At 15:43GMT Wednesday, a powerful earthquake measuring 7.7 on the Richter scale rocked northern Chile. There have so far been no immediate reports of injuries.

The earthquake occurred about 60km deep, and was centered about 106km west of the town of Calama. According to Carmen Fernandez, director of Chile's national emergency office, the quake stretched across nearly 2,000km, all the way from Chile's northern border with Peru to the capital, Santiago.

"It is a major quake," said Fernandez.

Cement cracked at an airport in Antofagasta, where staff had to be evacuated. The cities of Calama and Arica in the north lost electrical power, and panicked residents flood the streets.

As a result of the massive earthquake, U.S. officials have also issued a tsunami alert in the Pacific. The alert was issued by the Pacific Tsunami Warning Centre in Hawaii, and covers areas "bordering the Pacific Ocean and adjacent seas" off the coasts of Chile and Peru.

In a separate incident, another South American country was shaken by an earthquake today. The western Argentine city of San Juan experienced a 4.5 quake, also with no injuries thus far reported.

South America was plagued earlier this year with an even bigger earthquake measuring 8.0 on the scale, which killed 540 people, and left another 200,000 homeless.