September 25, 1971 Tsunami: Bismarck Sea, Papua New Guinea

Name: September 25, 1971 Tsunami: Bismarck Sea, Papua New Guinea
Start: 1971-09-25
Location: Bismarck Sea, Papua New Guinea

September 25, 1971 · 1.8 m · Questionable tsunami

A tsunami caused by a magnitude 7 earthquake and a landslide began at Bismarck Sea, Papua New Guinea on September 25, 1971 at 04:36:14 UTC. The water rose as high as 1.8 meters. 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

Tsunami warnings in force

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: September 25, 1971, 04:36:14 UTC
Source: Bismarck Sea, Papua New Guinea
Cause: Earthquake and landslide
Earthquake: Magnitude 7, 115 km deep
Maximum water height: 1.8 m (5.9 ft)
Runups recorded: 1
Tsunami intensity (Soloviev-Imamura): 0.5
Tsunami magnitude (Iida): 0.8
Waters: Ocean
How certain: Questionable tsunami
Source location: 6.500° S, 146.600° E

The toll

Damage: Limited (under about $1 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.

At the time of the earthquake the sea was quite calm. A few minutes after the quake the sea at Bayern Bay, south and southeast of the Salamaua Isthmus suddenly appeared turbulent as if a sudden strong wind had brought the water itno motion. For about five minutes the surf breaking onto the beaches approached the June-July-August high tide mark (about six feet higher than is customary for September and October). The turbulence then subsided although high waves continued for about another ten minutes. Slumping in Huon Gulf induced the tidal effects, which were recorded at Lae tide gauge. 9reference #99)

According to Everingham (reference #2666) this earthquake was reported as tsunamigenic. However, it is doubtful that an earthquake with a magnitude of 6.7 and a hypocenter depth of 115 km could generate any appreciable tsunami. (reference #417)

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
Bayern Bay (Near Salamaua)	Papua New Guinea	80	1.8		Eyewitness observation of water height

Every tsunami in 1971 The 1900s Tsunamis of Papua New Guinea The earthquake This day in weather history Alerts 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 2040.