The tsunami waves crossed the Pacific, drowning two people in Peru and causing minor damage from New Zealand to Santa Cruz, California.
New Zealand and Australia have sent military surveillance flights to Tonga to assess the damage a huge undersea volcanic eruption left in the Pacific island nation.
A towering ash cloud since Saturday's eruption had prevented earlier flights. New Zealand hopes to send essential supplies, including much-needed drinking water, on a military transport plane later Monday.
Communications with Tonga remained extremely limited. The company that owns the single underwater communications cable that connects the island nation to the rest of the world said it likely was severed in the eruption and repairs could take weeks.
The loss of the cable leaves most Tongans unable to use the internet or make phone calls abroad. Those that have managed to get messages out described their country as looking like a moonscape as they began cleaning up from the tsunami waves and volcanic ash fall.
Tsunami waves of about 80 centimetres (2.7 feet) crashed into Tonga's shoreline, and New Zealand Prime Minister Jacinda Ardern described damage to boats and coastal shops.
No casualties have been reported on Tonga, although there were still concerns about people on some of the smaller islands near the volcano. The tsunami waves crossed the Pacific, drowning two people in Peru and causing minor damage from New Zealand to Santa Cruz, California.
Scientists said they didn’t think the eruption would have a significant impact on the Earth’s climate.
Huge volcanic eruptions can sometimes cause temporary global cooling as sulfur dioxide is pumped into the stratosphere. But in the case of the Tonga eruption, initial satellite measurements indicated the amount of sulfur dioxide released would only have a tiny effect of perhaps 0.01 Celsius (0.02 Fahrenheit) global average cooling, said Alan Robock, a professor at Rutgers University.
Satellite images showed the spectacular undersea eruption Saturday evening, with a plume of ash, steam and gas rising like a giant mushroom above the South Pacific waters.
A sonic boom could be heard as far away as Alaska and sent pressure shockwaves around the planet twice, altering atmospheric pressure that may have briefly helped clear out the fog in Seattle, according to the National Weather Service.
Large waves were detected as far as the Caribbean due to pressure changes generated by the eruption.
Aid agencies said thick ash and smoke had prompted authorities to ask people to wear masks and drink bottled water.
Dave Snider, the tsunami warning coordinator for the National Tsunami Warning Center in Palmer, Alaska, said it was very unusual for a volcanic eruption to affect an entire ocean basin, and the spectacle was both “humbling and scary.”
The US Geological Survey estimated the eruption caused the equivalent of a magnitude 5.8 earthquake. Scientists said tsunamis generated by volcanoes rather than earthquakes are relatively rare.