Location:

Period:

5 Aug 2007 16:19:37 - 6 Aug 2007 07:47:45 (15 hours 28 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

7 swarms found nearby.

2001

PS20011007.1(164.6km)

7 Oct

5 hours

5 earthquakes

2002

PS20020908.1(183.1km)

8 Sep

11 hours

14 earthquakes

2007

PS20070722.1(19.9km)

22 Jul

4 hours

6 earthquakes

PS20071022.1(19.4km)

22 Oct

6 hours

5 earthquakes

2016

PS20160917.1(138.3km)

17 Sep

1 day 5 hours

6 earthquakes

2023

S20230103.1(105.0km)

2 Jan

3 days 0 hours

47 earthquakes

S20230209.2(113.3km)

8 Feb

3 days 8 hours

50 earthquakes

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Earthquake Swarm PS20070806.1: Seismic Activity East of Vanimo, Papua New Guinea

An earthquake swarm designated PS20070806.1 occurred approximately 40 km east of Vanimo in Papua New Guinea. The sequence began at 16:19 on 5 August 2007 and concluded at 07:47 on 6 August 2007, spanning 15 hours and 28 minutes. During this period, six earthquakes were recorded, with magnitudes ranging from 4.3 to 5.4 and focal depths between 10 km and 35 km.

The events unfolded as follows. The initial shock at 16:19:37 on 5 August registered magnitude 5.0 at 19 km depth. A second event of magnitude 5.0 followed at 16:43:00 at 10 km depth. At 18:11:59, a magnitude 5.1 earthquake occurred at 35 km depth. Early on 6 August, a magnitude 5.4 event struck at 00:26:35 from 26 km depth. This was followed by a magnitude 4.3 shock at 03:30:43 from 10 km depth. The swarm ended with a magnitude 5.0 event at 07:47:45 from 32 km depth.

Such swarms reflect clustered seismic release without a dominant mainshock-aftershock pattern, often linked to fluid migration or stress adjustments along active faults. In this instance, the events remained moderate in size and produced no reported damage or casualties in the sparsely populated coastal region.

Vanimo lies within the tectonically active northern margin of New Guinea, where convergence between the Australian and Pacific plates drives ongoing deformation. The area forms part of the New Guinea Orogen, characterized by thrust faults, strike-slip systems, and rapid uplift. Seismic activity here frequently occurs at shallow to intermediate depths along the plate boundary and associated structures.

Papua New Guinea ranks among the world's most seismically active nations due to its position at a complex triple junction involving multiple microplates. Historical records document numerous moderate events in the Vanimo vicinity, consistent with the broader pattern of distributed seismicity across the island.

Since 1 January 2000, only three swarms have been identified in the region under the SeismoSight classification system: one each in 2001, 2002, and 2007. This low frequency underscores the episodic nature of swarm activity relative to the steady background of isolated earthquakes.

Geological monitoring in Papua New Guinea benefits from regional networks that track both local swarms and larger events capable of generating tsunamis along the northern coast. Continued observation supports improved understanding of strain accumulation in this convergent margin.

References

SeismoSight internal swarm catalog (PS20070806.1 parameters).
USGS Earthquake Hazards Program regional tectonics summary for Papua New Guinea.
Global CMT catalog for focal mechanism context in the New Guinea region.