Reviewed by USGSPapua New Guinea40y ago
M4.6 earthquake 61 km WNW of Ambunti, Papua New Guinea
Wednesday, July 9, 1986, 00:24:35 UTC · 4.042°S, 142.294°E
A magnitude 4.6 earthquake struck 61 km WNW of Ambunti, Papua New Guinea on Wednesday, July 9, 1986, 00:24:35 UTC, at a depth of 118.4 km (intermediate). It is the strongest earthquake within 300 km since an M5.3 on July 6, 1986.
- Magnitude
- 4.6
- Light · mb
- Depth
- 118 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 earthquake
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
128 km
from the nearest mapped plate boundary, between the North Bismarck and Woodlark plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
118 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 274 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 · 103 km W of this epicenter
- 7.7120 km SW of Abepura, IndonesiaJanuary 10, 1971 · 299 km W of this epicenter
- 7.650 km N of Wewak, Papua New GuineaJuly 3, 1918 · 177 km NE of this epicenter
- 7.593 km SW of Aitape, Papua New GuineaJuly 29, 1917 · 73 km NW of this epicenter
- 7.349 km NNE of Angoram, Papua New GuineaMay 7, 1907 · 221 km E of this epicenter
- 7.244 km SSW of Angoram, Papua New GuineaJune 24, 1986 · 188 km E of this epicenter
- 7.1132 km NNE of Wewak, Papua New GuineaAugust 26, 1906 · 272 km NE of this epicenter
- 7.1214 km NW of Kiunga, Papua New GuineaJune 25, 1976 · 252 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 6,138 recorded deaths. The most severe:
- 1976M7.1
New Guinea: Irian Jaya
25 Jun 1976 · 252 km away
6,000 deathsSevere damage ($5–24M)
- 1976M7.1
New Guinea: Irian Jaya: Jayawijaya
29 Oct 1976 · 269 km away · intensity VIII
133 deathsLimited damage (under $1M)
- 1900M6.9
Nw. Irian Jaya
7 Oct 1900 · 254 km away
5 deathsLimited damage (under $1M)tsunami
- 1968M7.5
N Coast, Wewak, Dagua
23 Oct 1968 · 133 km away
Moderate damage ($1–5M)
- 1907M7.4
Bismarck Sea
15 Dec 1907 · 107 km away
Moderate damage ($1–5M)tsunami
- 1986M7.1
Papua New Guinea
24 Jun 1986 · 188 km away · intensity VII
Under $1 million damage
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.