New Zealand said Monday it was able to send a surveillance plane to assess the damage caused by the Hunga-Tonga-Hunga-Ha'apai underwater volcano.
The Hunga-Tonga-Hunga-Ha'apai underwater volcano erupted off the coast of Tonga on Saturday evening, sending a plume of ash, steam, and gas rising high into the atmosphere. The roar from the eruption was reportedly heard 10,000 kilometers (6,000 miles) away in Alaska.
After the eruption triggered a tsunami that hit the Pacific island, officials downgraded the threat of further tsunamis on Sunday.
What is the latest?
Australia and New Zealand sent reconnaissance flights on Monday to assess damage in Tonga.
Australia's Minister for the Pacific Zed Seselja said initial reports suggested no mass casualties from the eruption. However, Australian police had visited beaches and reported significant damage with "houses thrown around."
"We know there is some significant damage, and know there is significant damage to resorts," Seselja said in a radio interview. He added that Tonga's airport appeared to be in good condition.
Tonga's deputy head of mission in Australia, Curtis Tu'ihalangingie, said the flights were expected to return on Monday evening.
Tonga is concerned about the risk of COVID-19 reaching the island through aid deliveries, as it is currently COVID-free.
"We don't want to bring in another wave — a tsunami of COVID-19," Tu'ihalangingie told Reuters.
Tu'ihalangingie added that it is likely that foreign personnel would not be allowed to disembark aircraft and any aid delivered would need to be quarantined.
Tsunami threat downgraded
The tsunami threat around the Pacific basin from a powerful underwater volcano eruption off the coast of Tonga began to recede on Sunday, the Pacific Tsunami Warning Center said.
Authorities at "impacted coastal areas should monitor... to determine when it is safe to resume normal activities," the center said.
The seismic force sent powerful waves crashing into coastlines from Japan to the United States.
The US National Weather Service in American Samoa cancelled its tsunami advisory on Monday, but officials urged caution when entering the water.
In Peru, two women died in Lambayeque due to "anomalous waves."
'Significant' damage to Tonga capital
Officials and emergency crews hope that the flights on Monday will provide a clearer picture of the damage on Tonga.
A full assessment was not possible as of Sunday, as the eruption knocked out the internet and disrupted communication with the island. Tonga receives its internet via an undersea cable from Fiji.
However, New Zealand Prime Minister Jacinda Ardern said at a press briefing Sunday that Tonga's capital, Nuku'alofa, suffered "significant" damage.
"The tsunami has had a significant impact on the foreshore on the northern side of Nuku'alofa with boats and large boulders washed ashore," she said after managing to contact the New Zealand embassy in Tonga.
"Nuku'alofa is covered in a thick film of volcanic dust but otherwise conditions are calm and stable," the prime minister added.
There were no official reports of injuries or deaths in Tonga, she said, while cautioning that authorities were yet to contact some coastal areas and smaller islands.
"Communication with Tonga remains very limited. And I know that is causing a huge amount of anxiety for the Tongan community here," the prime minister said.
The thick ash cloud 63,000 feet (19,000 meters) above Tonga had previously prevented military surveillance flights.
'One of the most explosive eruptions in the 21st century'
Experts expressed concern about the sheer size of the eruption and are on the lookout for potentially further volcanic activity.
"It was a remarkable eruption. It was extremely explosive. We're sort of thinking it's one of the most explosive eruptions in the 21st century at the moment," Shane Cronin, professor of volcanology at the University of Auckland in New Zealand, told DW.
"These very large ones at this volcano happen about once every 900 years, but they seem to have a series of events, and so this may be the first in a series of eruptions," he added.
In terms of damage, the expert said the main concerns at the moment are about how hard the tsunami hit, as well as the level of ash that has fallen on the island.
"So far, what we've seen has been tsunami damage, and most of what we've seen has been from Tongatapu — the main inhabited island of Tonga where the capital Nuku'alofa is," Cronin said.
"What we're concerned about is some of the low-lying islands, which are actually very close to Hunga-Ha'apai - Nomuka and the islands of the Ha'apai group. These islands have potentially a lot of low-lying areas that were affected by tsunami waves," he added.
"At the moment, the ashfall that has gone on to Tongatapu hasn't been that large yet, but the eruption column actually spread in a way that it probably would have [and possibly still will] put more ash onto the central part of the Tongan island group," the volcanologist said.
"What we're waiting to find out now is that what kinds of impacts there have been, what kind of help people need."
International support
Besides New Zealand, other countries have expressed concern for Tonga and offered help.
An Australian government spokesperson said initial assessments were still underway, but the country was ready to provide support to Tonga if requested.
US Secretary of State Antony Blinken also expressed concern, adding that the US "stands prepared to provide support to our Pacific neighbors."
However, international aid efforts were complicated by the fact that Tonga, home to about 105,000 people, is one of the rare countries that have avoided any COVID-19 outbreaks.
New Zealand has assured that its military staff was all fully vaccinated and willing to follow any protocols established by the island nation.