October 25, 989 Tsunami: Marmara Sea, Turkey
A tsunami caused by an earthquake began at Marmara Sea, Turkey on October 25, 989.
Where the waves reached
The source of the tsunami. No runup with a place is recorded for it.
- Under 1 m
- 1 to 3 m
- 3 to 10 m
- 10 to 30 m
- 30 m and more
- Height not recorded
The tsunami
- Date
- October 25, 989
- Source
- Marmara Sea, Turkey
- Cause
- Earthquake
- Earthquake
- The earthquake
- Runups recorded
- 0
- Waters
- Ocean
- How certain
- Very doubtful tsunami
- Source location
- 40.800° N, 28.700° E
The toll
- Deaths
- 1; Many (about 101 to 1,000) with the earthquake or eruption that caused it
- Damage
- Limited (under about $1 million); Severe (about $5 to $25 million) with the earthquake or eruption that caused it
- Houses destroyed
- Many (101 to 1,000) 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.
989 Oct 26. […] Waves flooded the coast and parts of Constantinople itself, with the sea advancing inland in places causing some additional damage, while offshore the waves destroyed the tower of Eutropius (Kiz Adasi) near the coast of Chalcedon, killing the monk who lived there. It is very likely that these waves were due to the heavy storms in the Sea of Marmara, which preceded and followed the event, rather than to the earthquake. (reference #9116)
989 Oct 25. The earthquake set up waves in the sea between the provinces of Thrace from Bythinia that reached into Istanbul. (reference #9275)
989 Oct 25. Very improbable tsunami (reference #11164, v.2)
More
Every tsunami in 989The 900sTsunamis 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 6013.