The interior ministry said on Twitter that a tremor of magnitude 7.1 struck at 8.36 p.m. 216 km northeast of the O'Higgins Chilean scientific base and called for the coastal regions of Antarctica to be evacuated because of a tsunami risk.
The ministry also sent a message to cellphones around the country urging people to abandon coastal areas, though the ministry later said it was sent in error.
"We want to provide peace of mind to the population, tell them that it is not necessary to evacuate the entire national territory, only the Antarctic base," Miguel Ortiz of the ministry's National Emergency Office (ONEMI) told a news conference.
He said the agency regretted the inconvenience caused by its messages, which he blamed on a technical error.
The tsunami warning for Antarctica was later lifted.
People in coastal cities including La Serena, to the north of Santiago, and Valparaiso, started to leave areas close to the coast after the warning until reports started appearing that it was a false alarm.
But as Chileans were reacting to the warning, a second tremor, of magnitude 5.6, struck the Chile-Argentina border region, at 9:07 p.m., the GFZ German Research Center for Geosciences said, at a depth of 133 km and 30km east of Santiago.
No damage was reported from either quake.
The second one was close to Codelco's Andina and Teniente copper mines and Anglo American PLC's Los Bronces.
The Chilean mining regulator Sernageomin said that workers, mining operations and facilities had reported no problems after the quake.
Sernageomin said that following the first quake, 80 people were evacuated from Chile's main base in the Antarctic, the Presidente Eduardo Frei Montalva Base on Fildes Peninsula west of King George Island, and 55 more from three other bases, along with five foreign bases.The army said no damage was reported at the Antarctic base.