Seismic Swarm Analysis: Delaware Basin, New Mexico – December 2023

A seismic swarm designated S20231205.1 occurred 55 km south of Whites City, New Mexico, in the Delaware Basin. The sequence began at 07:01 on 4 December 2023 and concluded at 07:05 on 6 December 2023, registering 39 earthquakes within a 48-hour period. Event depths ranged primarily between 4 km and 8 km, with magnitudes spanning from –0.5 to 4.0. The largest event reached magnitude 4.0 at 23:59 on 4 December, followed closely by multiple events of magnitude 3.0–3.3 on the same day and the following morning.

The Delaware Basin forms the western subdivision of the Permian Basin and consists of thick Paleozoic carbonate and evaporite sequences overlying Precambrian basement. Regional tectonics are influenced by the buried Central Basin Platform and the western margin of the Central Basin Uplift, where reactivated basement faults accommodate both natural and anthropogenic strain. Seismicity in this area has increased since the mid-2000s, coinciding with expanded horizontal drilling and large-volume wastewater injection into deep Ordovician and Silurian formations.

Historical records since 2000 indicate six documented swarms in the immediate vicinity, with one swarm recorded in 2022 and five in 2023. These clusters typically exhibit shallow-to-mid-crustal depths (2–8 km) and short durations of one to three days, consistent with fluid-pressure diffusion along pre-existing fracture networks.

Within swarm S20231205.1, the initial 24 hours featured the highest rate of activity, including the sequence’s peak magnitude of 4.0 and several events above magnitude 3.0. Subsequent activity on 5 December showed a gradual decline in both rate and maximum magnitude, with events predominantly at 6 km depth. By 6 December, only two final events were recorded before the swarm terminated. Focal depths clustered tightly around 6 km for the majority of events above magnitude 2.0, suggesting a common source volume within the lower sedimentary section or uppermost basement.

Such swarm characteristics align with patterns observed elsewhere in the Permian Basin, where pore-pressure perturbations from injection can trigger episodic failure on critically stressed faults. The December 2023 sequence did not produce reported damage or felt intensities beyond local areas, consistent with its moderate magnitudes and rural epicentral location.

References

USGS Earthquake Catalog (earthquake.usgs.gov)
New Mexico Bureau of Geology and Mineral Resources – Delaware Basin seismicity reports
SeismoSight internal swarm classification database