WELLINGTON, New Zealand — New Zealand and Australia have sent military surveillance flights to assess the damage in Tonga caused by Saturday's huge undersea volcanic eruption.

Communications with the Pacific island nation have remained limited since the eruption. The blast likely severed the single underwater cable that provides internet and international phone service.

No casualties have been confirmed on Tonga, although a British woman is reported missing. Officials in nearby countries have warned that casualty numbers could skyrocket once communication is re-established.

"Communication with Tonga remains very limited. And I know that is causing a huge amount of anxiety for the Tongan community here," New Zealand Prime Minister Jacinda Ardern said.

Residents who got messages out to the world described a moonscape left by tsunami waves and volcanic ash fall.

The ash was contaminating drinking water, and New Zealand is planning to fly water and other supplies to Tonga on Tuesday.

According to CNN, the blast on Saturday was likely the most violent eruption the world has seen in three decades. Following the explosion, tsunami advisories briefly went out across the Pacific Rim from Japan to Southern California to South America.

"The eruption was very powerful. There are reports it was heard as far as Alaska," Wendy K. Stovall, a member of the USGS Volcano Hazards Program, told KPIX-TV in San Francisco.

WELLINGTON, New Zealand — The tsunami threat around the Pacific from a huge undersea volcanic eruption has begun to recede, while the extent of damage to Tonga remains unclear.

The eruption on Saturday sent tsunami waves swirling around buildings and people rushing to higher ground. There were no immediate reports of injuries or damage because all internet connectivity with Tonga was lost.

Following the eruption, a tsunami advisory was issued for Japan, Hawaii, Alaska and the U.S. Pacific coast.

Authorities in Southern California closed beaches and piers as a precaution.

The Hunga Tonga Hunga Ha’apai volcano is located about 40 miles north of Tonga's capital.

Video posted to social media shows large waves washing ashore in coastal areas, swirling around homes and buildings. Satellite images show a 3-mile-wide plume of ash, steam and gas rising up into the air 12 miles high.

Tonga's King Tupou VI was reportedly evacuated from his palace near the shore, among the many residents who headed for safety.

About 105,000 people live in Tonga.

A series of eruptions in 2014 and 2015 disrupted international air travel to the Pacific archipelago for several days.