2025 Southern Tibetan Plateau Earthquake Swarm

The 2025 Southern Tibetan Plateau Earthquake Swarm, designated PS20250107.1 by SeismoSight, began at 01:05 UTC on 7 January 2025 and concluded at 01:37 UTC the same day. Within this 31-minute window, seven earthquakes were recorded, centered in the southern Tibetan Plateau. The sequence initiated with a magnitude 7.1 mainshock at a depth of 10 km, followed by six aftershocks ranging from magnitude 5.0 to 5.4, all occurring at identical 10 km depths.

This rapid succession of events highlights typical swarm characteristics in tectonically active regions, where clustered seismicity occurs without a single dominant aftershock decay pattern. The mainshock registered 8 km from the swarm centroid, underscoring localized stress release along active fault structures.

The southern Tibetan Plateau forms part of the Himalayan-Tibetan orogen, resulting from the ongoing collision between the Indian and Eurasian plates that began approximately 50 million years ago. This convergence has elevated the plateau to an average height exceeding 4,500 meters, with crustal thickening and eastward extrusion accommodating much of the strain. The region experiences frequent moderate to large earthquakes due to thrust faulting along the Main Himalayan Thrust and associated strike-slip systems such as the Karakoram Fault. Seismicity is concentrated at shallow depths, often between 5 and 20 km, consistent with the 10 km focal depths observed in this swarm.

Historical records indicate limited swarm activity since 2000. Only two swarms have been documented in the area, with the first occurring in 2015. The 2025 event marks the strongest since that period, featuring the sole magnitude 7.1 earthquake recorded in the region during this timeframe.

Geological monitoring shows that such swarms often precede or accompany larger strain releases in the plateau's southern margin, where India-Eurasia convergence rates average 4–5 cm per year. The uniform 10 km depths across all events suggest rupture within a consistent brittle crustal layer influenced by regional décollement surfaces.

SeismoSight classification identifies this sequence as an internal swarm event, providing data for refined seismic hazard models in the plateau. Continued observation of similar clusters aids in understanding stress migration along major fault zones.

References

SeismoSight internal swarm database PS20250107.1
USGS Earthquake Catalog (regional tectonics summaries)
Geological Survey of India (Himalayan orogen reports)