip of its southern part, which increases markedly to the north of the non-volcanic part of the Hellenic arc. The descending slab has been imaged using seismic tomography down to the top of the mantle transition zone at 410 km depth.
The 1856 Heraklion earthquake, also known as the Crete earthquake or Rhodes earthquake, occurred on the morning of October 12 at 02:45 am local time. This extremely catastrophic earthquake had an estimated magnitude of 7.7 to 8.3 at a depth of approximately 61 to 100 km. The earthquake was felt over a very wide area extending from Sicily, Italy to the Levant and North Africa. On the Greek island of Crete, the effects of the earthquake were cataclysmic, over 500 bodies were recovered in the city of Heraklion. Shockwaves from the earthquake were felt intensely, covering all of the Ottoman Empire; present-day Turkey, Cyprus and the Middle East where damage and human losses were reported. In Malta, the Għajn Ħadid Tower—a coastal watchtower built around the year 1638—was severely damaged in the earthquake, when its upper floor collapsed. In Cairo, Egypt, the earthquake destroyed buildings, created seiches in canals, and killed several people. Off the Egyptian and Italian coasts, sailors reported feeling a seaquake.
The Nemuro-Oki earthquake in scientific literature, occurred on June 17 at 12:55 local time. It struck with an epicenter just off the Nemuro Peninsula in northern Hokkaidō, Japan. It measured 7.8–7.9 on the moment magnitude scale (Mw ), 8.1 on the tsunami magnitude scale (Mt ) and 7.4 on the Japan Meteorological Agency magnitude scale (MJMA ).
An earthquake occurred off the coast of the Alaska Peninsula on July 28, 2021, at 10:15 p.m. local time. The large megathrust earthquake had a moment magnitude of 8.2 according to the United States Geological Survey (USGS). A tsunami warning was issued by the National Oceanic and Atmospheric Administration (NOAA) but later cancelled. The mainshock was followed by a number of aftershocks, including three that were of magnitude 5.9, 6.1 and 6.9 respectively.
The 2021 Lasithi earthquake was a magnitude 6.4 Mw earthquake with a maximum intensity of VIII (Severe) on the Modified Mercalli Intensity Scale which occurred on 12 October 2021, 12:24 (UTC+3:30) off the island of Crete. The quake was also felt at low intensity as far as Cairo and Istanbul.
The 1815 Bali earthquake occurred on November 22 between 22:00 and 23:00 local time (WITA), affecting the Bali Kingdom. The estimated moment magnitude 7.0 earthquake struck off the north coast of Bali at a shallow depth. It was assigned a maximum intensity of IX (Violent) on the Mercalli intensity scale, causing severe damage in Buleleng and Tabanan. The earthquake caused a landslide and tsunami that killed 11,453 people.
The 1979 Yapen earthquake occurred on September 12 at 05:17:51 UTC. It had an epicenter near the coast of Yapen Island in Irian Jaya, Indonesia. Measuring 7.5 on the moment magnitude scale and having a depth of 20 km (12 mi), it caused severe damage on the island. At least 115 were killed due to shaking and a moderate tsunami.
The 1968 Aegean Sea earthquake was a Mw 7.0 earthquake that occurred in the early morning hours of February 20, 1968 local time about 57.1 km (35.5 mi) away from Myrina, Greece. This earthquake occurred between mainland Greece and Turkey, meaning both countries were impacted. 20 people died, and 39 people were injured to various degrees. It was the deadliest Greek earthquake since the 1956 Amorgos earthquake.
The southern margin of the Gulf of Corinth was struck by a major earthquake on 26 December 1861 at 08:28 a.m. local time. It had an estimated magnitude in the range 6.6–6.7 Mw and a maximum felt intensity of IX (destructive) on the European macroseismic scale (EMS). It caused widespread damage on both sides of the Gulf and led to up to 20 deaths and a further 126 people being injured, 18 of them seriously. A series of tsunami waves were reported, with a maximum run-up of 2.1 m.
The 1933 Kos earthquake struck the Aegean Sea region on 23 April. It measured Mw 6.4 and had an epicenter offshore, near Kos, Greece. The earthquake collapsed many buildings on Kos, Nisyros and other islands. At least 181 people were killed with a possible death toll reaching several hundred.
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