Location:

Period:

3 Sep 2010 16:35:47 - 4 Sep 2010 04:55:56 (12 hours 20 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 7.0; 19 km NE of Methven, New Zealand; (3 Sep 2010) (15km from the swarm center)

4 swarms found nearby.

2010

S20100904.1(35.3km)

3 Sep

2 days 18 hours

47 earthquakes

2011

S20110222.1(54.5km)

21 Feb

2 days 16 hours

48 earthquakes

PS20111223.1(66.2km)

23 Dec

1 hours

5 earthquakes

S20111223.1(65.9km)

23 Dec

1 day 6 hours

25 earthquakes

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Seismic Swarm PS20100904.1: Darfield Region, New Zealand

A seismic swarm designated PS20100904.1 occurred near Darfield, New Zealand, from 16:35 on 3 September 2010 to 04:55 on 4 September 2010. Over this 12-hour, 20-minute period, five earthquakes were recorded at a location 12 km south-southwest of Darfield.

The sequence began with a magnitude 7.0 event at 16:35:47 on 3 September at a depth of 12 km. This was followed by a magnitude 5.0 quake at 16:52:55 (depth 10 km) and a magnitude 5.1 event at 16:59:19 (depth 10 km). Activity continued into the next day with a magnitude 3.9 shock at 04:33:43 (depth 1 km) and a magnitude 5.0 event at 04:55:56 (depth 5 km).

This swarm is situated within the Canterbury Plains, a region underlain by Quaternary alluvial sediments overlying Mesozoic basement rocks of the Torlesse Supergroup. The area lies near the Pacific-Australian plate boundary, where oblique convergence drives active deformation across a network of strike-slip and reverse faults. The September 2010 activity aligns with the initiation of the Darfield earthquake sequence, which released strain along previously unrecognized fault segments in the eastern South Island.

Geological records indicate that the Canterbury region has experienced recurrent seismic events throughout the Holocene, shaped by the broader tectonic regime of the Pacific Ring of Fire. The 2010 swarm preceded and contributed to subsequent aftershock patterns that affected the Christchurch urban area in 2011. Depths ranging from 1 km to 12 km reflect rupture within the shallow crust, typical of the region's thin sedimentary cover and underlying indurated greywacke.

The proximity of the swarm center to a magnitude 7.0 mainshock located 19 km northeast of Methven underscores the spatial clustering characteristic of Canterbury seismicity. Such events highlight the distributed nature of faulting across the plains, where blind thrusts and strike-slip structures accommodate regional strain without prominent surface expression prior to rupture.

References

SeismoSight internal swarm classification PS20100904.1
GNS Science New Zealand earthquake catalogue (2010 events)
Geological Survey of New Zealand regional tectonic summaries