Location:

150 km SE of Petropavlovsk-Kamchatsky, Russia

Period:

20 Jul 2025 13:54:31 - 22 Jul 2025 22:22:49 (2 days 8 hours 28 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

17 swarms found nearby.

2001

PS20011008.1(45.4km)

7 Oct

1 day 4 hours

6 earthquakes

2013

PS20130519.1(34.2km)

18 May

2 days 16 hours

33 earthquakes

S20130519.1(27.9km)

19 May

2 days 7 hours

43 earthquakes

2024

PS20240817.1(80.6km)

17 Aug

3 hours

5 earthquakes

2025

PS20250720.1(50.4km)

20 Jul

2 days 17 hours

44 earthquakes

PS20250730.3(8.9km)

29 Jul

2 days 23 hours

69 earthquakes

PS20250730.5(43.8km)

30 Jul

2 days 11 hours

12 earthquakes

PS20250803.2(31.0km)

3 Aug

13 hours

8 earthquakes

PS20250806.1(93.9km)

5 Aug

1 day 11 hours

7 earthquakes

PS20250824.1(17.6km)

23 Aug

23 hours

5 earthquakes

PS20250911.1(102.0km)

10 Sep

16 hours

6 earthquakes

PS20250918.1(42.4km)

18 Sep

2 days 8 hours

36 earthquakes

PS20250922.1(108.9km)

22 Sep

2 hours

5 earthquakes

PS20251003.1(86.2km)

3 Oct

14 hours

6 earthquakes

PS20251005.1(108.2km)

4 Oct

22 hours

5 earthquakes

PS20251103.1(25.9km)

3 Nov

1 day 16 hours

15 earthquakes

2026

PS20260619.1(60.1km)

19 Jun

20 hours

7 earthquakes

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Seismic Swarm Activity Southeast of Petropavlovsk-Kamchatsky, July 2025

Seismic swarm S20250721.1 was recorded 150 km southeast of Petropavlovsk-Kamchatsky on Russia’s Kamchatka Peninsula. The sequence began at 13:54 on 20 July 2025 and concluded at 22:22 on 22 July 2025, spanning 56 hours and 28 minutes. During this interval, 39 earthquakes were registered, with magnitudes ranging from 4.1 to 4.9 and focal depths between 9 km and 45 km.

The swarm exhibited two main phases of elevated activity. The first phase on 20 July featured eight events, including two magnitude-4.7 shocks at 10 km depth. The second phase, concentrated on 21 July, produced the majority of events, with five earthquakes reaching magnitude 4.8–4.9. Notable events included a magnitude-4.9 shock at 25 km depth at 08:42 and another at 34 km depth at 12:43. Activity tapered on 22 July, ending with a magnitude-4.5 event at 10 km depth.

Kamchatka lies within the Pacific Ring of Fire at the convergent boundary where the Pacific Plate subducts beneath the Okhotsk Plate. This tectonic setting generates frequent seismic swarms as fluids and stress changes trigger clustered fault slip at shallow to intermediate depths. The region’s crust accommodates both megathrust events and smaller swarm sequences linked to volcanic and hydrothermal systems.

Since 2000, five swarms have been documented in the broader area. Earlier episodes occurred in 2001 (one swarm), 2013 (two swarms), and 2024 (one swarm), with the current 2025 sequence representing the fifth. These recurrent swarms reflect ongoing plate-boundary strain accumulation and release.

The July 2025 swarm remained within typical magnitude and depth ranges observed in prior Kamchatka sequences. No larger mainshock followed, consistent with swarm behavior driven by distributed crustal adjustments rather than a single fault rupture.

References
SeismoSight internal classification data for swarm S20250721.1.
USGS Earthquake Hazards Program regional tectonic summaries for the Kamchatka Peninsula.
Global Volcanism Program background on Kamchatka subduction-zone seismicity.