M4.6 earthquake 15 km NE of Biak, Indonesia

Thursday, September 27, 1979, 14:24:24 UTC · 1.094°S, 136.192°E

A magnitude 4.6 earthquake struck 15 km NE of Biak, Indonesia on Thursday, September 27, 1979, 14:24:24 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.5 on September 19, 1979.

Magnitude: 4.6; Light · mb
Depth: 33 km; Shallow
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: 50 km aftershock search area

In context

How big was it, and why here?

Energy released

120 tons of TNT

That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.

Tectonic setting

99 km

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

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 50 km

USGS lists 7 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M6.0 on October 17, 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 114 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 · 133 km away · intensity VII
250 deathsSevere damage ($5–24M)tsunami
1979M7.9
New Guinea: Irian Jaya
12 Sep 1979 · 67 km away
115 deathsSevere damage ($5–24M)tsunami
1957M7.3
New Guinea: Irian Jaya
22 Jun 1957 · 101 km away
Severe damage ($5–24M)tsunami
1914M8.1
New Guinea: Irian Jaya: Japen
26 May 1914 · 117 km away · intensity IX
Moderate damage ($1–5M)tsunami
1916M8.1
New Guinea: Irian Jaya
13 Jan 1916 · 213 km away
1916M8.1
New Guinea: Irian Jaya
13 Jan 1916 · 225 km away

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

Nearby trackers