Reviewed by USGSPapua New Guinea40y ago
M4.7 earthquake 53 km SSW of Angoram, Papua New Guinea
Saturday, August 2, 1986, 18:49:23 UTC · 4.481°S, 143.830°E
A magnitude 4.7 earthquake struck 53 km SSW of Angoram, Papua New Guinea on Saturday, August 2, 1986, 18:49:23 UTC, at a depth of 129.7 km (intermediate). It is the strongest earthquake within 300 km since an M4.8 on July 14, 1986.
- Magnitude
- 4.7
- Light · mb
- Depth
- 130 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
169 tons of TNT
That is about 1/89 of the Hiroshima bomb. A magnitude 5.0 releases about 3 times more energy.
Tectonic setting
81 km
from the nearest mapped plate boundary, between the South Bismarck and Woodlark plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: intermediate
130 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 M3.8 on August 8, 1986. 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 282 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8New Guinea, Papua New GuineaSeptember 20, 1935 · 280 km W of this epicenter
- 7.650 km N of Wewak, Papua New GuineaJuly 3, 1918 · 157 km N of this epicenter
- 7.593 km SW of Aitape, Papua New GuineaJuly 29, 1917 · 248 km W of this epicenter
- 7.349 km NNE of Angoram, Papua New GuineaMay 7, 1907 · 103 km NE of this epicenter
- 7.244 km SSW of Angoram, Papua New GuineaJune 24, 1986 · 13 km E of this epicenter
- 7.1132 km NNE of Wewak, Papua New GuineaAugust 26, 1906 · 225 km N of this epicenter
- 7.143 km SW of Aitape, Papua New GuineaAugust 7, 1931 · 235 km NW of this epicenter
- 7.165 km ENE of Wewak, Papua New GuineaApril 27, 1909 · 135 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 18 recorded deaths. The most severe:
- 1970M7.3
Madang
31 Oct 1970 · 188 km away · intensity VIII
18 deaths$2 million damagetsunami
- 1873M8.0
Maclay Coast
1873 · 266 km away · intensity IX
Moderate damage ($1–5M)tsunami
- 1968M7.5
N Coast, Wewak, Dagua
23 Oct 1968 · 134 km away
Moderate damage ($1–5M)
- 1907M7.4
Bismarck Sea
15 Dec 1907 · 213 km away
Moderate damage ($1–5M)tsunami
- 1984M6.6
Karkar
27 Mar 1984 · 220 km away · intensity VIII
Moderate damage ($1–5M)
- 1979M6.2
E, Mt Hagen
25 Jun 1979 · 201 km away
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.