The 2007 Tocopilla Earthquake and Seismic Geology of Northern Chile

On November 14, 2007, at 15:40 local time, a magnitude 7.7 earthquake struck 36 km east-southeast of Tocopilla, Chile, at a depth of 40 km. This event represents a significant instance of seismic activity in northern Chile since 2000, occurring directly within the listed strong earthquake record for the region. Northern Chile lies along the active subduction zone where the Nazca Plate converges with and descends beneath the South American Plate. This tectonic interaction drives the region's high seismicity, with the downgoing slab generating both interplate thrust earthquakes and intraslab events at varying depths. The 40 km focal depth of the 2007 Tocopilla earthquake places it within the coupled portion of the subduction interface, consistent with the geometry of the Wadati-Benioff zone in this segment of the Andean margin. The geological history of the area reflects prolonged plate convergence that has shaped the Andean orogen over millions of years. Uplift of the Coastal Cordillera and development of the Atacama Desert are direct consequences of this subduction-driven compression and associated volcanic arc activity farther east. Fault systems in the forearc, including those near Tocopilla, accommodate some of the strain through crustal deformation, though the dominant release occurs along the megathrust. Seismic patterns in northern Chile demonstrate recurring large-magnitude events tied to the subduction cycle. The 2007 earthquake released accumulated strain along a portion of the plate boundary previously identified as a seismic gap following earlier 19th- and 20th-century ruptures. Post-event aftershock distributions aligned with the subduction interface, illustrating the continued adjustment of stresses in the downgoing slab. The combination of plate-boundary tectonics, crustal faulting, and historical recurrence underscores the persistent seismic hazard in the Tocopilla region. Ongoing monitoring of subduction zone dynamics continues to inform understanding of how such events fit within the broader framework of Andean margin evolution.

References

USGS Earthquake Catalog Global CMT Project Chilean National Seismological Center (CSN) reports