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Location:
80 km ESE of McKinley Park, Alaska
Period:
2 Apr 2003 08:31:19 - 25 Apr 2003 13:28:10 (23 days 4 hours 56 minutes)
Volcanoes in 100km radius:
Buzzard Creek(75km)
Earthquakes:
248
17 swarms found nearby.
2002
S20021023.1(24.6km)
23 Oct
12 days 6 hours
727 earthquakes
S20021024.1(25.8km)
23 Oct
10 days 5 hours
183 earthquakes
23 Oct
1 day 18 hours
37 earthquakes
S20021104.2(22.8km)
3 Nov
19 days 3 hours
621 earthquakes
S20021105.2(23.4km)
4 Nov
16 days 23 hours
418 earthquakes
S20021108.1(24.7km)
7 Nov
1 day 2 hours
42 earthquakes
S20021108.2(28.3km)
8 Nov
1 day 9 hours
133 earthquakes
S20021110.1(16.0km)
9 Nov
1 day 17 hours
53 earthquakes
12 Nov
1 day 14 hours
71 earthquakes
S20021118.1(25.3km)
17 Nov
3 days 1 hours
69 earthquakes
S20021225.1(20.1km)
24 Dec
5 days 15 hours
113 earthquakes
S20021227.1(12.3km)
26 Dec
7 days 19 hours
98 earthquakes
2003
6 Jan
4 days 21 hours
72 earthquakes
S20030307.1(12.7km)
6 Mar
26 days 8 hours
396 earthquakes
1 Jun
11 days 13 hours
108 earthquakes
13 Jul
20 days 18 hours
166 earthquakes
7 Aug
6 days 18 hours
95 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Analysis of Seismic Swarm S20030403.1 Near McKinley Park, Alaska

Seismic swarm S20030403.1 was recorded in central Alaska, beginning at 08:31 on 2 April 2003 and concluding at 13:28 on 25 April 2003. The events were located 80 km east-southeast of McKinley Park. Over 556 hours and 56 minutes, a total of 248 earthquakes were registered.

The swarm occurred within the tectonically active zone of interior Alaska, where the Denali Fault accommodates lateral motion between the Pacific and North American plates. This strike-slip system forms part of the broader Pacific Ring of Fire, where oblique convergence drives regional deformation. Shallow crustal earthquakes predominate in this setting, reflecting brittle failure in the upper lithosphere.

Central Alaska has a well-documented history of both large-magnitude events and episodic swarms. The magnitude 7.9 Denali Fault earthquake of November 2002, which ruptured more than 300 km of the fault, remains the most significant recent event and likely influenced subsequent stress conditions. Internal records indicate 14 swarms have occurred in the region since 1 January 2000, including 12 in 2002 and two in 2003.

Examination of the first 100 events reveals predominantly low-magnitude activity. Magnitudes ranged from 0.9 to 3.3, with the majority falling between 1.0 and 2.0. Only one event exceeded magnitude 3. The largest shock, magnitude 3.3, occurred shortly after initiation on 2 April at a depth of 1 km. Depths were consistently shallow, spanning 0 to 18 km and averaging near 4 km, consistent with activity along or adjacent to the Denali Fault zone.

Temporal patterns show clustered occurrences within the first 48 hours, followed by a gradual decline in rate while maintaining similar magnitude and depth distributions. Early events included several above magnitude 2.0, interspersed with numerous smaller shocks. Later events in the initial 100 maintained the same shallow-depth profile, indicating sustained release of strain within a limited crustal volume.

This swarm exemplifies the background seismicity that characterizes the Denali region between major ruptures. Continued monitoring by regional networks supports improved understanding of fault behavior and hazard assessment in central Alaska.

References

USGS Earthquake Catalog
Alaska Earthquake Center, University of Alaska Fairbanks
Denali Fault System tectonic summaries, USGS Professional Papers