A 6.0-magnitude earthquake struck off the Pacific nation of Tonga late Sunday, US seismologists said, but no tsunami warning was issued.
The US Geological Survey said the quake was shallow, striking 140 kilometres (87 miles) northeast from the town of Hihifo.
A second 5.5 quake struck shortly afterwards in the sea 110 kilometres away from Hihifo, USGS reported.
The Pacific Tsunami Warning Center did not immediately issue any warnings.
Tonga sits on the so-called Pacific Ring of Fire, a region of frequent seismic activity due to collisions between continental plates.