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Location:
5 km E of Hebgen Lake Estates, Montana
Period:
25 Oct 2000 01:50:49 - 27 Oct 2000 17:21:01 (2 days 15 hours 30 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
52
81 swarms found nearby.
2000
S20000125.1(12.0km)
25 Jan
1 day 8 hours
67 earthquakes
29 Mar
9 days 3 hours
185 earthquakes
8 Apr
1 day 23 hours
41 earthquakes
S20000728.1(28.1km)
27 Jul
5 days 11 hours
144 earthquakes
S20001124.1(27.7km)
23 Nov
3 days 8 hours
120 earthquakes
S20001224.1(23.1km)
23 Dec
4 days 11 hours
64 earthquakes
2001
S20010119.1(14.4km)
18 Jan
4 days 18 hours
341 earthquakes
S20010227.1(11.0km)
26 Feb
2 days 5 hours
56 earthquakes
2 Dec
5 days 0 hours
131 earthquakes
8 Dec
19 days 5 hours
335 earthquakes
2002
S20020130.2(14.1km)
30 Jan
2 days 22 hours
52 earthquakes
S20021104.1(16.1km)
3 Nov
4 days 4 hours
118 earthquakes
3 Nov
3 days 12 hours
80 earthquakes
S20021205.1(14.5km)
5 Dec
2 days 12 hours
405 earthquakes
S20021214.1(11.2km)
13 Dec
1 day 12 hours
26 earthquakes
2003
S20030103.2(26.5km)
3 Jan
4 days 3 hours
75 earthquakes
S20030131.1(27.6km)
31 Jan
1 day 15 hours
36 earthquakes
5 Feb
1 day 18 hours
42 earthquakes
2004
S20040413.1(15.1km)
13 Apr
6 days 22 hours
457 earthquakes
16 Jul
1 day 16 hours
38 earthquakes
2005
3 Jun
2 days 8 hours
49 earthquakes
2006
S20060222.1(29.2km)
22 Feb
15 hours
44 earthquakes
S20060613.1(26.0km)
12 Jun
1 day 14 hours
45 earthquakes
18 Jun
1 day 11 hours
57 earthquakes
S20061015.1(29.1km)
14 Oct
19 hours
79 earthquakes
2007
S20070620.1(25.6km)
20 Jun
1 hours
26 earthquakes
14 Dec
22 hours
28 earthquakes
S20071231.1(15.8km)
30 Dec
3 days 10 hours
61 earthquakes
2008
S20080109.1(15.0km)
9 Jan
4 days 20 hours
89 earthquakes
S20080203.1(25.9km)
3 Feb
21 hours
47 earthquakes
S20080311.1(29.9km)
11 Mar
2 days 13 hours
69 earthquakes
S20080729.1(26.7km)
28 Jul
4 days 18 hours
189 earthquakes
S20080807.1(22.3km)
7 Aug
6 hours
32 earthquakes
3 Dec
6 days 17 hours
213 earthquakes
2009
16 Apr
5 days 18 hours
136 earthquakes
S20090630.1(27.0km)
30 Jun
1 day 12 hours
34 earthquakes
12 Sep
21 hours
24 earthquakes
16 Sep
1 day 7 hours
28 earthquakes
2010
S20100117.1(24.8km)
16 Jan
19 days 8 hours
2268 earthquakes
2011
3 May
1 day 22 hours
33 earthquakes
2013
S20130507.1(23.9km)
7 May
22 hours
34 earthquakes
29 Jun
3 days 16 hours
79 earthquakes
S20130713.1(16.5km)
13 Jul
19 hours
30 earthquakes
27 Sep
1 day 12 hours
28 earthquakes
23 Nov
6 days 16 hours
223 earthquakes
2014
S20140122.1(24.8km)
21 Jan
2 days 1 hours
46 earthquakes
S20140601.1(29.6km)
31 May
6 days 5 hours
232 earthquakes
18 Aug
1 day 15 hours
42 earthquakes
20 Aug
1 day 4 hours
40 earthquakes
2015
21 Jan
1 day 8 hours
135 earthquakes
13 Oct
1 day 20 hours
31 earthquakes
7 Nov
1 day 23 hours
85 earthquakes
2016
24 Sep
1 day 16 hours
46 earthquakes
2017
12 Jun
45 days 12 hours
1542 earthquakes
1 Aug
17 days 7 hours
784 earthquakes
20 Aug
4 days 18 hours
43 earthquakes
27 Aug
3 days 8 hours
66 earthquakes
2018
S20180216.1(11.8km)
15 Feb
11 days 1 hours
728 earthquakes
S20180725.1(27.4km)
24 Jul
2 days 20 hours
52 earthquakes
2019
S20190326.2(25.8km)
26 Mar
20 hours
29 earthquakes
S20191026.1(26.0km)
26 Oct
1 day 22 hours
83 earthquakes
2020
S20200219.1(27.0km)
18 Feb
2 days 20 hours
62 earthquakes
S20200509.3(11.2km)
9 May
2 days 5 hours
80 earthquakes
S20200522.1(25.8km)
22 May
2 hours
36 earthquakes
S20200529.1(26.5km)
29 May
1 day 10 hours
88 earthquakes
2021
27 Jun
5 days 17 hours
230 earthquakes
2022
S20220329.1(17.0km)
28 Mar
2 days 12 hours
117 earthquakes
S20220611.1(26.6km)
10 Jun
2 days 20 hours
62 earthquakes
S20220826.1(25.7km)
26 Aug
9 days 4 hours
198 earthquakes
S20220918.2(25.6km)
17 Sep
6 days 20 hours
389 earthquakes
S20220930.1(26.7km)
29 Sep
3 days 4 hours
53 earthquakes
S20221013.1(25.9km)
13 Oct
8 days 6 hours
111 earthquakes
S20221115.1(27.0km)
14 Nov
2 days 5 hours
48 earthquakes
2023
S20230207.2(15.7km)
6 Feb
2 days 9 hours
63 earthquakes
13 Mar
1 day 18 hours
136 earthquakes
S20231004.1(26.8km)
3 Oct
1 day 14 hours
39 earthquakes
2024
S20240106.1(15.4km)
6 Jan
10 hours
35 earthquakes
S20240218.1(27.2km)
18 Feb
9 hours
50 earthquakes
23 Apr
4 days 7 hours
79 earthquakes
2025
4 Mar
12 hours
25 earthquakes
7 May
8 hours
37 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20001025.1: Analysis of Activity Near Hebgen Lake, Montana

