Both earthquakes occurred as the result of normal faulting at a depth of approximately 600 km, almost 1000 kilometers east of the Peru-Chile Trench within the subducted oceanic lithosphere of the Nazca plate. Focal mechanisms indicate rupture occurred on either a north or south-southeast striking, moderately dipping normal fault. At the location of the earthquakes, the Nazca plate subducts to the east under the South America plate at a velocity of about 69 mm/yr.
