August 20, 1937 Tsunami: W. Luzon Island, Philippines
A tsunami caused by a magnitude 7.5 earthquake began at W. Luzon Island, Philippines on August 20, 1937 at 11:59:16 UTC. Its effects were recorded at 2 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
- August 20, 1937, 11:59:16 UTC
- Source
- W. Luzon Island, Philippines
- Cause
- Earthquake
- Earthquake
- Magnitude 7.5, 60 km deep
- Runups recorded
- 2
- Tsunami intensity (Soloviev-Imamura)
- 1
- Tsunami magnitude (Iida)
- 0.5
- Waters
- Ocean
- How certain
- Probable tsunami
- Source location
- 14.500° N, 121.500° E
The toll
- Deaths
- 1 with the earthquake or eruption that caused it
- Injuries
- 200 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
- Houses damaged
- 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.
Reference #414:
1937, August 20. There was a strong earthquake with source apparently near Alabat Island. On this island the force of tremors was 7-8 degrees (VIII-IX Rossi-Forel). The earthquake affected the sea. There were reports of a rise in water level at Quezon, on the south of Alabat Island and at the top of Calauag Bay. At Calauag, the level rose from the ebb tide mark to the flood tide mark in 10 minutes. Some rafts, on which several people were traveling up the Calauog River, were picked up by a strong flood current.
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 |
|---|---|---|---|---|---|---|---|
| Quezon, Alabat Island | Philippines | 84 | Eyewitness observation of water height | ||||
| Calaug | Philippines | 104 | Eyewitness observation of water height |
More
Every tsunami in 1937The 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 1699.