Significant earthquakes of 368

October 11, 368 Earthquake: Nicaea [iznik], Turkey

October 11, 368

An earthquake struck Nicaea [iznik], Turkey on October 11, 368. It caused a tsunami.

Map

Where it struck, with the other significant earthquakes within 200 km. Circles are sized and colored by magnitude; select one for its page.

The earthquake

Date
October 11, 368
Place
Nicaea [iznik], Turkey
Epicenter
40.000° N, 29.000° E
Country
Turkey

The toll

Damage
Severe (about $5 to $25 million)

Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.

What the record says

NCEI’s account, from the sources it cites.

368, October 11. An earthquake destroyed Nikea, somewhat later another earthquake caused destruction in Hellespontus. (reference #1149)

368, October 11. An earthquake in Nicaea. A little after October 11, 368, the Hellespont. (reference #521)

368 Oct 11. An earthquake in Bithynia destroyed Nicaea (lznik) and ruined other towns in that province. The shock does not seem to have affected any other large centre of population; possible location of the epicentral area would be Nicaea and further west in Bithynia. (reference #14000)

368, October 11, Nicaea. A rather large earthquake affected much of Bithynia, where it ruined Nicaea (lznik) and other unnamed towns in that province […] John of Nikiu claims that, when the earthquake happened in Nicaea, where the holy council had been held, 'the sea rose against if and overwhelmed it'. This detail is not known from other sources and it is probably a rhetorical exaggeration or resulted from conflating some of the effects of the earthquake of AD 365. He places the event 'in the days of ... Valens', so he may have syncretised it with the earthquake and tsunami of AD 365 (which did not affect Nicaea) (cf. Georgios Monachos. discussed in the previous entry). Nicaea is located about 30 km inland, on the shore of the shallow Lake Ascania, the size of which renders it unlikely to be capable of creating such a destructive wave. ldatius a near contemporary dates this event to 5th Ides Oct (11 October) during the second consulships of Valentinian and Valens = 11 October 368. Socrates Scholasticus, also a near contemporary, agrees with this date but erroneously adds that this 'was twelve years after the fall of Nicorriedea'. Sozomen, also a near contemporary, mentions a freak storm of giant hailstones “in many places ... and very great earthquakes overthrew other cities, especially Nicaea”. Saint Jerome, the Chronicle of Serl and the Chronicon Paschale date this event to 11 October 368, whereas Malalas gives September 368. Pseudo-Dionysius of Tell Mahre syncretises this event with the earthquake in Germe in November 368(?), as does Georgios Monachos. Guidaboni et al. (1994, 274-275) include in the description of this event data from sources such as Eli. Nis. BR 102 and DE 23 that in fact refer to the earthquake in Nicomedea of 28 Ab 669 a.S. (August 28 358) and also associate the event with a seismic sea wave. (reference #9116)

Other significant earthquakes nearby

Within 200 km, the deadliest first.

More

Significant earthquakes of 368The 300sRecent earthquakes near hereThis day in weather history

Sources

Significant earthquakes from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. NCEI earthquake 99.