Location:

Period:

24 Jun 2020 23:30:47 - 25 Jun 2020 12:47:16 (13 hours 16 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

6 swarms found nearby.

2023

S20230407.1(29.8km)

6 Apr

2 days 16 hours

36 earthquakes

2024

S20240203.2(28.4km)

3 Feb

43 days 4 hours

2981 earthquakes

S20240606.1(29.8km)

5 Jun

36 days 12 hours

573 earthquakes

S20241105.1(29.9km)

5 Nov

6 days 12 hours

76 earthquakes

S20241129.1(30.0km)

28 Nov

6 days 15 hours

139 earthquakes

2025

S20250510.1(28.9km)

9 May

6 days 6 hours

113 earthquakes

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Earthquake Swarm S20200625.1 Near Stroud, Oklahoma

An earthquake swarm designated S20200625.1 was recorded 5 km north of Stroud, Oklahoma, beginning at 23:30 on 24 June 2020 and concluding at 12:47 on 25 June 2020. Over the 13-hour, 16-minute period, 24 events were detected, all of small magnitude and shallow depth consistent with regional patterns of induced seismicity.

The sequence featured events ranging from magnitude 0.2 to 2.1, with focal depths between 5 km and 9 km. The largest event reached magnitude 2.1 at 00:22:30 on 25 June. Multiple events clustered within minutes of one another, including pairs at 00:22 and 00:42, illustrating the typical swarm behavior of numerous similar-sized shocks without a dominant mainshock-aftershock progression. Later activity tapered, with the final recorded event at magnitude 1.4.

Stroud lies within Lincoln County in north-central Oklahoma, a region underlain by Paleozoic sedimentary rocks of the Cherokee Platform overlying Precambrian basement. The area contains numerous faults that can be reactivated by changes in pore pressure. Since the late 2000s, Oklahoma has experienced a marked rise in seismicity linked to wastewater injection associated with oil and gas production, particularly into the Arbuckle Group. Annual earthquake counts in the state peaked above 900 magnitude 3+ events around 2015 before regulatory reductions in injection volumes lowered rates after 2016. Activity near Stroud in 2020 remained within this established framework of induced events at depths of 5–9 km.

Swarm characteristics observed here align with other central Oklahoma sequences, where fluid migration along pre-existing fractures produces tightly clustered, low-magnitude earthquakes over hours to days. Depths reported for the swarm match the typical range for injection-induced events in the region, occurring above the crystalline basement.

No damage or felt reports of significance accompanied this swarm, consistent with its maximum magnitude of 2.1. Continued monitoring by the Oklahoma Geological Survey and USGS remains essential for tracking injection-related activity in the area.

References:
Oklahoma Geological Survey Earthquake Catalog
USGS Earthquake Hazards Program
Ellsworth, W.L. (2013). Injection-induced earthquakes. Science.
Walsh, F.R. & Zoback, M.D. (2015). Oklahoma's recent earthquakes and saltwater disposal. Science Advances.