WELLINGTON, New Zealand (AP) — A powerful underwater earthquake struck Friday off Tonga in the southern Pacific, prompting authorities to issue a tsunami advisory.

The U.S. Geological Survey said the magnitude 7.3 quake was centered 211 kilometers (132 miles) east-southeast of Neiafu, Tonga, at a depth of 24.8 kilometers (15 miles). It predicted strong shaking but said the probability of serious damage or casualties was small.

The U.S. Tsunami Warning System issued a tsunami advisory, which is one step below a tsunami warning.

An undersea volcano erupted in Tonga in January, killing three people, blanketing its main island with a thick layer of volcanic ash and shooting millions of tons of water vapor high up into the atmosphere.