Seismic Swarm S20241129.1 Near Prague, Oklahoma

Seismic swarm S20241129.1 occurred 8 km northwest of Prague, Oklahoma, from 07:25 on 28 November 2024 to 22:26 on 4 December 2024. The sequence lasted 159 hours and produced 139 earthquakes. Analysis of the first 100 events shows magnitudes ranging from -2.0 to 3.2, with the majority falling between -2.0 and 0.5. Depths clustered between 3 km and 6 km, though a few events reached as shallow as 0 km or as deep as 8 km.

The largest event, magnitude 3.2, took place at 06:14 on 29 November at 6 km depth. Subsequent notable shocks included a magnitude 1.5 at 06:15 the same day and a magnitude 1.4 at 18:01 on 29 November. Most activity consisted of microearthquakes below magnitude 0, consistent with swarm behavior where energy release occurs through numerous small events rather than a single mainshock-aftershock sequence.

Central Oklahoma lies within the stable continental interior, underlain by Precambrian crystalline basement rocks covered by Paleozoic sedimentary layers of the Anadarko Basin. The region features reactivated basement faults associated with the Nemaha Uplift and other structural trends. Seismicity here is frequently linked to fluid injection from oil and gas operations, which can increase pore pressure along pre-existing faults and trigger slip.

Historical records indicate 12 swarms in the Prague area since 1 January 2000. These include single swarms in 2011, 2020, and 2023, followed by a sharp rise to nine swarms in 2024 alone. This recent acceleration aligns with broader patterns of induced seismicity observed across Oklahoma since the mid-2000s, when wastewater disposal volumes increased substantially.

The shallow focal depths recorded during S20241129.1 are typical of injection-related events, which often nucleate within the upper 5–7 km of the crust. Continued monitoring remains important given the elevated swarm frequency observed in 2024.

References

• SeismoSight internal swarm classification data for S20241129.1 and historical counts (2000–2024)
• U.S. Geological Survey earthquake catalog and Oklahoma Geological Survey reports on regional seismicity and fault systems
• Peer-reviewed studies on induced seismicity in the Anadarko Basin and Nemaha Uplift (e.g., publications in Seismological Research Letters, 2015–2023)