M8.0 earthquake 1971 New Britain Earthquake

Wednesday, July 14, 1971, 06:11:26 UTC · 5.467°S, 153.864°E

A magnitude 8.0 earthquake struck 1971 New Britain Earthquake on Wednesday, July 14, 1971, 06:11:26 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M8.2 on May 6, 1919.

Magnitude: 8.0; Great · mw
Depth: 15 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VI; Strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 400 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

15 megatons of TNT

That is about 1,002 times the Hiroshima bomb. It released about 31,623 times the energy of a magnitude 5.0.

Tectonic setting

37 km

from the nearest mapped plate boundary, between the North Bismarck and South Bismarck plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

15 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 400 km

USGS lists 47 M2.5+ earthquakes within 400 km in the following 30 days; the largest was M8.1 on July 26, 1971. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

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:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 25 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 520 recorded deaths. The most severe:

1937
Keravia, Rabaul, Kokopo
28 May 1937 · 227 km away · intensity VIII
507 deathsLimited damage (under $1M)tsunami
1939M7.7
Bougainville Island
30 Jan 1939 · 246 km away
5 deathsModerate damage ($1–5M)tsunami
1941M7.4
Bismarck Sea
13 Jan 1941 · 245 km away
4 deathsModerate damage ($1–5M)tsunami
1971M7.9
New Ireland: Bougainville
14 Jul 1971 · 5 km away · intensity IX
3 deathsUnder $1 million damagetsunami
1878
Bismarck Sea
4 Feb 1878 · 224 km away
1 deathtsunami
1967M6.4
Bismarck Sea
13 Aug 1967 · 192 km away
Severe damage ($5–24M)tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers