A four-foot tsunami wave reportedly hit Tonga’s capital, Nuku’alofa, on Saturday, sending people rushing for higher ground. Witnesses said ash fell from the sky, after an undersea volcano erupted earlier near the remote Pacific nation.
The volcano, Hunga Tonga-Hunga Ha’apai, is about 40 miles north of the Pacific archipelago’s main island, Tongatapu.
Australia’s Bureau of Meteorology reported the tsunami on Twitter. But communication with Tonga was cut off, according to the Associated Press, so there were no immediate official reports of the injured or the extent of the damage.
The Tonga Meteorological Service issued a tsunami warning for the archipelago on Saturday evening. On their Facebook pages, the Meteorological Services of Fiji and neighboring Samoa also issued tsunami warnings, advising people to stay away from low-lying coastal areas.
The U.S. National Tsunami Warning Center issued a tsunami advisory for the west coast Saturday morning Pacific time, including the Washington and Oregon coast, with the National Weather Service in Portland already reporting waves of one to three feet on Twitter in Newport, Oregon, Long Beach, Washington and Seaside, Oregon. “The first wave may not be the highest so later waves will be bigger,” the tweet read.
The volcano had been relatively inactive for several years, but began erupting intermittently in December. By Jan. 3, activity had decreased significantly, according to a report from the Smithsonian Institution’s Global Volcanism Program.
In 2014, the volcano erupted, spawning a new island that eventually became home to thriving vegetation and barn owls, according to the BBC.
Satellite imagery of Saturday’s eruption, shared on Twitter by New Zealand’s National Institute for Water and Atmospheric Research, showed a “brief spike in atmospheric pressure as the atmospheric shock wave was pulsing through New Zealand”.
Other recent infrared satellite images suggested the submarine volcano was still erupting, and despite Tonga’s geographic isolation, a resounding sound was heard after the initial eruption as far as New Zealand (which lies 1,100 miles northeast of Tongatapu) according to Weather Watch, a private meteorologist in the countryside.
Saturday’s eruption sent a plume of gas and ash about 20 kilometers into the atmosphere, according to initial reports.
New Zealand’s National Emergency Management Agency issued a tsunami warning in a statement on Saturday, advising coastal residents to expect “unusual strong currents and unpredictable shoreline surges”.
In a Twitter thread, Smithsonian Institution volcanologist Dr. Janine Krippner said “the majority of the volcano is submarine.”
The strength and potential impact of an eruption is estimated using a Volcanic Explosiveness Index, or VEI, which takes into account the volume of material ejected during the eruption and the height of the plume reached. The VEI for Saturday’s eruption has yet to be estimated, but prior to the eruption the volcano was estimated capable of producing an eruption with a maximum VEI of 2.
Flares with a VEI of 6 or more send so much gas and particles so high into the atmosphere that they can have a cooling effect on the climate for several years, by reflecting more sunlight away from the Earth’s surface. . But eruptions of this magnitude occur very rarely. The latest was Mount Pinatubo in the Philippines in 1991.
Henry Fountain contributed report.