May 22, 1766 Tsunami: Marmara Sea, Turkey
A tsunami caused by a magnitude 6.5 earthquake began at Marmara Sea, Turkey on May 22, 1766 at 05:30 UTC. Its effects were recorded at 2 places. It killed 4,000 people, counting the earthquake or eruption that caused it.
Where the waves reached
The source (white) and every runup with a place, colored by the water height recorded there. A ring is a runup NCEI marks doubtful.
- Under 1 m
- 1 to 3 m
- 3 to 10 m
- 10 to 30 m
- 30 m and more
- Height not recorded
Travel times
How long the first wave took to reach each part of the ocean, one line for each hour up to 24, estimated from the source and the depth of the sea.
The travel times are computed in your browser, which needs JavaScript.
- 1 to 4 hours
- 5 to 6 hours
- 7 to 14 hours
- 15 hours and more
Computed in your browser the way NOAA’s own travel time maps are: the wave travels at the square root of gravity times the depth, over NOAA’s ETOPO1 depths averaged to a 10 arc-minute grid. Checked against NOAA NCEI’s maps for 21 tsunamis over the first 24 hours, these lines fall within 10 minutes of NCEI’s at half the points compared and within 52 minutes at 9 in 10. They give when the first wave could arrive, not how high it is; bays, harbors and island chains finer than the grid can see it later. Not for use in a warning: see tsunami.gov.
The tsunami
- Date
- May 22, 1766, 05:30 UTC
- Source
- Marmara Sea, Turkey
- Cause
- Earthquake
- Earthquake
- Magnitude 6.5
- Runups recorded
- 2
- Tsunami intensity (Soloviev-Imamura)
- 2
- Waters
- Ocean
- How certain
- Questionable tsunami
- Source location
- 40.800° N, 29.000° E
The toll
- Deaths
- 4,000 with the earthquake or eruption that caused it
- Damage
- Moderate (about $1 to $5 million); Extreme (about $25 million or more) with the earthquake or eruption that caused it
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.
Zone of the Sea of Marmara, Strait of Bosporus. An underground boom passed through Istanbul from the south to the north, after which strong ground shocks immediately followed in the same direction; they continued for 2 minutes without interruption. The town was destroyed. The sea was unusually turbulent. Underground shocks were often resumed during the day and then were felt till November. The boom was almost uninterrupted, especially on the sea shore. Lists event as a possible or questionable tsunami (reference #2130)
Strong earthquake affecting NW Turkey . At Costantinople tsunami intensity II attributed by Antonopoulos (r 417) who quotes the "Gazette de France, Paris (4 July 1766)" and the "Journal Historique, Paris". (reference #4139)
As a result of the earthquake Galata and the coast opposite Istanbul were flooded by the sea which submerged the quays and stripped them of their landing gear. The same phenomenon was observed along the Bosphorus, and further away along the coast at Mudanya where some villages were flooded. Uninhabited islets in the Marmara Sea were said to have half sunk into the sea. (reference #2955)
The earthquake was associated with a seismic sea-wave which was particularly strong along the Bosphorus, and in the Gulf of Mudanya where it caused considerable damage. (reference #14000)
Tsunami waves were recognized in the coastal village Besiktas-Istanbul and the inner parts of the Straits of Istanbul; uninhabited islets in the Sea of Marmara were said to have half-sunk into the sea. Izmit coasts were badly damaged by sea waves; strong waves were particularly effective along the Bosphorus and in the Gulf of Mudanya. Lists event as a definite tsunami (reference #9275)
Reference #11164 (v.2) lists event as a definite tsunami
Every runup
Nearest the source first. Heights are above sea level at the time; a tide gauge reads half the wave’s full height.
| Where | Country | Km from source | Water height, m | Inland, m | Measured by | First wave, UTC | Deaths |
|---|---|---|---|---|---|---|---|
| Istanbul (Constantinople) | Turkey | 24 | Eyewitness observation of water height | ||||
| Mudanya | Turkey | 51 | Eyewitness observation of water height |
More
Every tsunami in 1766The 1700sTsunamis of TurkeyThe earthquakeThis day in weather historyAlerts in force
Sources
Tsunami events and runups 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 tsunami event 2320.