Seismic Swarm S20241105.1: Analysis of Recent Activity Near Prague, Oklahoma

Seismic swarm S20241105.1 was recorded northwest of Prague, Oklahoma, beginning at 08:18 on 5 November 2024 and concluding at 20:49 on 11 November 2024. Over this 156-hour and 31-minute period, a total of 76 earthquakes were detected at a location 8 km northwest of the town. This event contributes to the documented history of swarm activity in the region, where 11 such sequences have occurred since 1 January 2000. Prior swarms took place in 2011 (one event), 2020 (one event), 2023 (one event), and 2024 (eight events).

The Prague area sits within central Oklahoma's stable cratonic interior, underlain by Precambrian basement rocks of the Southern Oklahoma Aulacogen and intersected by ancient fault systems such as the Wilzetta Fault. While natural seismicity remains low, the region has experienced elevated earthquake rates since the early 2000s, largely linked to wastewater injection associated with oil and gas production. Depths of the recent swarm events clustered predominantly between 2 km and 6 km, consistent with shallow crustal activity influenced by fluid migration along pre-existing faults.

Magnitudes during the swarm ranged from a low of -1.8 to a high of 1.8, with the majority falling below 0.0. The sequence began with a 1.8 event at 5 km depth on 5 November at 08:18:18 UTC, followed rapidly by numerous smaller events, many at 4–5 km depth. Activity persisted with intermittent peaks, including a 1.6 event at 6 km on 5 November at 22:29:57 and a 1.3 event at 6 km on 11 November at 17:22:38. Negative magnitudes dominated the later stages, reflecting the microseismic character typical of fluid-induced swarms.

This swarm aligns with patterns observed in previous Oklahoma sequences, where clustered events of low to moderate magnitude occur over days to weeks without a single dominant mainshock. Depths remained shallow throughout, rarely exceeding 6 km, supporting interpretations of injection-related triggering rather than deeper tectonic sources. The 2024 swarm count underscores an ongoing trend of increased swarm frequency in the area.

Geological monitoring in central Oklahoma continues to highlight the interplay between anthropogenic factors and the region's fault network. Continued observation of such sequences aids in refining models of induced seismicity and supports hazard assessment for nearby communities.

References
SeismoSight internal swarm classification data for S20241105.1.
USGS Earthquake Catalog (historical Oklahoma seismicity records).
Oklahoma Geological Survey reports on regional tectonics and induced seismicity.