M7.9 earthquake 55 km S of Biak, Indonesia

Wednesday, September 12, 1979, 05:17:51 UTC · 1.679°S, 136.040°E

A magnitude 7.9 earthquake struck 55 km S of Biak, Indonesia on Wednesday, September 12, 1979, 05:17:51 UTC, at a depth of 5.0 km (shallow). It is the strongest earthquake within 300 km since an M8.2 on May 26, 1914.

Magnitude: 7.9; Major · ms
Depth: 5 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

11 megatons of TNT

That is about 709 times the Hiroshima bomb. It released about 22,387 times the energy of a magnitude 5.0.

Tectonic setting

132 km

from the nearest mapped plate boundary, between the Maoke and Birds Head plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: shallow

5 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 19 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.9 on September 13, 1979. 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 125 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 7 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 365 recorded deaths. The most severe:

1864M7.8
Irian Jaya: Manokwari
23 May 1864 · 138 km away · intensity VII
250 deathsSevere damage ($5–24M)tsunami
1979M7.9
New Guinea: Irian Jaya
12 Sep 1979 · 0 km away
115 deathsSevere damage ($5–24M)tsunami
1957M7.3
New Guinea: Irian Jaya
22 Jun 1957 · 109 km away
Severe damage ($5–24M)tsunami
1914M8.1
New Guinea: Irian Jaya: Japen
26 May 1914 · 102 km away · intensity IX
Moderate damage ($1–5M)tsunami
1916M8.1
New Guinea: Irian Jaya
13 Jan 1916 · 147 km away
1916M8.1
New Guinea: Irian Jaya
13 Jan 1916 · 159 km away

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

Nearby trackers