Seismic Swarm S20250812.1: Analysis of Activity Near Whites City, New Mexico

A seismic swarm designated S20250812.1 was recorded 56 km south of Whites City, New Mexico, beginning at 16:30 on 11 August 2025 and concluding at 08:51 on 16 August 2025. Over 112 hours and 20 minutes, the sequence included 68 earthquakes. Events ranged in magnitude from 0.6 to 3.5, with the largest occurring on 12 August at 06:58:52. Focal depths remained shallow, primarily between 4 km and 8 km, consistent with activity in the upper crust of the Delaware Basin.

The swarm exhibited typical characteristics of clustered seismicity, featuring an initial rise in event rate followed by a gradual decline. Early activity on 11 August included multiple events above magnitude 2.0, such as a magnitude 2.3 at 18:32 and a magnitude 2.2 at 23:56. Peak intensity occurred on 12 August, highlighted by the magnitude 3.5 mainshock and additional events of magnitude 2.6 and 2.2. Subsequent days showed sustained but diminishing activity, with magnitudes generally below 2.0 after 14 August. Depths showed minor variation but stayed within a narrow band indicative of a localized source zone.

This region lies within the Delaware Basin, a major subdivision of the Permian Basin in southeastern New Mexico and western Texas. The basin formed during the late Paleozoic era through subsidence and sediment accumulation, resulting in thick sequences of carbonates, evaporites, and clastics. Tectonic setting involves the western margin of the Central Basin Platform and proximity to the Rio Grande Rift influence, where extensional faults create pathways for fluid migration. Natural seismicity is low to moderate, but human-induced activity has increased due to extensive oil and gas operations involving wastewater injection.

Historical records since 2000 indicate 24 prior swarms in the immediate area. Activity accelerated notably from 2022 onward, with one swarm in 2022, nine in 2023, five in 2024, and nine in 2025 up to the current event. These episodes commonly feature similar magnitude ranges and shallow depths, often linked to fluid pressure changes along pre-existing faults.

The S20250812.1 swarm aligns with patterns observed in the Permian Basin, where induced seismicity arises from industrial fluid disposal. Depths of 4–8 km correspond to intervals where injection targets frequently occur. No damage or felt reports beyond the immediate vicinity were associated with this sequence, reflecting the modest maximum magnitude.

References
SeismoSight internal swarm classification S20250812.1
USGS Earthquake Catalog (regional Delaware Basin data)
New Mexico Bureau of Geology and Mineral Resources (Permian Basin tectonics)