QuakeScout
Magnitude6.4

Reviewed by USGSPapua New Guinea92y ago

M6.4 earthquake 20 km SSE of Ambunti, Papua New Guinea

Friday, September 20, 1935, 21:04:06 UTC · 4.388°S, 142.881°E

A magnitude 6.4 earthquake struck 20 km SSE of Ambunti, Papua New Guinea on Friday, September 20, 1935, 21:04:06 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on September 20, 1935.

Magnitude
6.4
Strong · mw
Depth
15 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: 100 km aftershock search area

In context

How big was it, and why here?

Energy released

52 kilotons of TNT

That is about 3 times the Hiroshima bomb. It released about 110 times the energy of a magnitude 5.0.

Tectonic setting

140 km

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

Depth: shallow

15 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 100 km

USGS lists 1 M2.5+ earthquake within 100 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.

M3M4M5M61h6h1d3d7d14d30dMainshock M6.4
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 6.650 km NNW of Ambunti, Papua New Guinea92y ago · 70 km NW of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 24 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.8New Guinea, Papua New GuineaSeptember 20, 1935 · 176 km W of this epicenter
  2. 7.650 km N of Wewak, Papua New GuineaJuly 3, 1918 · 163 km NE of this epicenter
  3. 7.593 km SW of Aitape, Papua New GuineaJuly 29, 1917 · 149 km NW of this epicenter
  4. 7.349 km NNE of Angoram, Papua New GuineaMay 7, 1907 · 172 km NE of this epicenter
  5. 7.1132 km NNE of Wewak, Papua New GuineaAugust 26, 1906 · 256 km NE of this epicenter
  6. 7.143 km SW of Aitape, Papua New GuineaAugust 7, 1931 · 148 km NW of this epicenter
  7. 7.165 km ENE of Wewak, Papua New GuineaApril 27, 1909 · 186 km NE of this epicenter
  8. 7.061 km W of Angoram, Papua New GuineaJune 9, 1925 · 76 km NE of this epicenter

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. The most severe:

  1. 1907M7.4

    Bismarck Sea

    15 Dec 1907 · 149 km away

    Moderate damage ($1–5M)tsunami

  2. 1935M7.8

    N-Central

    20 Sep 1935 · 174 km away

    tsunami

  3. 1916M7.5

    N Coast

    3 Aug 1916 · 185 km away

  4. 1917M7.5

    Papua New Guinea

    29 Jul 1917 · 149 km away

    tsunami

  5. 1918M7.5

    N Coast

    3 Jul 1918 · 107 km away

  6. 1931M7.0

    Bismarck Sea

    7 Aug 1931 · 140 km away

    tsunami

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

Nearby trackers

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