October 25, 1918 Tsunami: Puerto Rico, US Territories
A tsunami caused by a magnitude 6.4 earthquake began at Puerto Rico, US Territories on October 25, 1918 at 03:43 UTC. Its effects were recorded at 2 places in at least 2 countries.
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 25, 1918, 03:43 UTC
- Source
- Puerto Rico, US Territories
- Cause
- Earthquake
- Earthquake
- Magnitude 6.4, 15 km deep
- Runups recorded
- 2
- Waters
- Ocean
- How certain
- Probable tsunami
- Source location
- 18.441° N, 67.214° W
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.
Reference #1492:
1918, October 24 23:43 local time. 18.5 N, 67.5 W. Validity 4. Considered a terrific aftershock of the Oct. 11 event, both this and another earthquake on Nov. 12 had epicentral intensities of R-F ~VIII to IX. In marked contrast to the vertical vibrations of the initial disturbance, these were characterized by horizontal oscillations. A small wave
was recorded at the Galveston, Texas, tide gauge. Taber said these two shocks were not accompanied by "sea-waves," although it has been suggested that, at that time of night, a small wave may have escaped notice. Submarine cables were again cut, possibly indicating submarine slumping. The steamer, Mariana, 11 km southwest of the Isla Mona Lighthouse, plunged and rolled heavily. Heck reported Oct. 25. Forster, 1890; Heck, 1947; Lander & Lockridge, 1989; Lander & Obughlin, 1999e; Lynch & Shepherd, 1995; Mercado Irizarry, 1999; Port-ofSpain Gazette, 1918; Reid and Taber, 1919a&b; Taber, 1922b.
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 |
|---|---|---|---|---|---|---|---|
| Mona Passage, PR | US Territories | 57 | Eyewitness observation of water height | ||||
| Galveston, TX, TX | United States | 3,044 | Tide gauge (half the maximum wave height) |
More
Every tsunami in 1918The 1900sTsunamis of US TerritoriesThe 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 1459.