Location:

Period:

10 Nov 2002 01:15:25 - 13 Nov 2002 10:06:51 (3 days 8 hours 51 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

4 swarms found nearby.

2002

PS20021103.1(56.8km)

3 Nov

6 hours

10 earthquakes

S20021104.4(8.2km)

3 Nov

92 days 10 hours

2412 earthquakes

S20021104.6(23.3km)

3 Nov

11 days 17 hours

142 earthquakes

2012

S20120807.1(16.6km)

7 Aug

1 day 12 hours

48 earthquakes

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Seismic Swarm S20021110.2: Analysis of Activity Near Paxson, Alaska

Seismic swarm S20021110.2 was recorded 20 km NNE of Paxson, Alaska, from 01:15 on 10 November 2002 to 10:06 on 13 November 2002. Over this 80-hour, 51-minute period, 49 earthquakes occurred, with magnitudes ranging from 0.7 to 3.3 and focal depths primarily between 0 and 13 km. The events clustered in the hours immediately following the 3 November 2002 magnitude-7.9 Denali Fault earthquake, suggesting a possible link to regional stress redistribution.

The swarm exhibited typical characteristics of aftershock-like sequences, with the largest events including a magnitude-3.2 quake at 03:05 on 10 November (depth 1 km) and a magnitude-3.3 event at 06:43 on 12 November (depth 4 km). Other notable shocks reached magnitude 2.8 on 12 and 13 November. Depths remained shallow throughout, consistent with activity along upper-crustal structures. Activity peaked early on 10 November before gradually declining, with the final event recorded at magnitude 1.2 on 13 November.

This swarm marked the first of three documented swarms in the region since 1 January 2000. Its timing, one week after the Denali Fault mainshock, aligns with patterns of triggered seismicity observed along strike-slip systems. The location lies within the central Alaska Range, where the Denali Fault accommodates right-lateral motion between the Pacific and North American plates.

Central Alaska experiences high seismicity due to ongoing convergence and transform tectonics. The Denali Fault forms a major intracontinental strike-slip boundary that last produced a great earthquake in 2002, with surface rupture extending more than 340 km. Shallow crustal earthquakes in this area commonly occur at depths less than 15 km, reflecting brittle failure within the upper plate. Historical records show recurrent moderate swarms near the fault trace, often associated with post-mainshock relaxation or fluid migration.

No significant surface deformation or damage was reported from swarm S20021110.2, consistent with its modest magnitudes. Continued monitoring of such sequences provides valuable data on fault-zone behavior following large events.

References

USGS Earthquake Catalog
Alaska Earthquake Center, University of Alaska Fairbanks
SeismoSight internal swarm classification records