Seismic Swarm S20240801.1 Near Prague, Oklahoma

A seismic swarm designated S20240801.1 occurred 9 km west-northwest of Prague in central Oklahoma. The sequence began at 01:01 on 1 August 2024 and concluded at 04:54 on 4 August 2024, spanning 75 hours and 52 minutes. During this interval, 60 earthquakes were recorded, with magnitudes ranging from -1.6 to 1.3 and focal depths between 1 km and 6 km.

The events clustered primarily on 1 and 2 August, with the largest magnitude of 1.3 recorded late on 2 August. Subsequent activity diminished, ending with a single event of magnitude -1.3 on 4 August. Depths averaged near 5 km, consistent with shallow crustal seismicity in the region. Most events registered below magnitude 0, characteristic of microseismicity detectable only by sensitive local networks.

Central Oklahoma lies within the Anadarko Basin, where Precambrian basement rocks are overlain by thick Paleozoic sedimentary sequences. The area features reactivated basement faults associated with the Nemaha Uplift and regional tectonic structures. Historical seismicity in this intraplate setting remained low until the early 2000s, after which earthquake rates increased markedly due to fluid injection practices linked to oil and gas production.

Since 2000, six swarms have been documented near Prague. These include single swarms in 2011 and 2023, followed by four swarms in 2024. The 2011 sequence preceded the magnitude 5.7 Prague earthquake, highlighting the potential for swarm activity to occur on the same fault systems. Depths and magnitudes observed in S20240801.1 align with patterns seen in prior induced sequences in the basin.

The short duration and low magnitudes of S20240801.1 suggest a localized release of strain, possibly triggered by transient changes in pore pressure. Continued monitoring remains essential given the region's history of elevated seismic activity.

References

USGS Earthquake Catalog
Oklahoma Geological Survey Annual Seismicity Reports
SeismoSight Internal Swarm Database