September 24, 1859 Tsunami: Half Moon Bay, N. California, United States
A tsunami of unknown cause began at Half Moon Bay, N. California, United States on September 24, 1859. The water rose as high as 4.6 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
The tsunami
- Date
- September 24, 1859
- Source
- Half Moon Bay, N. California, United States
- Cause
- Unknown
- Earthquake
- The earthquake
- Maximum water height
- 4.6 m (15.1 ft)
- Runups recorded
- 1
- Tsunami intensity (Soloviev-Imamura)
- 0
- Tsunami magnitude (Iida)
- 2.2
- Waters
- Ocean
- How certain
- Questionable tsunami
The toll
- Damage
- Limited (under about $1 million) 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.
A Schooner lying in Half Moon Bay was damaged. An earthquake occured around 5:50 A.M. but marigram records cannot confirm a resultant tsunami. However, a plot of expected tides at Fort Point shows a minus six inch tide expected at 3:30 A.M. which could have caused the schooner's plight. This report could be for a local submarine landslide tsunami or a normal tide fluctuation unrelated to the earthquake.
1859, September 24, 3:00 local time (or October 18, 6:00 local time). There was an earthquake at San Francisco and Half Moon Bay. The schooner "Black Warrior" was riding at anchor in Half Moon Bay. Suddenly the water retreated 4 1/2 m (15 feet) and the ship found itself on dry bottom, where it stayed for several seconds. Then the water returned so fast that it damaged the schooner (Reference #415).
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 |
|---|---|---|---|---|---|---|---|
| Half Moon Bay, CA, CA | United States | 4.6 | Eyewitness observation of water height |
More
Every tsunami in 1859The 1800sTsunamis of United StatesThe earthquakeThis 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 886.