Seismic swarm S20001025.1 occurred in the Hebgen Lake region of southwestern Montana, beginning at 01:50 on 25 October 2000 and concluding at 17:21 on 27 October 2000. The sequence lasted 63 hours and 30 minutes, during which 52 earthquakes were recorded approximately 5 km east of Hebgen Lake Estates. Magnitudes ranged from -9.9 to 2.1, with the majority of events clustered between 10 and 13 km depth, indicating shallow crustal activity typical of the Intermountain Seismic Belt.

This swarm exemplifies a classic earthquake sequence lacking a dominant mainshock, instead featuring numerous small events distributed over time. Such patterns often reflect localized stress adjustments along existing faults or minor fluid migration within the crust. Depths remained consistent near 11–12 km for most events, with isolated shallower occurrences around 5–8 km and a few deeper readings near 14 km. The temporal distribution showed peak activity during the first day, tapering gradually over the following 48 hours.

The Hebgen Lake area lies within the tectonically active Basin and Range province, where extensional forces drive normal faulting. The region experienced the devastating 1959 Hebgen Lake earthquake (magnitude 7.3), which ruptured the Hebgen Lake fault and triggered a massive landslide that formed Earthquake Lake. Ongoing microseismicity underscores the persistent strain accumulation along these structures, influenced by proximity to the Yellowstone volcanic system approximately 50 km to the east.

Historical records indicate that four swarms have occurred in the area since 1 January 2000, with S20001025.1 representing the earliest documented cluster. Subsequent swarms followed similar patterns of low-magnitude, high-frequency events, reinforcing the characterization of the Hebgen Lake fault zone as prone to episodic swarm behavior rather than isolated large shocks.

Monitoring data from this swarm contribute to improved understanding of precursory signals and fault mechanics in the northern Intermountain region. Continued observation supports regional hazard assessments, as even minor swarms can delineate active fault segments capable of producing larger events.

References

USGS Earthquake Hazards Program – Hebgen Lake, MT historical seismicity
Montana Bureau of Mines and Geology – Regional fault mapping
SeismoSight internal swarm classification database