Seismic Swarm S20240606.1 Near Prague, Oklahoma

A seismic swarm designated S20240606.1 was recorded 8 km west-northwest of Prague, Oklahoma, beginning at 14:07 on 5 June 2024 and concluding at 03:03 on 12 July 2024. Over 876 hours and 55 minutes, the sequence produced 573 earthquakes. Analysis of the first 100 events reveals predominantly microseismic activity with magnitudes ranging from -1.9 to 1.4 and focal depths between 0 and 6 km. The initial event measured magnitude 1.0 at 5 km depth, followed by numerous events below magnitude 0.0, indicating low-energy releases typical of fluid-induced sequences.

The Prague region lies within the stable continental interior of the North American craton, underlain by Precambrian basement rocks overlain by Paleozoic sedimentary strata of the Anadarko Basin and adjacent platforms. Ancient fault systems, including segments of the Wilzetta Fault zone, trend through the area and have been reactivated by anthropogenic processes. Since the early 2000s, central Oklahoma has experienced elevated seismicity linked to wastewater injection associated with oil and gas production. These operations increase pore pressure along pre-existing faults, reducing frictional resistance and triggering slip at depths of 3–6 km, consistent with the observed swarm hypocenters.

Historical records indicate six swarms in the vicinity since 1 January 2000, occurring in 2011, 2020, 2023, and three instances in 2024. The 2011 event cluster preceded the magnitude 5.7 Prague earthquake, which caused surface damage and was also attributed to injection-induced triggering. Subsequent swarms have remained smaller in maximum magnitude yet demonstrate recurring activation of the same fault network.

The temporal distribution of the first 100 events shows clustering within the initial days, with a notable increase in event rate on 9 June 2024. Depths cluster around 4–5 km, with occasional shallower (2 km) or deeper (6 km) outliers. Magnitudes exhibit a typical swarm pattern: an initial moderate event followed by a prolonged sequence of smaller aftershocks without a dominant mainshock. No events exceeded magnitude 2.0 in this subset, suggesting limited energy accumulation.

This swarm aligns with broader patterns of induced seismicity documented across the central United States. Ongoing monitoring by regional networks continues to track such sequences to refine hazard assessments and inform regulatory practices regarding injection volumes and well placement.

References

Oklahoma Geological Survey earthquake catalog and swarm reports (2024).
U.S. Geological Survey Earthquake Hazards Program regional seismicity data.
Peer-reviewed studies on induced seismicity in Oklahoma (e.g., Walsh and Zoback, 2015; Schoenball and Ellsworth, 2017).