October 720 Tsunami: Hebrides (Scotland), United Kingdom
A tsunami probably caused by an earthquake began at Hebrides (Scotland), United Kingdom in October 720.
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
- October 720
- Source
- Hebrides (Scotland), United Kingdom
- Cause
- Questionable earthquake
- Earthquake
- The earthquake
- Runups recorded
- 0
- Waters
- Ocean
- How certain
- Probable tsunami
- Source location
- 56.330° N, 6.410° W
The toll
The record gives no deaths, injuries or damage for this tsunami.
What the record says
NCEI’s account, from the sources it cites.
The Chronicon Scotorum records the following event for 720: Muirbrucht in mense Octimbris. [Translated as:] A belch/bursting forth/huge tidal wave/eruption of the sea in the month of October. The Annals of Tigernach and of Ulster have the following for the same year, up to a minor spelling difference: Murbrucht mor in mense Octimbris. [Translated as:] A great belch/bursting forth/huge tidal wave/eruption of the sea in the month of October. The given translations of brucht are from O Donaill (1977); the meaning “sudden rushing forth, any sudden burst or disruption”, Dwelly (1994), is retained in Scottish Gaidhlig, the language derived from the Irish first brought to Scotland by the Ionan monks and their associated settlers […] The common record in the three annals is clearly indicative of a tsunami; the only other slight interpretative possibility is of a major storm surge, but no storm is mentioned in conjunction with it; and the implied suddenness argues further against this interpretation. (reference #13465)
More
Every tsunami in 720The 700sTsunamis of United KingdomThe earthquakeAlerts 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 5874.