Seismic Swarm S20250531.1: Analysis of Activity Near Whites City, New Mexico

Seismic swarm S20250531.1 occurred 57 km south of Whites City, New Mexico, from 02:23 on 31 May 2025 to 11:10 on 4 June 2025. Over 104 hours and 46 minutes, the swarm produced 74 earthquakes. Magnitudes ranged from 0.1 to 3.6, with focal depths between 3 km and 8 km. The largest events included a magnitude 3.6 earthquake at 5 km depth on 1 June at 09:28:46 and several magnitude 3.2–3.3 shocks clustered on 31 May and 1 June.

The region forms part of the Delaware Basin within the greater Permian Basin. It is underlain by thick Permian-age carbonate and evaporite sequences that host extensive karst systems, including nearby Carlsbad Caverns National Park. Tectonic setting reflects subtle extension linked to the eastern margin of the Rio Grande rift, superimposed on a long history of sedimentary basin subsidence. Modern seismicity in southeastern New Mexico is generally sparse but includes both natural events and those potentially influenced by industrial activity such as wastewater injection associated with oil and gas production.

Historical records maintained by SeismoSight indicate 17 swarms in the area since 1 January 2000. Yearly counts show one swarm in 2022, nine in 2023, six in 2024, and the current event in 2025. These recurrent swarms typically feature low-to-moderate magnitudes, shallow-to-mid crustal depths, and durations of several days, consistent with fluid-driven or triggered mechanisms.

Within swarm S20250531.1, activity began with a magnitude 2.6 event at 5 km depth, followed rapidly by additional events of magnitude 2.4–3.3. Peak productivity occurred late on 31 May and early on 1 June, when multiple magnitude 2.6–3.6 earthquakes were recorded within hours. After 2 June, event rates declined steadily, terminating with a final magnitude 1.8 shock at 8 km depth. Depths remained concentrated between 4 km and 7 km throughout, suggesting a compact source volume.

This distribution of magnitudes and depths aligns with patterns observed in prior regional swarms. The absence of a single dominant mainshock and the presence of numerous events of similar size are characteristic of swarm behavior rather than a classical foreshock–mainshock–aftershock sequence. Depths in the 3–8 km range place the activity within the sedimentary column and uppermost basement, where pore-pressure changes can readily influence fault slip.

Continued monitoring is warranted given the history of swarm recurrence in the Delaware Basin. Integration of seismic data with local oil-field operations records may help distinguish natural from induced contributions in future events.

References

• SeismoSight internal swarm classification database (2025).
• USGS Earthquake Catalog for New Mexico regional seismicity.
• New Mexico Bureau of Geology and Mineral Resources, Permian Basin geological framework reports.