The 2005 Tarapacá Earthquake and Seismic Context of Northern Chile

On 13 June 2005 at 22:44 UTC, a magnitude 7.8 earthquake struck the Tarapacá region of northern Chile. The event occurred at a depth of 100 km. Its epicenter was located in Tarapacá, with a closely related report placing it 102 km east-northeast of Iquique, approximately 20 km from the primary epicenter. This intermediate-depth quake was felt across northern Chile and southern Peru, causing localized damage but limited casualties due to its depth and the region’s building practices. Northern Chile lies within the Andean subduction zone, where the Nazca Plate converges with and subducts beneath the South American Plate at a rate of approximately 6–7 cm per year. This tectonic setting produces frequent seismicity, including both shallow crustal events and deeper intraslab earthquakes. The Tarapacá region, part of the Atacama Desert, sits above the subducting slab, which descends steeply in this segment of the margin. Intermediate-depth earthquakes like the 2005 event typically result from internal deformation within the downgoing Nazca slab rather than slip on the plate interface. Seismic history in the area reflects the ongoing subduction process. Large earthquakes have repeatedly affected northern Chile, with notable events including the 1877 Iquique earthquake and earlier historic shocks documented in colonial records. Since 2000, the region has experienced additional strong shaking, though the 2005 Tarapacá earthquake remains one of the largest in the immediate vicinity during that period. The 2005 event highlighted the persistent hazard from intraslab seismicity at depths around 100 km. Post-event studies confirmed that the rupture occurred within the subducting plate, consistent with the observed depth and focal mechanism. Ground shaking reached intensity VII in parts of Iquique and nearby communities, prompting reviews of seismic building codes in the region. No major tsunami was generated, as expected for an intermediate-depth event. Ongoing monitoring by national and international networks continues to track activity along the northern Chile margin. The 2005 Tarapacá earthquake serves as a reminder of the persistent seismic risk in this tectonically active zone.

References

USGS Earthquake Catalog (event parameters as provided)