September 25, 478 Tsunami: Marmara Sea, Turkey
A tsunami caused by a magnitude 7.2 earthquake began at Marmara Sea, Turkey on September 25, 478.
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
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
- September 25, 478
- Source
- Marmara Sea, Turkey
- Cause
- Earthquake
- Earthquake
- Magnitude 7.2
- Runups recorded
- 0
- Waters
- Ocean
- How certain
- Probable tsunami
- Source location
- 40.800° N, 29.200° E
The toll
- Deaths
- Many (about 101 to 1,000) with the earthquake or eruption that caused it
- Damage
- Limited (under about $1 million); Moderate (about $1 to $5 million) with the earthquake or eruption that caused it
- Houses destroyed
- Few (about 1 to 50); Some (about 51 to 100) 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.
478, September 25. Marmara Sea, 40o48'N, 29o12'E, earthquake magnitude 7.2, intensity IX, tsunami reliability 3. Damaging wave in Constantinople. (reference #2427)
478, September 25. The earthquake was followed by a damaging seawave and by aftershocks that continued for 40 days. The emperor fled the capital and took refuge in Chalcedon(Kadikoy). The shock caused damage in Thrace and in Bithynia and the towns destroyed received.financial assistance from the imperial treasury for reconstruction. (reference #14000)
478, September 25. In Istanbul the sea became very wild, rushed right in, engulfed a part of what had formerly been land, and destroyed several houses (reference #9275)
There must have been some damage in Nicaea, where, a later source says, the sea (lake), rose up against the town and overwhelmed it, a rather exaggerated statement that must refer to the Sea of Marmara. There the earthquake was followed by a sea wave, which flooded the coast, in places that are not named, destroying several houses […] The Great Chronographer places this event during the reign of Zeno (AD 474-491) after the Rhodes earthquake, mentioning a sea wave, long-lasting aftershocks and damage outside the city. As was noted under the previous entry, he may have had access to early records. (reference #9116)
Reference #11164 (v.2) lists as definite tsunami
More
Every tsunami in 478The 400sTsunamis 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 2317.