October 21, 1868 Tsunami: N. California, United States
A tsunami caused by a magnitude 6.8 earthquake and a landslide began at N. California, United States on October 21, 1868 at 15:53 UTC. The water rose as high as 4.5 meters. Its effects were recorded at 4 places. It killed 30 people, counting the earthquake or eruption that caused it.
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
- October 21, 1868, 15:53 UTC
- Source
- N. California, United States
- Cause
- Earthquake and landslide
- Earthquake
- Magnitude 6.8
- Maximum water height
- 4.5 m (14.8 ft)
- Runups recorded
- 4
- Tsunami intensity (Soloviev-Imamura)
- 0.5
- Tsunami magnitude (Iida)
- 2.2
- Waters
- Ocean
- How certain
- Probable tsunami
- Source location
- 37.700° N, 122.100° W
The toll
- Deaths
- 30 with the earthquake or eruption that caused it
- Damage
- $350,000 with the earthquake or eruption that caused it
- Houses destroyed
- Many (101 to 1,000) 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 destructive earthquake occurred on the Hayward fault producing a scarp 20 miles [32 km] long with a three foot [0.9 m] horizontal offset and apparently a slight downthrow on the southwestern side. It generated a tsunami that was observed in San Francisco, Sacramento, and Santa Cruz, California. (Reference #237).
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 |
|---|---|---|---|---|---|---|---|
| Government Island, CA, CA | United States | 14 | Tide gauge (half the maximum wave height) | ||||
| San Francisco Bay, CA, CA | United States | 15 | 4.5 | Eyewitness observation of water height | |||
| Santa Cruz, CA, CA | United States | 81 | Eyewitness observation of water height | ||||
| Sacramento, CA, CA | United States | 111 | 0.61 | Other |
More
Every tsunami in 1868The 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 993.