Officials have canceled a tsunami warning issued for much of the South Pacific after a strong earthquake hit near the Tonga islands.

The U.S. National Oceanic and Atmospheric Administration says only small waves were measured in Pago Pago and the Niue Islands, the areas closest to the earthquake's epicenter.

The U.S. Geological Survey says seismologists measured the quake at a preliminary magnitude of 8, but other reports put it at 7.8. The quake hit at 1527 UTC Wednesday.

An earthquake of either magnitude has the potential to generate a destructive tsunami that can strike distant coastlines within hours.

But officials said when no major waves were observed after two hours, authorities said it is safe to assume the threat has passed.