Scientists with the University of Chile's National Seismological Center say the small quakes - including one stronger shake of magnitude 6 - were detected in the Bransfield Strait, a 96 km wide ocean channel between the South Shetland Islands and the Antarctic peninsula.

Several tectonic plates and microplates meet near the strait, leading to frequent rumbling but the past three months have been unusual, according to the centre.

"Most of the seismicity is concentrated at the beginning of the sequence, mainly during the month of September, with more than a thousand earthquakes a day," the centre said on Wednesday.

The shakes have become so frequent the strait itself, once increasing in width at a rate of about 7 or 8 mm a year is now expanding 15 cm a year, the centre said.

"It's a 20-fold increase ... which suggests right this minute ... the Shetland Islands are separating more quickly from the Antarctic peninsula," said Sergio Barrientos, the centre's director.

The peninsula is one of the fastest-warming places on Earth and scientists closely monitor the changing climate's impact on its icebergs and glaciers.

But climate scientist Raul Cordero of the University of Santiago said it was not yet clear how the tremors might be affecting the region's ice.

"There's no evidence that this kind of seismic activity ... has significant effects on the stability of polar ice caps," he said.

Australian Associated Press