Location:

Period:

13 Nov 2016 11:02:56 - 15 Nov 2016 06:30:30 (1 day 19 hours 27 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 7.8; 53 km NNE of Amberley, New Zealand; (13 Nov 2016) (92km from the swarm center)

4 swarms found nearby.

2011

PS20111223.1(165.9km)

23 Dec

1 hours

5 earthquakes

2013

S20130721.1(69.5km)

20 Jul

2 days 6 hours

46 earthquakes

PS20130816.1(66.6km)

16 Aug

4 hours

10 earthquakes

2016

S20161113.1(65.5km)

13 Nov

2 days 16 hours

59 earthquakes

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Seismic Swarm PS20161113.1 in the Amberley Region, New Zealand

Seismic swarm PS20161113.1 was recorded in the South Island of New Zealand, centered 53 km NNE of Amberley. The sequence began at 11:02 on 13 November 2016 and concluded at 06:30 on 15 November 2016, spanning 43 hours and 27 minutes. During this period, 33 earthquakes were registered, providing a detailed record of clustered seismic activity in a tectonically dynamic area.

The swarm opened with a magnitude 7.8 event at a depth of 15 km. Subsequent activity included multiple events exceeding magnitude 5.0, such as a 6.5 quake at 11:32 on 13 November at 10 km depth and another 6.5 at 00:34 on 14 November at 9 km depth. Other notable shocks reached magnitudes of 6.2, 6.1, and 5.8, with depths ranging primarily between 7 km and 20 km. The sequence featured a dense cluster of aftershocks on 13 November, followed by continued but diminishing activity through 15 November.

This swarm occurred within New Zealand’s South Island, where the Pacific and Australian plates converge along the Alpine Fault and the Marlborough Fault System. The region experiences ongoing deformation due to oblique subduction and strike-slip faulting, resulting in frequent moderate to large earthquakes. Depths recorded in the swarm align with typical crustal seismicity in this setting, where brittle failure occurs in the upper 20 km of the lithosphere.

Historical data indicate that three swarms have occurred in the area since 1 January 2000. Prior events were limited, with one swarm in 2011 and two in 2013. The 2016 sequence stands out as the most energetic, coinciding with the strongest earthquake (magnitude 7.8) recorded in the region since 2000, located 92 km from the swarm center.

The provided event timings and magnitudes illustrate a classic swarm pattern: an initial large shock followed by a rapid succession of aftershocks that gradually decrease in frequency. Depths remained shallow throughout, consistent with faulting in the upper crust of the Marlborough system.

References

SeismoSight internal classification records for swarm PS20161113.1.
Geological Survey of New Zealand regional tectonic summaries.