Major 7.4 Magnitude Earthquake Strikes Near San Pedro de Atacama, Chile

On July 19th, 2024, the region near San Pedro de Atacama in Chile was shaken by a powerful 7.4 magnitude earthquake, significantly impacting the Andean community. The tremor, resulting from normal faulting within the Nazca plate, originated at an intermediate depth of approximately 120 kilometers. It marks another major seismic movement in an area already known for its geological activity.

Occurring near the juncture of Chile, Argentina, and Bolivia, the quake's depth classifies it as an intermediate-depth earthquake, typically ranging from 70 to 300 kilometers below the surface. Unlike shallow-focus earthquakes that have been central to the region's seismic history, such as the 2010 Maule tremor and the 1960 Valdivia quake, the July 19th event stems from deformation deep within the subducting Nazca slab, rather than at the plate interface.

The ongoing subduction of the Nazca plate under the South American plate, at a rate of roughly 74 millimeters per year, not only results in coastal upheavals but also triggers activity far beneath the surface as the plate is forced to bend. Such bending leads to extension and can cause normal faulting earthquakes where the slab becomes overstretched and cracks.

While intermediate-depth earthquakes are generally less destructive than their shallow counterparts, they can be felt over vast areas. The location of this quake implies the presence of a flatter dip in the slab, indicating that such tremors can be expected to strike further inland than usual for the region.

The tectonic narrative of South America and the Nazca plate includes a history of significant seismic episodes. The past century alone has seen seven other events with magnitudes of 7.0 or higher within 250 km of the most recent quake, with one of the most notable being the 8.2 magnitude shake in 1950. And though damage from intermediate-depth quakes has often been less, there have been exceptions, such as the 2005 event in northern Chile, which caused more than 200 injuries.

The 2024 earthquake serves as a stark reminder of the dynamic and volatile nature of Earth's lithosphere, especially in regions where tectonic plates interact with such force and complexity. Continuing research and monitoring are essential in understanding these natural phenomena and improving preparedness for future seismic activity in the region.