August 15, 1918 Tsunami: Celebes Sea, Philippines
A tsunami caused by a magnitude 8.3 earthquake began at Celebes Sea, Philippines on August 15, 1918 at 12:18:24 UTC. The water rose as high as 7.2 meters. Its effects were recorded at 10 places in at least 4 countries. It killed 52 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
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
- August 15, 1918, 12:18:24 UTC
- Source
- Celebes Sea, Philippines
- Cause
- Earthquake
- Earthquake
- Magnitude 8.3, 20 km deep
- Maximum water height
- 7.2 m (23.6 ft)
- Runups recorded
- 10
- Tsunami intensity (Soloviev-Imamura)
- 2.5
- Tsunami magnitude (Iida)
- 2.8
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 5.538° N, 123.994° E
The toll
- Deaths
- 6; 52 with the earthquake or eruption that caused it
- Damage
- Moderate (about $1 to $5 million); Severe (about $5 to $25 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.
Reference #414:
1918, August 15, 20:18 [local time, 12:18.2 UTC]. There were strong tremors of very great duration all over Mindanao Island. They were accompanied by an enormous number of aftershocks. The station at Butan, 450 km to the north-northeast of the epicenter, equipped with a Weichert seismograph, registered 600 shocks before the end of August; 250 of these registered on the 15th and 16th.
The earthquake did great damage on the coast of the Celebes Sea between Cotabato and Davao Bay and was accompanied by colossal sea waves, which washed away everything on the coast between Lebac and Glan Ports.
The tsunami reached a height of 7 m (24 feet) at some places, and it reached a height of 5 1/2 m (18 feet) at the police station at Glan. It destroyed all that remained of the buildings after the earthquake, swamped people, cattle, horses and other domestic animals, washed away stocks of food, and ruined the harvest in low-lying places. All boats were smashed or washed out to sea. Large rivers disappeared completely and reappeared.
At Lebac Port, near the sawmill, the tsunami had a height of 2-2.5 m (from 6 to 8 feet). Six people died. Much sawwood was tossed a large distance inland. South of Lebac, according to reports, the tsunami reached a height of 6-7 m (20-25 feet).
The tsunami was observed on the north coast of Sulawesi Island: at Paleleh and Bocat at 21:00, at Manado at 21:15 and also at Buol. Several unusual rises and falls in sea level to a height of about 1 m occurred in 15-30 minutes at Manado. At Buol, the oscillations in level were much stronger and did material damage. The majority of reports mentioned three waves.
The tsunami was registered in Japan by at least two tide gauges.
The waves were also registered by the tide gauge at Honolulu with a period of 17 minutes and a height of less than 10 cm.
Reference #150:
1918, August 15, SW. coast of Mindanao 7.2m, 100 deaths. Labuk 2m. Tsunami reached Japan and Honolulu.
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 |
|---|---|---|---|---|---|---|---|
| Lebac, Mindanao Island | Philippines | 121 | 2.5 | 6 | |||
| Glan, Mindanao Island | Philippines | 135 | 5.5 | Eyewitness observation of water height | |||
| Manado, Sulawesi Island | Indonesia | 457 | 1 | Eyewitness observation of water height | day 15, 21:15 | ||
| Surigao, Mindanao Island | Philippines | 498 | |||||
| Paleleh, Sulawesi Island | Indonesia | 546 | Eyewitness observation of water height | day 15, 21:00 | |||
| Buol, Sulawesi Island | Indonesia | 561 | Eyewitness observation of water height | day 15, 21:15 | |||
| Bocat, Sulawesi Island | Indonesia | 565 | Eyewitness observation of water height | ||||
| Hososhima | Japan | 3,083 | 0.07 | Tide gauge (half the maximum wave height) | day 15, 16:24 | ||
| Kushimoto | Japan | 3,324 | 0.2 | Tide gauge (half the maximum wave height) | day 15, 16:30 | ||
| Honolulu, Oahu, HI, HI | United States | 8,566 | 0.1 | Tide gauge (half the maximum wave height) |
More
Every tsunami in 1918The 1900sTsunamis of PhilippinesThe 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 2026-10-01. NCEI tsunami event 1456.