Power is being restored in Tonga's capital, and the country is sending naval boats to outlying islands to assess the damage from the huge Hunga Tonga-Hunga Ha'apai eruption and tsunami.
A New Zealand Defence Force plane has left for Tonga to assess the damage from Saturday's volcanic eruption and tsunami.
The violent eight-minute eruption of the undersea volcano Hunga Tonga-Hunga Ha'apai triggered atmospheric shockwaves and a tsunami which travelled as far afield as Alaska, Japan and South America.
The flight - which was dependant on whether the ash cloud from Hunga Tonga-Hunga Ha'apai had dissipated enough - departed from Whenuapai air base in Auckland.
Foreign Affairs Minister Nanaia Mahuta said reports overnight said there had been no further ash fall, and that there was no damage to the runway in Tonga.
"It's just a matter of clearing the ash from the runway."
Mahuta said 80 per cent of power was restored in the capital Nuku'alofa, on Tongatapu, but internet connections remained disrupted.
Damage on Tongatapu is able to be better assessed today, and the country was sending its naval capacity to the outer islands, she said.
The initial need was for water and water storage bladders, as well as food and medical supplies, she said, and Mahuta expected the Tongan government would be making a more formal request for assistance.
The RNZAF P-3K Orion will carry out a reconnaissance flight over the affected area, including low-lying islands that have not been heard from.
The Defence Force was also preparing options for naval deployments to help with the recovery.
Prime Minister Jacinda Ardern said yesterday the navy was making preparations, and either HMNZS Canterbury or HMNZS Manawanui could be deployed.
Labour MP Jenny Salesa, who is Tongan, last night joined a Zoom meeting with Tongan Methodist ministers, including Rev 'Ulufonua from Ha'apai.
He told them there had been no casualties on the group's main island. There was a lot of ash on the ground and quite a number of houses had been damaged.
"One of the main things that they're dealing with right now is the damage to the water system and the fact that not all of the people were able to protect some of the tank water that they collect from the rain," Salesa told Morning Report.
"There are 169 islands in all of Tonga, 36 of those are inhabited, and so we don't have updates from any of those other islands."
Red Cross teams in Tonga have supplies in the country to support 1200 households, their international organisation says.
International Federation of Red Cross and Red Crescent Societies Pacific head of delegation Katie Greenwood said they were able to make very brief contact with the teams in Tonga on Saturday before communication was cut.
"Red Cross teams were supporting authorities to move people to the small available amount of higher ground around capital Nuku'alofa itself and also they are well trained to be able to support any needs that are arising on the ground," she told Morning Report.
Greenwood said once communications were restored the Red Cross was looking to help connect a families' registration system where people indicate they are looking for contact with loved ones.
A P-8 aircraft from Australia's defence force is also being sent to survey critical infrastructure such as roads, ports and power lines today, if conditions permit. A statement from Australian government ministers said it was co-ordinating critical humanitarian supplies for disaster relief, and was ready to respond to further requests for assistance.
New Zealand Acting High Commissioner in Tonga Peter Lund said the capital Nuku'alofa resembled a moonscape.
Lund says Nuku'alofa was blanketed in ash, and there was a lot of damage on the waterfront and along the western coast.
There were no confirmed reports of any deaths or serious injuries, he said.
The ash cloud reached many kilometres into the air, and the eruption is thought to be the largest since Mt Pinatubo, in the Philippines, exploded in 1991.