Reviewed by USGSPapua New Guinea55y ago
M6.3 earthquake 141 km S of Kokopo, Papua New Guinea
Monday, August 9, 1971, 20:01:40 UTC · 5.622°S, 152.173°E
A magnitude 6.3 earthquake struck 141 km S of Kokopo, Papua New Guinea on Monday, August 9, 1971, 20:01:40 UTC, at a depth of 29.5 km (shallow). It is the strongest earthquake within 300 km since an M6.3 on August 9, 1971.
- Magnitude
- 6.3
- Strong · mw
- Depth
- 30 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- V
- Moderate (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
38 kilotons of TNT
That is about 3 times the Hiroshima bomb. It released about 80 times the energy of a magnitude 5.0.
Tectonic setting
17 km
from the nearest mapped plate boundary, between the South Bismarck and Solomon Sea plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
30 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 100 km
USGS lists 2 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.8 on August 10, 1971. 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 324 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 · 208 km NE of this epicenter
- 8.11971 Bougainville EarthquakeJuly 26, 1971 · 140 km NE of this epicenter
- 8.01971 New Britain EarthquakeJuly 14, 1971 · 188 km E of this epicenter
- 8.060 km SE of Kokopo, Papua New GuineaJanuary 1, 1916 · 109 km NE of this epicenter
- 7.874 km SSW of Kokopo, Papua New GuineaFebruary 2, 1920 · 75 km N of this epicenter
- 7.7152 km SE of Kokopo, Papua New GuineaSeptember 29, 1946 · 137 km E of this epicenter
- 7.532 km SSW of Kimbe, Papua New GuineaDecember 28, 1945 · 237 km W of this epicenter
- 7.467 km E of Kokopo, Papua New GuineaApril 23, 1953 · 151 km NE 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 515 recorded deaths. The most severe:
- 1937
Keravia, Rabaul, Kokopo
28 May 1937 · 150 km away · intensity VIII
507 deathsLimited damage (under $1M)tsunami
- 1941M7.4
Bismarck Sea
13 Jan 1941 · 161 km away
4 deathsModerate damage ($1–5M)tsunami
- 1971M7.9
New Ireland: Bougainville
14 Jul 1971 · 192 km away · intensity IX
3 deathsUnder $1 million damagetsunami
- 1878
Bismarck Sea
4 Feb 1878 · 153 km away
1 deathtsunami
- 1967M6.4
Bismarck Sea
13 Aug 1967 · 141 km away
Severe damage ($5–24M)tsunami
- 1971M8.1
Bismarck Sea Rabaul
26 Jul 1971 · 140 km away · intensity VI
$1 million damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.