Earthquake Swarm S20241026.1: Seismic Activity Near Prague, Oklahoma

An earthquake swarm designated S20241026.1 occurred 8 km northwest of Prague, Oklahoma, between 01:34 on 26 October 2024 and 03:13 on 28 October 2024. Over 49 hours and 38 minutes, 40 events were recorded, with magnitudes ranging from -1.7 to 1.6 and focal depths between 3 km and 7 km. The sequence featured a dense cluster of events on 26 October, particularly between 17:33 and 18:58, followed by sporadic smaller shocks through 28 October.

The swarm exhibited typical characteristics of fluid-induced sequences, with the majority of events below magnitude 0 and only four exceeding magnitude 1.0. The largest event reached magnitude 1.6 at 17:40 on 26 October at 7 km depth. Depths remained consistent in the shallow crustal range, consistent with regional basement-involved faulting.

Central Oklahoma lies within a zone of elevated seismicity linked to the Nemaha Uplift and associated structures such as the Wilzetta Fault. The area features Precambrian basement rocks overlain by Paleozoic sedimentary layers. Since the early 2000s, increased injection of wastewater from oil and gas operations has reactivated pre-existing faults, producing both isolated events and swarm-like clusters.

Historical records indicate nine swarms in the Prague region since 1 January 2000. These occurred in 2011 (one swarm), 2023 (one swarm), and seven swarms in 2024 alone. The 2011 swarm preceded the magnitude 5.7 Prague earthquake of November 2011, which was attributed to nearby disposal wells. The recent acceleration in swarm frequency aligns with ongoing industrial activity in the region.

The October 2024 swarm adds to a pattern of low-magnitude, temporally clustered seismicity that poses minimal surface hazard but provides data for monitoring fault behavior under induced stress conditions. Depths of 3–7 km place events within or just above the crystalline basement, where fluid migration can most effectively influence slip.

Continued seismic monitoring remains essential for distinguishing natural from anthropogenic contributions and for assessing long-term changes in regional strain release.

References
Oklahoma Geological Survey, Earthquake Catalog (2024).
United States Geological Survey, Induced Earthquakes Overview (updated 2024).
National Earthquake Information Center, Regional Seismicity Reports.