Deep-Focus Earthquake Near Iñapari, Peru

On November 24, 2015, at 22:45 UTC, a magnitude 7.6 earthquake struck 155 km west-northwest of Iñapari in southeastern Peru. The event occurred at a focal depth of 606.2 km, classifying it as a deep-focus earthquake. Such events typically produce limited surface damage despite their size due to energy dissipation over great distances. The epicentral region lies within the Amazonian foreland of Peru, near the borders with Brazil and Bolivia. This area forms part of the South American tectonic plate, where the Nazca plate subducts eastward beneath the continent along the Peru-Chile trench. Deep seismicity results from the descent of the cold oceanic slab into the mantle transition zone, reaching depths exceeding 600 km. The 2015 event aligns with this pattern of intermediate- to deep-focus activity characteristic of the Andean margin. Historical records document recurrent strong earthquakes in the broader Peruvian subduction zone. Notable events since 2000 include a magnitude 7.6 earthquake on the same date located 185 km west-northwest of Iñapari and a magnitude 7.1 event on August 24, 2018, situated 136 km west of the town. These occurrences cluster within tens of kilometers of the 2015 mainshock, underscoring persistent seismic release along the subducting slab. Geological studies of the region highlight the role of the subducted Nazca plate in generating both shallow crustal deformation in the Andes and deep intraslab earthquakes. The remote location of Iñapari, situated in the Madre de Dios department amid lowland rainforest, reduces exposure to strong ground shaking. No significant aftershocks or secondary hazards such as landslides were widely reported following the 2015 event. Ongoing monitoring by regional seismic networks continues to track slab dynamics in this sector of the Andes. Updated catalogs confirm the listed events as among the strongest recorded near Iñapari since the start of the twenty-first century, providing data for refining models of mantle structure and subduction processes.

References

USGS Earthquake Catalog Global CMT Project Peru Instituto Geofísico del Perú seismic reports