August 21, 1902 Tsunami: Illana Bay, Celebes Sea, Philippines
A tsunami caused by a magnitude 7.3 earthquake began at Illana Bay, Celebes Sea, Philippines on August 21, 1902 at 11:17 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
- August 21, 1902, 11:17 UTC
- Source
- Illana Bay, Celebes Sea, Philippines
- Cause
- Earthquake
- Earthquake
- Magnitude 7.3
- Runups recorded
- 1
- Tsunami intensity (Soloviev-Imamura)
- 2
- Waters
- Ocean
- How certain
- Very doubtful tsunami
- Source location
- 7.500° N, 123.500° E
The toll
- Deaths
- Many (about 101 to 1,000) with the earthquake or eruption that caused it
- Damage
- Severe (about $5 to $25 million) 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.
1902, August 21, 19:17 [local time], 7.5 N, 123.5 E, magnitude 7.25. There was an earthquake with a maximal intensity of 9 degrees (X Rossi-Forel) on the south of Mindanao Island, in the provinces of Lanao and Cotabato. Its source was situated in the northern part of Illana Bay. Sieberg, in relating this information, adds that a tsunami occurred. There is thus no reliable information about a tsunami, although one cannot entirely eliminate the possibility. Listed as questionable tsunami. (reference #414)
1902, August 21, S.W. Mindanao, Celebes Sea. Illama Bay, Mindanao - no details. (reference #79)
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 |
|---|---|---|---|---|---|---|---|
| Illana Bay | Philippines | 30 | Eyewitness observation of water height |
More
Every tsunami in 1902The 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 2026-09-24. NCEI tsunami event 1290.