Tonga's volcanic eruption felt like an "atomic bomb" that shook "the whole island", an aid worker told AFP on Friday, as the Pacific nation raced to address a drinking water shortage.
Almost a week after the Hunga Tonga-Hunga Ha'apai volcano exploded, unleashing a tsunami and cutting Tonga off from the rest of the world, witnesses are recounting the disaster.
On Tongatapu, Tonga's main island, "we felt a big... it was like an atomic bomb," said Sione Taumoefolau, the secretary general for the Tonga Red Cross.
"The whole island shake because of the noise of the eruption."
The situation remains difficult, with only limited supplies of aid getting in and residents facing a massive clean up effort.
"The worst part, for us, is the ash. Everywhere we are being covered by the ashes from the volcano," Taumoefolau said.
UN crisis coordinator Jonathan Veitch told AFP from Fiji the key concern now for Tongans is drinking water, with water supplies for tens of thousands feared contaminated by ash or saltwater.
"Prior to the eruption, the majority of Tongans relied on rainwater," Veitch said. "If it's all basically made toxic by the by the ash, then they have a problem, unless they have access to groundwater sources."
Determining the location of and access to groundwater sources is now vital, he said.
Water testing has begun, but after last Saturday's eruption "the entire country is covered in ash", Veitch said.
- 'A triple whammy' -
The relief effort got under way in earnest on Thursday after Tonga's main runway was cleared of ash, allowing the arrival of military aid flights from Australia and New Zealand.
But the sheer distance, crippled communications, and the bid to keep Covid out of the kingdom of 170 islands are hampering the recovery.
Tonga has been virtually cut off from the outside world since the volcanic blast broke an undersea communications cable, which may remain severed for weeks.
"It's not an easy one. It's far from anywhere, as you know. So there are access constraints. And then the Covid issue, obviously. And then comms collapsed," Veitch said.
"So I mean, it's like, almost a triple whammy."
As foreign aid deliveries ramp up, the UN is "massively concerned" about the Covid risk posed to the island nation, Veitch said.
He pointed to current outbreaks of the virus across the Pacific, including in the Solomons and Kiribati.
"Omicron is getting out there very fast," he said.
The Tongan government is currently investigating whether there is any safe way to bring aid workers into the country.
"If there are Covid safe protocols that could be adjusted to allow safe travel into Tonga sooner rather than later we will encourage the government to do that," Veitch said.
- 'Plenty of destruction' -
The Tongan government has now completed its full assessment of the situation after the disaster, including the impact on the outer islands that were particularly hard-hit by the tsunami.
Three people have been confirmed killed, while the extent of the damage has yet to be calculated.
"They didn't have evidence that there were more casualties, but there's plenty of destruction," Veitch said.
Many people whose homes on Tonga's outer islands were destroyed have been evacuated to the larger island of Nomuka.
New Zealand's HMNZS Aotearoa berthed in Tonga on Friday, carrying a supply of fresh drinking water.
"(The ship) also the capacity to desalinate, 70-75,000 litres of water a day, which would make a difference for the population, at least on Tongatapu," Veitch said.
UNICEF has sent a large number of of water and sanitation hygiene kits on the Australian aid ship HMAS Adelaide, which departed Brisbane on Thursday night.
"We are also sending a lot of equipment into treat water," Veitch said.