Reviewed by USGSPapua New Guinea58y ago
M7.0 earthquake 42 km WNW of Wewak, Papua New Guinea
Wednesday, October 23, 1968, 21:04:43 UTC · 3.346°S, 143.310°E
A magnitude 7.0 earthquake struck 42 km WNW of Wewak, Papua New Guinea on Wednesday, October 23, 1968, 21:04:43 UTC, at a depth of 13.1 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on September 20, 1935.
- Magnitude
- 7.0
- Major · mw
- Depth
- 13 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VII
- Very strong (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
477 kilotons of TNT
That is about 32 times the Hiroshima bomb. It released about 1,000 times the energy of a magnitude 5.0.
Tectonic setting
26 km
from the nearest mapped plate boundary, between the North Bismarck and Woodlark plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
13 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 200 km
USGS lists 1 M2.5+ earthquake within 200 km in the following 30 days; the largest was M5.7 on October 24, 1968. 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 82 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 · 222 km W of this epicenter
- 7.650 km N of Wewak, Papua New GuineaJuly 3, 1918 · 40 km NE of this epicenter
- 7.593 km SW of Aitape, Papua New GuineaJuly 29, 1917 · 180 km W of this epicenter
- 7.349 km NNE of Angoram, Papua New GuineaMay 7, 1907 · 109 km E of this epicenter
- 7.1132 km NNE of Wewak, Papua New GuineaAugust 26, 1906 · 136 km NE of this epicenter
- 7.143 km SW of Aitape, Papua New GuineaAugust 7, 1931 · 142 km W of this epicenter
- 7.165 km ENE of Wewak, Papua New GuineaApril 27, 1909 · 96 km E of this epicenter
- 7.061 km W of Angoram, Papua New GuineaJune 9, 1925 · 89 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 11 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 27 recorded deaths. The most severe:
- 1930M6.5
Bismarck Sea
23 Dec 1930 · 253 km away
27 deathsModerate damage ($1–5M)tsunami
- 1968M7.5
N Coast, Wewak, Dagua
23 Oct 1968 · 6 km away
Moderate damage ($1–5M)
- 1907M7.4
Bismarck Sea
15 Dec 1907 · 94 km away
Moderate damage ($1–5M)tsunami
- 1951M6.1
Bismarck Sea
22 Feb 1951 · 119 km away
Limited damage (under $1M)tsunami
- 1919
Irian Jaya Region
21 Nov 1919 · 298 km away · intensity VIII
Limited damage (under $1M)tsunami
- 1935M7.8
N-Central
20 Sep 1935 · 217 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.