Image: Jacaranda FM
Scientists reported Sunday that a gigantic underwater volcanic eruption in Tonga was so powerful that it was recorded worldwide and caused a tsunami that flooded Pacific coasts from Japan to the United States.
Satellite photographs revealed the Hunga Tonga-Hunga Ha’apai volcano’s protracted, rumbling eruption spewing smoke and ash into the air, with a deafening roar heard 10,000 kilometers (6,000 miles) away in Alaska.
Saturday’s explosion was equivalent to a 5.8 magnitude earthquake at zero depth, according to the US Geological Survey.
However, with communication links down Sunday, the extent of the destruction in Tonga was unknown.
A 1.2-metre-high (four-foot-high) tsunami swept ashore in the Tongan capital Nuku’alofa, prompting residents to flee to higher ground, leaving behind flooded houses, some with structural damage, and small stones and ash dropping from the sky.
Scientist Marco Brenna of New Zealand, a senior lecturer at Otago University’s School of Geology, described the eruption’s impact as “very modest,” but added that future eruption with a far larger impact could not be ruled out.
Along Japan’s Pacific coast, waves up to 1.2 metres high were reported, with the Japan Meteorological Agency warning that waves as high as three metres were conceivable.
In New Zealand, about 2,300 kilometers from Tonga, 120 people were evacuated from northern coastal areas and several boats were wrecked as a massive wave slammed into a marina.
Bondi Beach in Sydney, Australia, was evacuated briefly as a precaution, while coastal streets in Santa Cruz, California, were inundated and blocked to traffic.
According to the National Weather Service Alaska, the Alaska Volcano Observatory detected the eruption in Anchorage and Fairbanks, which are located “6,000 miles from the volcano.”
After the explosions caused a spike in its air pressure graph, the Fife weather station in Scotland tweeted that it was “simply astounding to consider the strength that can send a shockwave around the world.”
Hunga-Tonga-Hunga-Ha’apai is located approximately 65 kilometers north of Nuku’alofa and has a turbulent past.
In recent years, it has broken sea level during a 2009 eruption and shot enough big rocks and ash into the air that when they settled, a new island two kilometers long, one kilometer broad, and 100 metres high developed.