The 2021 M7.5 Earthquake Near Barranca, Peru

On 28 November 2021 at 10:52 local time, a magnitude 7.5 earthquake occurred 43 km north-northwest of Barranca, Peru, at a focal depth of 126 km. The event was felt across much of central Peru, including Lima, though damage remained limited due to the substantial depth and distance from major population centers.

The Peruvian coast lies above the active subduction zone formed by the Nazca Plate descending beneath the South American Plate at a rate of approximately 6–7 cm per year. This convergent margin produces both shallow thrust earthquakes and intermediate-depth events within the subducting slab. The 126 km depth of the 2021 shock places it within the Wadati-Benioff zone, consistent with intraslab seismicity rather than the plate interface itself.

Peru’s seismic history reflects continuous plate convergence. Notable twentieth-century events include the 1970 M7.9 Ancash earthquake and the 2001 M8.4 Arequipa earthquake. The 2021 event ranks among the stronger shocks recorded in the region since 2000, highlighting the persistent hazard along the central Peruvian margin.

Intermediate-depth earthquakes at 100–150 km can generate strong ground motion over wide areas because seismic waves travel efficiently through the slab. In this case, the combination of magnitude, depth, and offshore location produced moderate intensities onshore without triggering a damaging tsunami.

Ongoing monitoring by national and international networks continues to refine understanding of slab geometry and stress transfer in the subduction zone, supporting improved hazard assessment for coastal communities.

References

USGS Earthquake Catalog
Global CMT Catalog
Instituto Geofísico del Perú reports