The 2021 Southern Qinghai Earthquake: Tectonic Setting and Regional Context
On 21 May 2021 at 18:04 local time, a magnitude 7.3 earthquake struck southern Qinghai Province, China, at a focal depth of 10 km. The event occurred within the Tibetan Plateau, a region shaped by the ongoing collision between the Indian and Eurasian tectonic plates. This convergence has produced widespread crustal shortening, uplift, and active faulting across the plateau since the Eocene.
Southern Qinghai lies near the eastern Kunlun Shan, where left-lateral strike-slip faults accommodate eastward extrusion of Tibetan crust. The earthquake’s shallow depth and location reflect this tectonic regime, consistent with historical patterns of seismic release along major fault systems in the area. The plateau experiences frequent moderate-to-large earthquakes due to accumulated strain from India’s northward indentation at rates of approximately 4–5 cm per year.
Seismicity records since 2000 indicate that strong events remain relatively infrequent in southern Qinghai compared with neighboring regions, yet the 2021 event underscores the persistent hazard. Earlier notable activity includes the 2010 Yushu earthquake sequence farther east, which also occurred on strike-slip structures within the plateau. These events collectively illustrate how deformation is distributed across a network of faults rather than concentrated on a single boundary.
Geologically, the region features high-elevation basins and ranges underlain by Paleozoic to Mesozoic sedimentary and metamorphic rocks intruded by granitic bodies. Quaternary sediments in intermontane valleys overlie these older units and can amplify ground shaking. The plateau’s average elevation exceeds 4,000 m, resulting from long-term crustal thickening that continues today.
Post-event analyses confirm the 2021 rupture propagated along a previously mapped fault segment within the broader Kunlun system. No foreshock sequence of significant size preceded the mainshock, and aftershock activity decayed rapidly, typical for events in this tectonic setting.
References
USGS Earthquake Catalog (event page for 2021-05-21 southern Qinghai) China Earthquake Networks Center (CENC) official report Geological Survey of China, Tibetan Plateau Tectonic Map (updated 2020 edition)