November 11, 1099 Tsunami: West Cornwall, England, United Kingdom
A tsunami of unknown cause began at West Cornwall, England, United Kingdom on November 11, 1099. 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
The tsunami
- Date
- November 11, 1099
- Source
- West Cornwall, England, United Kingdom
- Cause
- Unknown
- Runups recorded
- 1
- Waters
- Ocean
- How certain
- Erroneous entry
- Source location
- 50.116° N, 5.483° W
The toll
- Deaths
- Many (about 101 to 1,000)
- Damage
- Severe (about $5 to $25 million)
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.
Berninghausen (Reference #43) lists as tsunami event, stating: "St. Michael's Mount -- The sea overflowed the shore, destroying towns and drowning many persons and innumerable oxen and sheep." Accounts are vague.
1099 November 11. This relates to a storm mentioned in the Saxon Chronicles as occurring on St Martin’s Festival and is linked with a great storm attributed in Cornish folklore for the loss of the land of Lyonesse. There is no evidence that this flooding was a tsunami event. (reference #14326)
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 |
|---|---|---|---|---|---|---|---|
| Saint Michael'S Mount, England | United Kingdom | 0 | Eyewitness observation of water height |
More
Every tsunami in 1099The 1000sTsunamis of United KingdomThis 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 97.