July 20, 1975 Tsunami: Solomon Sea, Papua New Guinea

Name: July 20, 1975 Tsunami: Solomon Sea, Papua New Guinea
Start: 1975-07-20
Location: Solomon Sea, Papua New Guinea

July 20, 1975 · 2 m · Definite tsunami

A tsunami caused by a magnitude 7.9 earthquake began at Solomon Sea, Papua New Guinea on July 20, 1975 at 14:37:39 UTC. The water rose as high as 2 meters. Its effects were recorded at 19 places in at least 4 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

Tsunami warnings in force

The tsunami

Date: July 20, 1975, 14:37:39 UTC
Source: Solomon Sea, Papua New Guinea
Cause: Earthquake
Earthquake: Magnitude 7.9, 49 km deep
Maximum water height: 2 m (6.6 ft)
Runups recorded: 19
Tsunami intensity (Soloviev-Imamura): 1
Tsunami magnitude (Iida): 1
Waters: Ocean
How certain: Definite tsunami
Source location: 6.590° S, 155.054° E

The toll

Damage: Moderate (about $1 to $5 million); Severe (about $5 to $25 million) with the earthquake or eruption that caused it
Houses destroyed: Few (about 1 to 50); Some (about 51 to 100) 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.

On the southwestern and southern coasts of Bougainville Island, over a stretch of 80 km tsunami waves at heights of 2m and periods of 5 to 15 min hit the coast several times. The tsunami occurred during the period of 1.2 m maximum high-tide which accented its effect. But there was no loss of life due to the 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
Yaba (Jaba) River, Bougainville Is doubtful	Papua New Guinea	30	2		Eyewitness observation of water height
Torokina, Bougainville Island	Papua New Guinea	38	1	60	Eyewitness observation of water height
Mamagota, Bougainville	Papua New Guinea	42	1		Eyewitness observation of water height
Kieta, Bougainville Island	Papua New Guinea	76	0.1		Eyewitness observation of water height
Kwajalein, Marshall Islands, MH	Marshall Islands	2,202	0.06		Tide gauge (half the maximum wave height)
Camp Cove, Sydney Harbor	Australia	3,038			Tide gauge (half the maximum wave height)
Chichijima Island	Japan	3,976	0.05		Tide gauge (half the maximum wave height)
Kushimoto	Japan	4,878	0.06		Tide gauge (half the maximum wave height)
Omaezaki	Japan	4,891	0.05		Tide gauge (half the maximum wave height)
Aburatsu	Japan	4,915	0.08		Tide gauge (half the maximum wave height)
Owase	Japan	4,921	0.04		Tide gauge (half the maximum wave height)
Tosa-Shimizu	Japan	4,945	0.04		Tide gauge (half the maximum wave height)
Onahama	Japan	5,038	0.04		Tide gauge (half the maximum wave height)
Hachinohe	Japan	5,398	0.06		Tide gauge (half the maximum wave height)
Urakawa	Japan	5,541	0.05		Tide gauge (half the maximum wave height)
Hiroo	Japan	5,542	0.06		Tide gauge (half the maximum wave height)	day 20, 22:29
Tokachiko	Japan	5,543	0.05		Tide gauge (half the maximum wave height)
Hanasaki	Japan	5,605	0.11		Tide gauge (half the maximum wave height)
Bougainville Is, South Southwest	Papua New Guinea		2		Eyewitness observation of water height

Every tsunami in 1975 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 2076.