Seismic Swarm Near Aykol, China: Analysis of the January 2024 Event

A seismic swarm designated S20240122.1 was recorded 131 km west-northwest of Aykol in China's Xinjiang Uyghur Autonomous Region. The sequence began at 18:27 UTC on 22 January 2024 and concluded at 12:05 UTC on 26 January 2024, spanning 89 hours and 38 minutes. During this interval, 89 earthquakes were detected, with the majority occurring at shallow depths between 1 km and 10 km.

The swarm exhibited typical characteristics of clustered seismic activity, featuring repeated events of moderate magnitude without a single dominant mainshock. Magnitudes ranged from 1.6 to a peak of 5.1, recorded at 22:21 UTC on 24 January 2024. Early phases on 22 January included several events above magnitude 4.5 within the first few hours, followed by sustained activity through 23 and 24 January. Activity gradually declined by 26 January, with final events around magnitude 4.4–4.6. Depths remained predominantly crustal, consistent with regional faulting patterns.

This area lies within the Tien Shan orogenic belt, a major intracontinental mountain range formed by ongoing convergence between the Indian and Eurasian plates. The tectonic regime produces active thrust and strike-slip faulting, resulting in elevated seismicity across northwestern China. Historical records indicate recurrent moderate earthquakes in the broader Xinjiang region, driven by north-south compression and lateral extrusion of crustal blocks.

Since 2000, only one prior swarm has been documented in the immediate vicinity, underscoring the relatively infrequent clustered sequences compared with more continuous background seismicity. The January 2024 swarm aligns with known patterns of fluid-influenced or stress-triggered activity along pre-existing faults in this compressional setting.

Such swarms provide valuable data for understanding local stress accumulation and fault interactions. Continued monitoring by regional networks supports improved hazard assessment in this tectonically active zone.

References

USGS Earthquake Catalog
China Earthquake Administration reports
Tectonic summaries from the International Seismological Centre