Tsunami Warning Issued After Violent Volcanic Eruption Near Tonga Downgraded

Tsunami Warning Issued After Violent Volcanic Eruption Near Tonga Downgraded
Dolphins play in the heavy tsunami surf at north Salmon Creek State Beach, California. Image: Kent Porter/The Press Democrat via AP

A major volcanic eruption has rocked the small island nation of Tonga, causing tsunami warnings to go up across the Pacific from Australia to the U.S.

Spectacular and terrifying satellite imagery shows Hunga Tonga-Hunga Haʻapai volcano exploding on Saturday. A massive cloud of ash appeared over the Pacific, unleashing havoc in Tonga. The BBC reported blackouts across the island nation as well as cell phone and internet outages. The outlet also noted that people reportedly heard the sonic boom as far away as Alaska (which is more than 9,000 kilometres away), New Zealand (roughly 2,500 kilometres away), as well as in Fiji and Vanuatu.

Shortly after the eruption, a tsunami hit the capital of Nuku’alofa. The wave reached a height of roughly 1.2 metres. Despite the tense scenes, there have been no reports of casualties so far. The sun is set to rise shortly in Tonga, which will give officials a better chance to assess the damage, get the lights back on, and help residents in need.

Tsunami warnings ring the Pacific

The danger of tsunamis, however, extends well beyond Tonga’s shores. Australia and New Zealand issued tsunami warnings and told residents to avoid coastal areas, and some warnings were also issued across some parts of Canada and the U.S..

Australia also issued an evacuation order for Lord Howe Island.

The Bureau of Meteorology has since downgraded the threat level for Australia, with marine warnings now only in place for NSW, Lord Howe Island and Norfolk Island.

Hundreds of thousands of people in Japan were also advised to evacuate as waves of more than a metre hit coastal areas after the eruption, public broadcaster NHK has reported. According to the ABC, around 230,000 people were advised to evacuate across eight prefectures due to the tsunami risk.

Tsunami impacts in the U.S.

The National Weather Service Tsunami Alert tweeted that boats were washed onto docks and out of the water in parts of Hawaii in the early hours of Saturday local time. Kauai reported wave heights of just under a metre, with more, smaller pulses coming through in the following hours. Los Angeles also felt the impact, as did parts of Alaska. Alaska only saw tsunami waves less than half a metre tall in height and while these heights may not sound impressive, they still pose a major danger. The force and speed of tsunami waves can easily overtake those who get too close. In short, heed the warnings if you’re anywhere in the tsunami alert zone.

Not Tonga’s first volcanic eruption

Tonga sits along the Ring of Fire in the Pacific, home to a number of the world’s most active volcanoes. Hunga Tonga-Hunga Haʻapai is actually a relatively new volcano, at least as far as its above-water parts are concerned. It emerged from the Pacific in 2009 in the breach between two islands that are themselves part of the volcanic caldera. The volcano has expanded since 2015.

The volcano was rumbling in the month before this weekend’s major eruption. During the week spanning 2021 and 2022, the Smithsonian Volcanic Institute reported steam plumes and gases rising as high as 12,000 meters over the volcano. Those plumes were even visible on satellite imagery as the calendar turned over, apparently a precursor to Saturday’s main event.