December 21, 1812 Tsunami: S. California, United States
A tsunami caused by a magnitude 7.5 earthquake and a landslide began at S. California, United States on December 21, 1812 at 19:00 UTC. The water rose as high as 3.4 meters. Its effects were recorded at 5 places. It killed 1 person, 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
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
- December 21, 1812, 19:00 UTC
- Source
- S. California, United States
- Cause
- Earthquake and landslide
- Earthquake
- Magnitude 7.5
- Maximum water height
- 3.4 m (11.2 ft)
- Runups recorded
- 5
- Tsunami intensity (Soloviev-Imamura)
- 1.5
- Tsunami magnitude (Iida)
- 1.8
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 34.200° N, 119.900° W
The toll
- Deaths
- 1 with the earthquake or eruption that caused it
- Damage
- Limited (under about $1 million); Moderate (about $1 to $5 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 7.7 magnitude earthquake, one of two on this date, destroyed the Mission Purisima Concepcion and damaged the Mission and Presidio of Santa Barbara and Mission San Buenaventura (Ventura). An American ship at El Refugio, likely involved in smuggling operations, drifted ashore and up a canyon.
Trask (Ref #2541) reports that this earthquake occurred in September -- the event has apparently been attributed to September, October, or December (Ref #79). He gives a long accounting of the event, including the action of the waves at Santa Barbara.
1812, December 21, 10:30 (local time). There was a strong earthquake in the south of California, accompanied by an "enormous" tsunami in the Santa Barbara Strait (according to other sources, the tsunami was caused not by the first, but by a second, more powerful earthquake at 10:45 local time). (Reference #415)
Ref #1128 states: “This earthquake may or may not have generated a tsunami. A recent examination of evidence for a tsunami by Marine Advisers, Inc. (1965) neither proves nor disproves the occurrence of tsunami waves. Mission records at that time mention fear of the sea, but give no details. Reports of a tsunami, which do not appear in the literature until many years after the earthquake, are based on the memory of several individuals. In light of the examination, statements concerning a tsunami in previous issues of the present report (Publication 41-2, Part 11) should be considered as lacking adequate proof.”
P. Gil reported that there was a huge earthquake wave at sea. A stick with a pendant ball was set up at the Mission (Santa Barbara), and the ball vibrated continually for eight days, and later, at intervals for fifteen days. A ship at Refugio (IX) was carried up a caiaon by the wave and returned to sea., H. H. B. (reference #2967)
This earthquake was associated with by far the largest seismic sea wave ever reported for one originating in California . Descriptive accounts indicate that it may have reached land elevations of 50 feet at Gaviota , 30–35 feet at Santa Barbara , and 15 or more feet at Ventura . It may even have shown visible effects in San Francisco Harbor . (reference #13542)
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 |
|---|---|---|---|---|---|---|---|
| Santa Rosa Island, CA, CA | United States | 29 | Eyewitness observation of water height | ||||
| Santa Barbara, CA, CA | United States | 32 | 2 | Eyewitness observation of water height | |||
| El Refugio (Gaviota), CA, CA | United States | 41 | 3.4 | Eyewitness observation of water height | |||
| Ventura, CA, CA | United States | 58 | 2 | Eyewitness observation of water height | |||
| Hookena, Hawaii, HI, HI | United States | 3,911 | 3 | Eyewitness observation of water height |
More
Every tsunami in 1812The 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 609.