A 6.4-magnitude earthquake jolted western Argentina and parts of Chile, with no immediate reports of damage, authorities said.
The quake rocked San Juan province at 1757 local time, striking at a depth of about 130 kilometers (80 miles), Argentina's seismological institute said.
In Chile, the quake was measured at a magnitude of 6.5, officials at the government's National Emergency Office (ONEMI) said.
The earthquake was felt in northern and western Chile in the regions of Atacama, Coquimbo, Valparaiso, 0'Higgins and the Santiago metro area.
Cellular phone service was briefly knocked out in San Juan province.