July 4, 1809 Tsunami: Portugal
A tsunami of unknown cause began at Portugal on July 4, 1809.
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
The tsunami
- Date
- July 4, 1809
- Source
- Portugal
- Cause
- Unknown
- Runups recorded
- 0
- Waters
- Ocean
- How certain
- Very doubtful tsunami
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.
1809 July 4. Portugal. No shock listed. An extraordinary flux and reflux of the sea was observed near Lisbon. (#41)
Berninghausen (1964, ref #41), quoting Mallet (1852), reports a tsunami in Portugal on 4 July 1809. The description is: “[. . . ] Portugal. No shock listed. An extraordinary flux and reflux of the sea is observed near Lisbon [. . . ]”. The Portuguese newspaper for this month Gazeta de Lisboa, July 1809, does not report any sea disturbance. In Rodriguez (1932), quoting Perrey (1847) there is only one event reported for Lisbon on 26 October the same year, but no reference to any sea disturbance. Mallet (1852) mentions a flux and reflux in Spezia near Genoa and says that the same phenomenon was observed in Lisbon. As there is no evidence of any Portuguese historical source, we shall not consider this event in the catalog. (reference #4649)
More
Every tsunami in 1809The 1800sTsunamis of PortugalThis 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 601.