Seismologists say two powerful earthquakes struck near the South Pacific island nations of Papua New Guinea and Tonga on Sunday.
No casualties have been reported.
The U.S. Geological Survey said a magnitude 6.2 quake struck near Papua New Guinea's New Britain region. Some 20 minutes later, a 5.9 magnitude quake struck near the island of Tonga.
The quakes follow Saturday's 6.3 magnitude tremor in central Indonesia, but experts say they are probably not related.
All three occurred along the seismically-active Asia-Pacific rim, where movement by the massive Pacific tectonic plate creates regular earthquakes and volcanic activity.
Seismologists are closely monitoring activity at Indonesia's volatile Mount Merapi volcano which is also located along the Pacific rim.
Scientists say it is difficult to determine if any of the recent volcanic eruptions and earthquakes are related, because tectonic forces are complex. Scientists say it is likely the activity is merely coincidental.