The 2014 Iquique Earthquake: Tectonic Setting and Regional Seismic History

On 3 April 2014 at 02:43 UTC, a magnitude 7.7 earthquake struck 53 km southwest of Iquique, Chile, at a depth of 22.4 km. This event forms part of the intense seismic sequence that affected northern Chile that year and underscores the persistent activity along the plate boundary in this portion of the Andes. Northern Chile lies above the subduction zone where the Nazca Plate converges with and descends beneath the South American Plate at rates of approximately 6–7 cm per year. The geometry of the subducting slab produces megathrust earthquakes along the plate interface as well as intraslab events at greater depths. The April 2014 hypocenter at 22.4 km is consistent with rupture near the shallower portion of the seismogenic zone. The Atacama Desert region experiences minimal erosion, preserving a long-term record of coastal uplift driven by repeated large earthquakes. Seismic history in the area includes great earthquakes in 1868 and 1877 that generated destructive tsunamis along the northern Chilean coast. A notable gap in moment release persisted through much of the twentieth century, raising the potential for future large events. The 2014 sequence released strain accumulated since earlier twentieth-century shocks and was followed by extensive aftershock activity that helped delineate the rupture area. Ongoing monitoring by regional and global networks continues to refine understanding of slip behavior and stress transfer along this segment of the subduction zone. The arid climate and sparse vegetation of the region facilitate detailed paleoseismic studies of uplifted marine terraces, providing additional constraints on recurrence intervals of great earthquakes. References USGS Earthquake Catalog (event parameters as provided)