Images reveal devastation in tsunami-hit Tonga

A volcano that exploded on the Pacific island nation of Tonga has almost disappeared from view, new images revealed Tuesday, with swathes of the island nation smothered in grey ash and dust or damaged by a tsunami.

Tonga has been virtually cut off from the rest of the world since Saturday's volcanic blast -- one of the largest recorded in decades.

The volcano erupted 30 kilometres (about 19 miles) into the air and deposited ash, gas and acid rain across a large area of the Pacific.

Three days after the eruption, the outside world is still scrambling to understand the scale of the disaster, using patchy satellite phone connections, surveillance flights and satellite images.

New Zealand said two people have been confirmed killed, citing Tonga police on the island. One of them is a British woman. Her family say the body was found after she was swept away by the tsunami.

Satellite images released by Maxar Technologies on Tuesday showed that where most of the volcanic structure stood above sea level a few days ago, there is now just open sea.

Only two relatively small volcanic islands were still visible above sea level after the eruption.

In fact, “what we saw above the water--that has now been destroyed--was only the tip of a volcano that had grown on the rim of the massive underwater volcano,” said Monash University vulcanologist Heather Handley.

New Zealand released aerial images taken from a surveillance flight the previous day, revealing a tree-lined coast transformed from green to grey by the volcanic fallout.

Wrecked buildings were visible on the foreshore alongside others that appeared intact.

Volcanic ash blanketed island fields, images from an Australian Defence Force P-8A Poseidon patrol aircraft showed.

Shipping containers had been knocked over like dominoes at a port on the main island.

Australia's HMAS Adelaide and New Zealand's HMNZS Wellington and HMNZS Aotearoa were ordered to be ready for a possible aid request from Tonga, which lies three-five days' sailing away.

With water sources feared to be poisoned by volcanic fallout, the Red Cross said it was sending 2,516 water containers.

France, which has territories in the South Pacific, pledged to help the people of Tonga's "most urgent needs".

The UN said a signal had been detected from a distress beacon on a low-lying island, Mango.

The UN Office for the Coordination of Humanitarian Affairs said surveillance flights had confirmed “substantial property damage” on Mango, home to some 30 people, and another island, Fonoi.

The UN agency also reported "extensive damage" on the western beaches of the main island Tongatapu, "with several resorts and/or houses destroyed and/or badly damaged".

Tonga's capital Nuku'alofa was shrouded in two centimetres of volcanic ash and dust, it said.

Power had been restored to parts of the capital. Local phone systems had been restored but international communications were severed.