M5.5 earthquake 65 km SSE of Biak, Indonesia

Wednesday, September 19, 1979, 12:53:18 UTC · 1.749°S, 136.223°E

A magnitude 5.5 earthquake struck 65 km SSE of Biak, Indonesia on Wednesday, September 19, 1979, 12:53:18 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.6 on September 13, 1979.

Magnitude: 5.5; Moderate · mb
Depth: 33 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: V; Moderate (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 75 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

3 kilotons of TNT

That is about 1/6 of the Hiroshima bomb. It released about 6 times the energy of a magnitude 5.0.

Tectonic setting

113 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

33 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 75 km

USGS lists 6 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.7 on October 16, 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 142 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 8 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 · 159 km away · intensity VII
250 deathsSevere damage ($5–24M)tsunami
1979M7.9
New Guinea: Irian Jaya
12 Sep 1979 · 22 km away
115 deathsSevere damage ($5–24M)tsunami
1957M7.3
New Guinea: Irian Jaya
22 Jun 1957 · 91 km away
Severe damage ($5–24M)tsunami
1914M8.1
New Guinea: Irian Jaya: Japen
26 May 1914 · 81 km away · intensity IX
Moderate damage ($1–5M)tsunami
1921
New Guinea: Irian Jaya: Sentani
10 Oct 1921 · 293 km away · intensity VII
Moderate damage ($1–5M)
1916M8.1
New Guinea: Irian Jaya
13 Jan 1916 · 141 km away

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

Nearby trackers