M5.3 earthquake 124 km WNW of Panguna, Papua New Guinea

Thursday, August 21, 1975, 06:48:30 UTC · 5.879°S, 154.446°E

A magnitude 5.3 earthquake struck 124 km WNW of Panguna, Papua New Guinea on Thursday, August 21, 1975, 06:48:30 UTC, at a depth of 430.0 km (deep). It is the strongest earthquake within 300 km since an M5.3 on August 10, 1975.

Magnitude: 5.3; Moderate · mb
Depth: 430 km; Deep
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: 75 km aftershock search area

In context

How big was it, and why here?

Energy released

1 kilotons of TNT

That is about 1/11 of the Hiroshima bomb. It released about 3 times the energy of a magnitude 5.0.

Tectonic setting

11 km

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

Depth: deep

430 km

Deep earthquakes (over 300 km) happen deep inside subducting plates. They rarely cause damage, but can be felt faintly over very large distances.

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 75 km

USGS lists 2 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.1 on September 5, 1975. 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 534 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 24 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 8 recorded deaths. The most severe:

1939M7.7
Bougainville Island
30 Jan 1939 · 169 km away
5 deathsModerate damage ($1–5M)tsunami
1971M7.9
New Ireland: Bougainville
14 Jul 1971 · 74 km away · intensity IX
3 deathsUnder $1 million damagetsunami
1975M7.9
Bismarck Sea: Bougainville
20 Jul 1975 · 104 km away · intensity VIII
Severe damage ($5–24M)tsunami
1959M7.3
Solomon Islands
17 Aug 1959 · 249 km away
Severe damage ($5–24M)tsunami
1967M6.4
Bismarck Sea
13 Aug 1967 · 271 km away
Severe damage ($5–24M)tsunami
1971M8.1
Bismarck Sea Rabaul
26 Jul 1971 · 179 km away · intensity VI
$1 million damagetsunami

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

Nearby trackers