January 31, 1866 Tsunami: Thera Island (Santorini), Greece

Name: January 31, 1866 Tsunami: Thera Island (Santorini), Greece
Start: 1866-01-31
Location: Thera Island (Santorini), Greece

January 31, 1866 · 52 houses destroyed · Very doubtful tsunami

A tsunami caused by a volcano and a magnitude 6.1 earthquake began at Thera Island (Santorini), Greece on January 31, 1866. 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: January 31, 1866
Source: Thera Island (Santorini), Greece
Cause: Volcano and earthquake
Earthquake: Magnitude 6.1
Runups recorded: 1
Waters: Ocean
How certain: Very doubtful tsunami
Source location: 36.400° N, 25.300° E

The toll

Damage: Moderate (about $1 to $5 million) with the earthquake or eruption that caused it
Houses destroyed: 52 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, January 28 (31). Aegean Sea, Island of Thira. Eruption of the volcano of Santorini began and was accompanied, according to some data by tsunami. According to Perrey [1870], there was no tsunami. (reference #2130)

1866, January 31, night. 36.4 N, 25.4 E, magnitude 6.1, intensity VII, tsunami intensity 1, reliability 0. Sea disturbance. (reference #2427)

1866, January 31 (28), tsunami reliability 1-2. (reference #9275)

1866, January 31, night. Kyriazopoulos (1979) reports that by the strong eruption of the volcano of Nea Karnene the islet George and the ephemeral Afroessa were formed and he cites a poem of his family collection where it is written that the progressive subsidence of a part of the islet Nea Kamene started on 18 January. The sea started to blow up, the coastal houses to crack and to disappear under the water. The ship masters tried to save their ships from the madness of the sea and from the eruption of the volcano. As main phase of this volcanic activity, the time interval from 16 January 1866 up to 15 October 1870 is considered (Georgalas, 1962; Skourtis, 1995). (reference #4408)

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
Santorini	Greece	245			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 2026-10-01. NCEI tsunami event 948.