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Location:
239 km SSW of Prince Rupert, Canada
Period:
28 Oct 2012 03:04:08 - 29 Oct 2012 11:07:15 (1 day 8 hours 3 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
23
M 7.0+:
M 7.8; 206 km SW of Prince Rupert, Canada; (28 Oct 2012) (66km from the swarm center)
3 swarms found nearby.
2008
PS20080105.1(98.5km)
5 Jan
13 hours
6 earthquakes
2012
PS20121030.1(23.3km)
30 Oct
11 hours
5 earthquakes
2013
PS20130904.1(158.5km)
3 Sep
4 hours
5 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm PS20121028.1: Analysis of Events Near Prince Rupert, Canada

A seismic swarm designated PS20121028.1 was recorded in the region 239 km SSW of Prince Rupert, British Columbia. The sequence began at 03:04 on 28 October 2012 and concluded at 11:07 on 29 October 2012, spanning 32 hours and 3 minutes. During this period, 23 earthquakes were registered.

The swarm featured a mainshock of magnitude 7.8 at a depth of 14 km on 28 October 2012 at 03:04:08. Subsequent events included multiple magnitude 5+ earthquakes clustered in the initial hours. Notable shocks occurred at 03:14:10 (M5.8, 10 km depth), 03:52:20 (M5.5, 10 km), 04:25:25 (M5.4, 2 km), 18:54:20 (M6.3, 9 km), and 19:09:53 (M5.6, 10 km). Later activity tapered with events such as M5.0 at 01:49:01 on 29 October and a final M5.0 at 11:07:15. Depths ranged primarily between 2 km and 25 km, with the majority at or near 10 km.

Historical records indicate this was the sole swarm in the area since 1 January 2000. The previous swarm occurred in 2008. A strong earthquake of magnitude 7.8 took place on 28 October 2012, 206 km southwest of Prince Rupert and 66 km from the swarm center.

The Prince Rupert region lies within the tectonically active Pacific-North American plate boundary along the western margin of British Columbia. This zone encompasses the Queen Charlotte Fault system, a major transform boundary characterized by right-lateral strike-slip motion, with segments exhibiting thrust components due to oblique convergence. The Haida Gwaii offshore area, adjacent to the swarm location, has a documented history of large-magnitude events driven by these plate interactions. Crustal stresses accumulate rapidly, resulting in both strike-slip and thrust faulting at shallow to intermediate depths.

Seismic activity in this setting reflects ongoing subduction-related dynamics and transform faulting, with the 2012 sequence aligning with patterns of clustered aftershocks following a primary rupture. Depths recorded in the swarm are consistent with crustal faulting in the overriding North American plate and along the plate interface.

References

SeismoSight internal classification data for swarm PS20121028.1.
Geological Survey of Canada reports on regional tectonics and the Queen Charlotte Fault.
Natural Resources Canada earthquake database for events since 2000.