February 6, 1866 Tsunami: S. Coasts Peloponnesus, Greece

Name: February 6, 1866 Tsunami: S. Coasts Peloponnesus, Greece
Start: 1866-02-06
Location: S. Coasts Peloponnesus, Greece

February 6, 1866 · 8.6 m · Probable tsunami

A tsunami caused by a magnitude 6.8 earthquake began at S. Coasts Peloponnesus, Greece on February 6, 1866. The water rose as high as 8.6 meters. Its effects were recorded at 1 place.

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

Tsunami warnings in force

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: February 6, 1866
Source: S. Coasts Peloponnesus, Greece
Cause: Earthquake
Earthquake: Magnitude 6.8
Maximum water height: 8.6 m (28.2 ft)
Runups recorded: 1
Tsunami intensity (Soloviev-Imamura): 4
Waters: Ocean
How certain: Probable tsunami
Source location: 36.000° N, 23.000° E

The toll

Damage: Limited (under about $1 million); Severe (about $5 to $25 million) with the earthquake or eruption that caused it
Houses destroyed: Few (about 1 to 50)
Houses damaged: 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.

1866, February, 6. Peloponnesus' Marginal Islands (Cythera), 36N, 23E. A seismic sea wave set off by a severe shock on Cythera Island rose at Avlemonas (Viaradica) to heights of over 8m. (reference #109)

1866 February 6. South coasts of Peloponnesus. Island of Kythera (H = 7.30 m), (m = iv). (reference #28)

1866, February 6. Ionian Sea, Greece... In Avlemonas a tsunami wave was generated which reached a height of up to 8.6 m. (reference #2130)

1866 February 6. Tsunami intensity 4, Tsunami reliability 4 (definite). (reference #11164)

1866 February 6. The earthquake hit heavily Cythera and a sea wave of 8m high destroyed houses in Avlemona (Sieberg, 1932a). (reference #4408)

1866 February 6, Kithira. [...] there is no evidence whatsoever for a seismic sea wave. It is possible that there is some confusion with the earthquake of 20 September 1867. (reference #9116)

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
Avlemonas, Kythera Is, Peloponnesus	Greece	26	8.6		Eyewitness observation of water height

Every tsunami in 1866 The 1800s Tsunamis of Greece The earthquake This day in weather history Alerts 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 951.