The earthquake occurred at the boundary between the Nazca and South American plates . The two plates are converging towards each other at a rate of about 78 mm or 3 inches per year . The earthquake occurred as thrust-faulting on the interface between the two plates , with the South American plate moving up and seaward over the Nazca plate . Southwestern Peru has a history of very large earthquakes . The June 23 shock originated just southeast of the source of a magnitude 7.7 earthquake that occurred in 1996 , and it appears to have involved rupture of part of the plate boundary segment that produced an earthquake of magnitude approximately 9.0 in 1868 . The 1868 earthquake was destructive in towns that were heavily damaged in the June 23 earthquake . The 1868 earthquake produced a tsunami that killed thousands of people along the South American coast and also caused damage in Hawaii and alarm in Japan . The initial onset consists of two events separated by about 6 seconds . It is followed by at least one larger complex event occurring about 40 seconds later
1868 earthquake
1868 Arica earthquake
2001 southern Peru earthquake