M7.0 earthquake 55 km NNW of Ambunti, Papua New Guinea

Friday, September 20, 1935, 05:23:10 UTC · 3.743°S, 142.642°E

A magnitude 7.0 earthquake struck 55 km NNW of Ambunti, Papua New Guinea on Friday, September 20, 1935, 05:23:10 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.8 on September 20, 1935.

Magnitude: 7.0; Major · mw
Depth: 35 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: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

511 kilotons of TNT

That is about 34 times the Hiroshima bomb. It released about 1,072 times the energy of a magnitude 5.0.

Tectonic setting

86 km

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

Depth: shallow

35 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 4 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.6 on September 23, 1935. 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 28 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 5 recorded deaths. The most severe:

1900M6.9
Nw. Irian Jaya
7 Oct 1900 · 294 km away
5 deathsLimited damage (under $1M)tsunami
1907M7.4
Bismarck Sea
15 Dec 1907 · 73 km away
Moderate damage ($1–5M)tsunami
1919
Irian Jaya Region
21 Nov 1919 · 248 km away · intensity VIII
Limited damage (under $1M)tsunami
1935M7.8
N-Central
20 Sep 1935 · 136 km away
tsunami
1916M7.5
N Coast
3 Aug 1916 · 208 km away
1917M7.5
Papua New Guinea
29 Jul 1917 · 101 km away
tsunami

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

Nearby trackers