Reviewed by USGSPapua New Guinea50y ago
M4.6 earthquake 133 km NW of Panguna, Papua New Guinea
Tuesday, July 6, 1976, 02:16:23 UTC · 5.540°S, 154.562°E
A magnitude 4.6 earthquake struck 133 km NW of Panguna, Papua New Guinea on Tuesday, July 6, 1976, 02:16:23 UTC, at a depth of 111.0 km (intermediate). It is the strongest earthquake within 300 km since an M4.9 on June 13, 1976.
- Magnitude
- 4.6
- Light · mb
- Depth
- 111 km
- Intermediate
- 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
120 tons of TNT
That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.
Tectonic setting
5 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: intermediate
111 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M5.0 on July 25, 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 590 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 · 113 km NW of this epicenter
- 8.11971 Bougainville EarthquakeJuly 26, 1971 · 170 km NW of this epicenter
- 8.01971 New Britain EarthquakeJuly 14, 1971 · 78 km W of this epicenter
- 8.060 km SE of Kokopo, Papua New GuineaJanuary 1, 1916 · 231 km W of this epicenter
- 7.956 km WSW of Panguna, Papua New GuineaJuly 20, 1975 · 129 km SE of this epicenter
- 7.885 km S of Panguna, Papua New GuineaJanuary 30, 1939 · 195 km SE of this epicenter
- 7.874 km SSW of Kokopo, Papua New GuineaFebruary 2, 1920 · 289 km W of this epicenter
- 7.794 km SSW of Panguna, Papua New GuineaJuly 20, 1975 · 186 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 28 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 516 recorded deaths. The most severe:
- 1937
Keravia, Rabaul, Kokopo
28 May 1937 · 297 km away · intensity VIII
507 deathsLimited damage (under $1M)tsunami
- 1939M7.7
Bougainville Island
30 Jan 1939 · 194 km away
5 deathsModerate damage ($1–5M)tsunami
- 1971M7.9
New Ireland: Bougainville
14 Jul 1971 · 73 km away · intensity IX
3 deathsUnder $1 million damagetsunami
- 1878
Bismarck Sea
4 Feb 1878 · 294 km away
1 deathtsunami
- 1975M7.9
Bismarck Sea: Bougainville
20 Jul 1975 · 129 km away · intensity VIII
Severe damage ($5–24M)tsunami
- 1959M7.3
Solomon Islands
17 Aug 1959 · 270 km away
Severe damage ($5–24M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.