Seismic Swarm S20221116.2: Analysis of Activity Near Mentone, Texas

Seismic swarm S20221116.2 was recorded in western Texas, centered 37 km west-southwest of Mentone. The sequence began at 18:42 on 16 November 2022 and concluded at 03:18 on 30 November 2022, spanning 320 hours and 35 minutes. During this period, 265 earthquakes were detected.

The first 100 events reveal a rapid onset followed by sustained low-to-moderate activity. The initial event measured magnitude 2.1 at 7 km depth. Within three hours, a magnitude 5.4 earthquake occurred at 6 km depth, marking the largest event of the swarm. Subsequent events clustered tightly in time, with 22 additional shocks recorded before midnight on 16 November. Magnitudes ranged predominantly between 1.5 and 2.8, while depths remained shallow, concentrated between 4 km and 10 km.

Analysis of the initial sequence shows a high rate of aftershocks immediately following the magnitude 5.4 mainshock. Events on 17 November maintained similar depth ranges, with occasional spikes such as a magnitude 3.6 at 7 km and a magnitude 3.8 at 7 km. By 18 November, activity had begun to decline in both frequency and peak magnitude. The majority of events fell below magnitude 2.5, consistent with typical swarm behavior where energy release occurs through numerous smaller ruptures rather than a single dominant shock.

The region lies within the Delaware Basin, part of the larger Permian Basin in West Texas. This geological province features thick sequences of Paleozoic sedimentary rocks overlying Precambrian basement. The basin has experienced natural tectonic stress from regional fault systems, including the Central Basin Platform and the western margin of the Central Basin Platform. Historical records indicate low background seismicity prior to extensive hydrocarbon development, with modern activity largely attributed to fluid injection associated with oil and gas operations.

Updated geological assessments confirm that the shallow focal depths observed in swarm S20221116.2 align with depths commonly linked to wastewater disposal wells in the Permian Basin. The temporal clustering and spatial concentration further support the interpretation of induced seismicity within this tectonically stable but anthropogenically influenced setting.

Overall, swarm S20221116.2 exemplifies the characteristic pattern of injection-related sequences in the region: an abrupt energetic onset, rapid decay in event size, and persistence of microseismicity over days to weeks.

References

• USGS Earthquake Catalog (earthquake.usgs.gov)
• Texas Bureau of Economic Geology, Permian Basin Studies
• SeismoSight internal swarm classification S20221116.2