Location:

Period:

23 Nov 2002 13:26:01 - 10 Dec 2002 07:29:49 (16 days 18 hours 3 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

425

21 swarms found nearby.

2002

S20021103.1(19.5km)

2 Nov

123 days 19 hours

7093 earthquakes

S20021104.2(28.2km)

3 Nov

19 days 3 hours

621 earthquakes

S20021108.1(25.6km)

7 Nov

1 day 2 hours

42 earthquakes

S20021111.1(16.0km)

10 Nov

1 day 16 hours

49 earthquakes

S20021125.1(14.9km)

24 Nov

3 days 20 hours

81 earthquakes

S20021126.1(19.3km)

25 Nov

1 day 2 hours

30 earthquakes

S20021201.1(16.9km)

30 Nov

6 days 3 hours

158 earthquakes

S20021207.1(13.6km)

6 Dec

20 days 21 hours

548 earthquakes

S20021211.1(14.9km)

10 Dec

4 days 4 hours

122 earthquakes

S20021218.1(14.6km)

18 Dec

1 day 16 hours

36 earthquakes

S20021220.2(14.5km)

20 Dec

3 days 6 hours

135 earthquakes

S20021229.1(18.1km)

28 Dec

9 days 5 hours

191 earthquakes

2003

S20030101.1(20.2km)

1 Jan

2 days 1 hours

49 earthquakes

S20030112.1(12.5km)

11 Jan

2 days 21 hours

45 earthquakes

S20030203.1(14.6km)

2 Feb

3 days 0 hours

42 earthquakes

S20030223.2(16.8km)

22 Feb

1 day 14 hours

31 earthquakes

S20030316.1(14.7km)

15 Mar

1 day 20 hours

37 earthquakes

S20030910.1(8.3km)

9 Sep

2 days 8 hours

35 earthquakes

S20031210.1(3.0km)

9 Dec

10 days 20 hours

147 earthquakes

2004

S20040129.1(4.3km)

28 Jan

3 days 8 hours

47 earthquakes

2006

S20061005.1(7.0km)

4 Oct

16 hours

26 earthquakes

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Seismic Swarm S20021124.1: Analysis of Activity near Paxson, Alaska

Seismic swarm S20021124.1 was recorded 87 km west-northwest of Paxson, Alaska, beginning at 13:26 on 23 November 2002 and concluding at 07:29 on 10 December 2002. Over 402 hours and 3 minutes, the swarm comprised 425 earthquakes. This sequence occurred in a tectonically active portion of the eastern Alaska Range, providing valuable data on localized crustal response.

Analysis of the first 100 events reveals predominantly shallow focal depths, with most occurring between 0 and 21 km. Magnitudes ranged from 0.6 to 2.7, indicating low-energy release consistent with swarm behavior rather than a mainshock-aftershock sequence. Early events on 23 November included magnitudes of 1.9 at 3 km depth and 2.7 at 8 km depth. Subsequent activity through 26 November showed a mix of events clustered at depths under 10 km, interspersed with slightly deeper occurrences up to 21 km. This distribution suggests fluid migration or stress adjustments within the upper crust as contributing mechanisms.

The swarm's location places it within the influence of the Denali Fault system, a major right-lateral strike-slip structure extending across central Alaska. The region experiences ongoing deformation from Pacific-North American plate interaction, where the Pacific Plate subducts beneath the North American Plate at the Alaska-Aleutian megathrust to the south. This tectonic regime produces frequent seismicity, including both subduction-related and intraplate crustal events along the Denali Fault.

Historical context highlights the area's seismic productivity. The first of four swarms recorded since 2000 occurred in 2002, underscoring episodic clustering in this segment of the fault zone. The timing of S20021124.1 followed the magnitude 7.9 Denali earthquake of 3 November 2002 by approximately three weeks, consistent with patterns of triggered or secondary seismic activity along the broader fault network.

Such swarms contribute to understanding stress transfer and fault segmentation in south-central Alaska. Continued monitoring supports refined hazard assessments for infrastructure and communities in the region, where the Denali Fault remains capable of producing large-magnitude events.

References

USGS Earthquake Catalog (data source for swarm parameters)
Alaska Earthquake Center regional reports on Denali Fault tectonics