Seismic Swarm S20240929.1: Analysis of Activity Near Prague, Oklahoma

A seismic swarm designated S20240929.1 was recorded 8 km northwest of Prague, Oklahoma, beginning at 04:18 on 28 September 2024 and concluding at 22:54 on 9 October 2024. Over 282 hours and 35 minutes, the swarm produced 125 earthquakes. Examination of the first 100 events reveals predominantly low-magnitude activity, with values ranging from -1.9 to 1.7. The majority of events clustered between magnitudes -1.5 and 0.5, while depths remained shallow, typically 2 to 7 km and averaging near 5 km. Temporal distribution shows an initial burst of activity on 28 September, followed by sustained but fluctuating rates through early October. Several events occurred in rapid succession, such as pairs within seconds on 28 September at 16:34 and 29 September at 00:51. Depths exhibited minor variation, with a few outliers reaching 10 km on 30 September. This pattern is consistent with fluid-induced seismicity observed in the region. Oklahoma lies within the stable continental interior, underlain by Precambrian basement rocks of the Midcontinent Rift System and overlying Paleozoic sedimentary sequences. The Prague area sits near the Nemaha Uplift and the Wilzetta Fault Zone, where natural seismicity is low but anthropogenic influences have elevated activity since the early 2000s. Wastewater injection from oil and gas operations has been linked to increased pore pressure along pre-existing faults, triggering swarms at depths of 3–7 km. Historical records indicate eight swarms in the vicinity since 1 January 2000. These occurred in 2011 (one swarm), 2023 (one swarm), and 2024 (six swarms). The 2011 swarm preceded the magnitude 5.7 Prague earthquake on 6 November, which caused significant damage and was also attributed to nearby injection wells. Subsequent monitoring has documented episodic swarms with similar magnitude and depth characteristics. The current swarm’s parameters align with prior episodes in the area, reinforcing the role of industrial fluid management in modulating local seismicity. Continued surveillance by regional networks remains essential for assessing any evolution toward larger events.

References

US Geological Survey Earthquake Hazards Program reports on Oklahoma seismicity.
Oklahoma Geological Survey publications on induced earthquakes and fault mapping.
Peer-reviewed studies in the Bulletin of the Seismological Society of America regarding Prague-area swarms.