April 20, 1977 Tsunami: Solomon Islands
A tsunami caused by a magnitude 6.8 earthquake began at Solomon Islands on April 20, 1977 at 23:13:10 UTC. The water rose as high as 0.15 meters. Its effects were recorded at 7 places in at least 4 countries. It killed 34 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
The tsunami
- Date
- April 20, 1977, 23:13:10 UTC
- Source
- Solomon Islands
- Cause
- Earthquake
- Earthquake
- Magnitude 6.8, 33 km deep
- Maximum water height
- 0.15 m (0.5 ft)
- Runups recorded
- 7
- Tsunami intensity (Soloviev-Imamura)
- -1
- Tsunami magnitude (Iida)
- -3.3
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 9.828° S, 163.323° E
The toll
- Deaths
- 34 with the earthquake or eruption that caused it
- Damage
- 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.
On April 20, 1977, at 23:13 UTC an earthquake occurred in the Solomon Islands. This was the first of [four] earthquakes that occurred in a five hour period in this region. According to, press information at least 12 people were killed and 22 were missing as a result of these earthquakes. Severe destruction and landslides were reported from Honiara. The first earthquake, with magnitude of 6.5, produced a weak tsunami which was recorded by several tide gauges in Australia and on the Solomon Islands. (reference #417)
Tsunami (7.6 cm peak to peak) at Rabaul. (reference #1053)
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 |
|---|---|---|---|---|---|---|---|
| Honiara, Guadalcanal | Solomon Islands | 372 | 0.15 | Tide gauge (half the maximum wave height) | day 21, 00:15 | ||
| Rabaul, New Britain | Papua New Guinea | 1,378 | 0.04 | Tide gauge (half the maximum wave height) | |||
| Cairns | Australia | 2,054 | 0.02 | Tide gauge (half the maximum wave height) | day 21, 06:37 | ||
| Townsville, Queensland | Australia | 2,058 | 0.06 | Tide gauge (half the maximum wave height) | day 21, 05:25 | ||
| Brisbane | Australia | 2,215 | Tide gauge (half the maximum wave height) | day 21, 08:03 | |||
| Apia, Upolu Island | Samoa | 2,749 | 0.04 | Tide gauge (half the maximum wave height) | day 21, 05:50 | ||
| Fort Denison, Sydney Harbor | Australia | 2,933 | Tide gauge (half the maximum wave height) |
More
Every tsunami in 1977The 1900sTsunamis of Solomon IslandsThe 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 2089.