October 8, 1865 Tsunami: N. California, United States
A tsunami caused by a magnitude 6.3 earthquake and a landslide began at N. California, United States on October 8, 1865 at 20:46 UTC. 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
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
- October 8, 1865, 20:46 UTC
- Source
- N. California, United States
- Cause
- Earthquake and landslide
- Earthquake
- Magnitude 6.3
- Runups recorded
- 1
- Tsunami intensity (Soloviev-Imamura)
- 0.5
- Waters
- Ocean
- How certain
- Probable tsunami
- Source location
- 37.200° N, 121.900° W
The toll
- Damage
- $500,000 with the earthquake or eruption that caused it
- Houses destroyed
- Some (about 51 to 100) 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 occured near Santa Cruz. The account of collapsing cliffs and a high flood tide and then a strong ebb tide is consistent with a subaerial landslide-generated tsunami. There is no marigram from Fort Point as the clock stopped for several hours when the earthquake began. There was probably a subaerial landslide tsunami at Santa Cruz and possibly a submarine landslide tsunami generated near San Francisco.
Below from reference #415:
1865, October 4, 12:45 local time. There was a destructive earthquake in California, possibly caused by a small shift along the San Andreas fault in the Santa Cruz region...There were abundant rock falls in the mountains. The ground along the river cracked, and gryphons spurted. The water splashed out of small bodies of water, or they were covered with sand. The water level dropped in wells.
The effect of the earthquake on the water of Mission Bay and on Long Bridge was terrifying.
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 Cruz, CA, CA | United States | 28 | Eyewitness observation of water height |
More
Every tsunami in 1865The 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 940.