Seismic Swarm S20240214.2 Near Whites City, New Mexico: Event Analysis and Regional Context

SeismoSight recorded swarm S20240214.2 beginning at 07:03 on 13 February 2024 and concluding at 02:53 on 15 February 2024. The sequence, located 54 km south of Whites City in southeastern New Mexico, produced 33 earthquakes over 43 hours and 49 minutes. Magnitudes ranged from 1.5 to 3.9, with the majority of events occurring at focal depths of 4–8 km. The largest shock, magnitude 3.9 at 6 km depth, took place at 20:08 on 13 February, followed within minutes by additional events of 3.2 and 3.4. Activity peaked during the evening of 13 February before tapering through 14 February and ending early on 15 February.

The swarm exhibited a typical clustered pattern: an initial foreshock phase, a mainshock sequence containing all events above magnitude 3.0, and a rapid decay in both rate and magnitude. Depths remained shallow throughout, consistent with brittle failure within the sedimentary section and uppermost basement. No single event dominated the energy release; instead, the sequence distributed moment across multiple moderate shocks, a hallmark of fluid-driven or critically stressed fault patches.

Since 1 January 2000 the same source region has hosted ten swarms. Activity remained low until 2022 (one swarm) then accelerated sharply in 2023 (nine swarms). This temporal increase aligns with broader observations of elevated seismicity rates across the northern Delaware Basin. The February 2024 swarm therefore continues a multi-year trend rather than representing an isolated episode.

Geologically, the epicentral area lies within the Delaware Basin, the western sub-basin of the Permian Basin. The basin is filled with up to 7 km of Paleozoic carbonate, evaporite, and siliciclastic strata deposited on Precambrian basement. Regional structure is dominated by north-northwest-trending normal faults that accommodated late Paleozoic extension and were later reactivated. Salt tectonics within the overlying Ochoan evaporites further complicate the shallow stress field. Although natural seismicity occurs along the larger basement faults, the recent swarm frequency and shallow depths coincide with zones of active wastewater disposal and hydraulic fracturing, where pore-pressure changes can reduce effective normal stress on pre-existing fractures.

The combination of increasing swarm counts since 2022 and the shallow, clustered nature of S20240214.2 underscores the need for continued high-resolution monitoring to distinguish tectonic from anthropogenic contributions. Future sequences will be evaluated against the same internal classification criteria used for this event.

References
USGS Earthquake Catalog (queried February 2024)
New Mexico Bureau of Geology & Mineral Resources, Delaware Basin tectonic summary
SeismoSight internal swarm database (S20240214.2 parameters)