Two moderate earthquakes struck near the uninhabited islands of the British overseas territory of the South Sandwich Islands on late Friday evening, seismologists said.
The first earthquake, at 10.16 p.m. local time (0016 GMT Saturday), had a magnitude of 5.6 on the Richter scale and was centered about 70 kilometers (43 miles) north of Visokoi Island, a small uninhabited island in the Traversay Island group of the South Sandwich Islands.
It struck about 64.8 kilometers (40.3 miles) deep, making it a shallow earthquake, according to the United States Geological Survey (USGS).
The Pacific Tsunami Warning Center initially measured the strength of the earthquake at 6.5 on the Richter scale, but issued no tsunami warnings.
"A destructive widespread tsunami threat does not exist based on historical earthquake and tsunami data," the center said in a bulletin.
About half an hour later, the 5.6-magnitude earthquake was followed by a 5.1-magnitude aftershock in the same area. The second earthquake had a depth of 40.7 kilometers (25.3 miles), the USGS said.
In early March, a strong 6.5-magnitude earthquake struck also near Visokoi Island, causing no damage or casualties as the region is mostly uninhabited.