Reviewed by USGSPapua New Guinea50y ago
M4.8 earthquake 131 km WNW of Panguna, Papua New Guinea
Wednesday, August 11, 1976, 19:53:00 UTC · 6.066°S, 154.324°E
A magnitude 4.8 earthquake struck 131 km WNW of Panguna, Papua New Guinea on Wednesday, August 11, 1976, 19:53:00 UTC, at a depth of 22.0 km (shallow). It is the strongest earthquake within 300 km since an M5.3 on August 1, 1976.
- Magnitude
- 4.8
- Light · mb
- Depth
- 22 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
239 tons of TNT
That is about 1/63 of the Hiroshima bomb. A magnitude 5.0 releases about 2 times more energy.
Tectonic setting
24 km
from the nearest mapped plate boundary, between the Pacific and North Bismarck plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
22 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS lists 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.8 on August 29, 1976. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 620 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.21919 Papua New Guinea EarthquakeMay 6, 1919 · 149 km N of this epicenter
- 8.11971 Bougainville EarthquakeJuly 26, 1971 · 184 km NW of this epicenter
- 8.01971 New Britain EarthquakeJuly 14, 1971 · 84 km NW of this epicenter
- 8.060 km SE of Kokopo, Papua New GuineaJanuary 1, 1916 · 238 km NW of this epicenter
- 7.956 km WSW of Panguna, Papua New GuineaJuly 20, 1975 · 100 km SE of this epicenter
- 7.885 km S of Panguna, Papua New GuineaJanuary 30, 1939 · 163 km SE of this epicenter
- 7.874 km SSW of Kokopo, Papua New GuineaFebruary 2, 1920 · 283 km NW of this epicenter
- 7.794 km SSW of Panguna, Papua New GuineaJuly 20, 1975 · 147 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 24 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 8 recorded deaths. The most severe:
- 1939M7.7
Bougainville Island
30 Jan 1939 · 163 km away
5 deathsModerate damage ($1–5M)tsunami
- 1971M7.9
New Ireland: Bougainville
14 Jul 1971 · 78 km away · intensity IX
3 deathsUnder $1 million damagetsunami
- 1975M7.9
Bismarck Sea: Bougainville
20 Jul 1975 · 100 km away · intensity VIII
Severe damage ($5–24M)tsunami
- 1959M7.3
Solomon Islands
17 Aug 1959 · 244 km away
Severe damage ($5–24M)tsunami
- 1967M6.4
Bismarck Sea
13 Aug 1967 · 274 km away
Severe damage ($5–24M)tsunami
- 1971M8.1
Bismarck Sea Rabaul
26 Jul 1971 · 184 km away · intensity VI
$1 million damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.