Two Navy ships will leave New Zealand today to meet an unknown challenge in Tonga after a massive volcanic eruption.
Local community leaders are already mobilising to help, with a pre-season Moana Pasifika rugby match expected to raise funds for disaster relief.
Hunga Tonga-Hunga Ha'apai island was largely destroyed after Saturday's underwater volcanic eruption.
The extent of damage across the country is still not fully understood, Government ministers said this afternoon.
Foreign Affairs Minister Nanaia Mahuta said an Air Force P-3K2 Orion had captured images of the devastated area, and shared these details with Tongan authorities.
"However, images show ashfall on the Nuku'alofa airport runway that must be cleared before a C-130 Hercules flight with humanitarian assistance can land," Mahuta added.
"Communication issues caused by the eruption have made this disaster response particularly challenging," she said.
"The delays mean we have taken the decision for both HMNZS Wellington and HMNZS Aotearoa to sail, so they can respond quickly if called upon by the Tongan Government."
Defence Minister Peeni Henare said water was among the highest priorities for Tonga now.
HMNZS Aotearoa can carry 250,000 litres, and produce 70,000 litres per day through a desalination plant, he said.
A C-130 Hercules aircraft is on standby to deliver humanitarian aid and disaster relief stores, including collapsible water containers, generators and hygiene kits.
But the airport runway will have to be cleared first.
Savae Sir Michael Jones said leaders from the Tongan community were mobilising fast and working with friends to prepare relief.
"We're part of this big family. We all feel the pain of another family member," Jones said today.
Tongan Advisory Council chair Melino Maka approached Jones, in part because of the rugby star's links to shipping businesses.
Jones said shippers might be able to supply the Navy with containers or otherwise help get provisions to Tonga.
"We're all poised to help in any way we can."
Jones said there were many unknowns and everybody was waiting for a situation report.
"We're getting indications of a loss of life, which is tragic."
He told the Herald volcanic ashfall contaminating drinking water sources was also a major concern.
But he was confident relief efforts could use templates from lessons learned in previous catastrophes.
"This isn't the first time, sadly, that the Pacific has been hit."
Cyclone Gita devastated Tonga in early 2018 and nine years before that, a major earthquake and tsunami struck Samoa.
Jones said New Zealanders rallied to help Pacific neighbours after those tragedies.
"I don't expect it to be any different with the latest natural disaster."
As chair of the Moana Pasifika super rugby franchise, Jones said an early February pre-season game against the Chiefs would raise funds and honour the Tongan community.
"I have to allow the Tongan community to drive all this and take the lead," he added. "We're just here to support in any way we can."
And as the days go by with little or no contact, Maka says help is needed now.
"Looking at the scale, some of the images, we're just crossing our fingers and praying that the casualties are not going to be really devastating," he said today.
"The dust is quite thick in some areas and also I saw video of a family ... they were climbing on the roof of the house to save themselves."
Maka said satellite phones were the only way to contact people in Tonga but not many people in the country had those phones.
"It's frustrating because you'd think the Government of Tonga would be sending out some official statement."
Maka said he hoped local donors could supply water, non-perishable food and useful tools and implements as soon as possible.
"These things will assist our community to rebuild their lives."
He said footage appeared to show major disruption on the island of 'Eua, southeast of the kingdom's main island of Tongatapu.
"I saw some footage that the waves picked up some of the four-wheel-drives."
It was unknown how widely the archipelago was affected but Maka said based on the size of the eruption, the whole country was probably impacted.
He said there were no reported deaths in the Ha'apai island group, but the extent of damage was still not known.
"It's just like walking in the dark."