Seismic Swarm S20231230.2: Analysis of Activity Near Mentone, Texas

SeismoSight registered Swarm S20231230.2 beginning at 07:58 on 30 December 2023 and concluding at 09:42 on 1 January 2024. The sequence occurred 37 km west-southwest of Mentone, Texas, and comprised 47 earthquakes over 49 hours and 43 minutes. Event depths ranged primarily between 5 km and 9 km, with the majority clustered near 7 km. Magnitudes remained modest, peaking at 3.9.

The sequence initiated with two events of magnitude 1.7 at depths of 6 km and 5 km. Activity intensified later on 30 December, including a magnitude 3.3 at 18:42, a magnitude 3.1 at 18:54, and the largest event of magnitude 3.9 at 19:32, all near 7 km depth. Additional notable shocks included a magnitude 3.5 at 20:28 and a magnitude 3.2 at 21:50, both at 7 km. Subsequent events through 31 December and into 1 January showed declining frequency and lower magnitudes, mostly between 1.5 and 2.5, with depths remaining in the 5–8 km range.

This swarm exhibits classic characteristics of clustered, shallow crustal seismicity. Depths concentrated around 7 km suggest activation along pre-existing faults within the sedimentary sequence. The rapid succession of events on the first day, followed by a gradual decay, aligns with patterns observed in fluid-induced sequences where pore-pressure changes trigger slip on favorably oriented structures.

The location lies within the Delaware Basin, a western subdivision of the larger Permian Basin in West Texas. This province features thick accumulations of Paleozoic sedimentary rocks overlying Precambrian basement. Regional tectonics reflect a stable intraplate setting with minimal natural seismicity prior to extensive hydrocarbon development. Since the early 2000s, however, the basin has experienced elevated earthquake rates correlated with wastewater injection from oil and gas operations.

Historical records indicate ten swarms in the broader area since 1 January 2000. One occurred in 2022 and nine in 2023, underscoring an increasing frequency of swarm-type activity. Depths and magnitudes recorded in Swarm S20231230.2 remain consistent with these prior episodes, reinforcing the interpretation of anthropogenic triggering in a region of heightened fluid pressures.

Continued monitoring is essential given the basin’s ongoing production activities. Integration of seismic data with injection records can improve understanding of causative mechanisms and support mitigation strategies.

References

• United States Geological Survey Earthquake Catalog (earthquake.usgs.gov)
• Texas Bureau of Economic Geology, Permian Basin Studies
• SeismoSight internal swarm classification records