QuakeScout
Magnitude7.1

Reviewed by USGSPapua New Guinea96y ago

M7.1 earthquake 43 km SW of Aitape, Papua New Guinea

Friday, August 7, 1931, 02:11:43 UTC · 3.366°S, 142.031°E

A magnitude 7.1 earthquake struck 43 km SW of Aitape, Papua New Guinea on Friday, August 7, 1931, 02:11:43 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.6 on July 3, 1918.

Magnitude
7.1
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 earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

629 kilotons of TNT

That is about 42 times the Hiroshima bomb. It released about 1,318 times the energy of a magnitude 5.0.

Tectonic setting

77 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 has not published any M2.5+ earthquake within 200 km in the 30 days after this event.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 31 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.650 km N of Wewak, Papua New GuineaJuly 3, 1918 · 174 km E of this epicenter
  2. 7.593 km SW of Aitape, Papua New GuineaJuly 29, 1917 · 50 km SW of this epicenter
  3. 7.349 km NNE of Angoram, Papua New GuineaMay 7, 1907 · 247 km E of this epicenter
  4. 7.1132 km NNE of Wewak, Papua New GuineaAugust 26, 1906 · 259 km E of this epicenter
  5. 7.165 km ENE of Wewak, Papua New GuineaApril 27, 1909 · 238 km E of this epicenter
  6. 7.061 km W of Angoram, Papua New GuineaJune 9, 1925 · 185 km SE of this epicenter
  7. 7.042 km ESE of Wewak, Papua New GuineaMay 13, 1920 · 221 km E of this epicenter
  8. 7.073 km ENE of Vanimo, Papua New GuineaDecember 15, 1907 · 109 km N 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, which together caused about 5 recorded deaths. The most severe:

  1. 1900M6.9

    Nw. Irian Jaya

    7 Oct 1900 · 236 km away

    5 deathsLimited damage (under $1M)tsunami

  2. 1907M7.4

    Bismarck Sea

    15 Dec 1907 · 60 km away

    Moderate damage ($1–5M)tsunami

  3. 1919

    Irian Jaya Region

    21 Nov 1919 · 169 km away · intensity VIII

    Limited damage (under $1M)tsunami

  4. 1916M7.5

    N Coast

    3 Aug 1916 · 283 km away

  5. 1917M7.5

    Papua New Guinea

    29 Jul 1917 · 50 km away

    tsunami

  6. 1918M7.5

    N Coast

    3 Jul 1918 · 54 km away

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

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