New Zealand is standing by to send help to its Pacific neighbour Tonga as soon as conditions allow.
The eruption’s shockwave sent out a sonic boom which was heard in New Zealand and further afield.
Communication with Tonga at the moment is very limited due to power cuts and an undersea communications cable being “impacted”.
New Zealand, Japan and the US have too felt the effects of the volcano.
Tsunami advisories were also issued by the US Tsunami Warning System for the US Pacific coast, Alaska and Hawaii.
Beaches around the country were also closed.
In Japan, boats were toppled by tsunami waves, while waves were observed in California and Alaska.
A Royal New Zealand Air Force aircraft is set to take a reconnaissance flight on Monday to assess the area near Tonga and low-lying islands.
The flight would assist in an initial impact assessment of the volcano and tsunami.
The P-3K Orion is due to depart at 8am from Auckland’s Whenuapai base early on Monday morning, dependent on the ash cloud dissipating enough to enable safe flying in the area.
A navy vessel is also on standby to help if needed.
Prime Minister Jacinda Ardern said on Sunday: "We want to be in Tonga and on the ground as soon as we are possibly able to".
She said as yet "there are no official reports of injuries or deaths in Tonga".
An initial $500,000 has been set aside to help.
The Hunga-Tonga-Hunga-Ha'apai volcano had been active from December 20, 2021 but was declared dormant on January 11.
It began erupting again on January 14, with the large, major eruption happening on Saturday.
That eruption may be the biggest blast since Mount Pinatubo in the Philippines 30 years ago one volcanologist says.