On January 15, an underwater volcano in the South Pacific erupted violently that triggered tsunami waves around the Pacific and caused “significant damage” to the island nation’s capital and smothered it in dust, but the full extent was not apparent with communications still cut off on January 16.
About the occurrence:
The underwater eruption was so powerful that it was recorded around the world, triggering a tsunami that flooded Pacific coastlines from Japan to the United States.
The capital Nuku’alofa suffered “significant” damage, New Zealand Prime Minister Jacinda Ardern said, adding there had been no reports of injury or death but a full assessment was not yet possible with communication lines down.
The Fife weather station in Scotland tweeted it was “just incredible to think of the power that can send a shockwave around the world” after the eruptions produced a jump in its air pressure graph.
At the same time, dramatic satellite images showed the long, rumbling eruption of the Hunga Tonga-Hunga Ha’apai volcano spew smoke and ash in the air, with a thunderous roar heard 10,000 kilometres (6,000 miles) away in Alaska.
The US Geological Survey recorded the eruption as equivalent to a 5.8 magnitude earthquake at zero depth.
Besides, a 1.2 metre (four-foot) swept the wave shorewards in the Tongan capital Nuku’alofa with locals reporting they had fled to higher ground, leaving behind flooded houses, some with structural damage, and with small stones and ash falling from the sky.
Scientist describes impact of the eruption:
A scientist from New Zealand Marco Brenna who is a senior lecturer at Otago University’s School of Geology, described the impact of the eruption as “relatively mild” but said another eruption with a much bigger impact could not be ruled out. In New Zealand, more than 2,300 kilometres from Tonga, 120 people were evacuated from northern coastal areas and several boats destroyed when a huge wave crashed into a marina.
While Australia’s popular Bondi Beach in Sydney was briefly evacuated as a precaution while in California, coastal streets in Santa Cruz were awash and closed to traffic, the National Weather Service Alaska reported the Alaska Volcano Observatory had recorded the eruption in Anchorage and Fairbanks “6,000 miles from the volcano.”
The Fife weather station in Scotland tweeted it was “just incredible to think of the power that can send a shockwave around the world” after the eruptions produced a jump in its air pressure graph.
Hunga-Tonga-Hunga-Ha’apai, which lies about 65 kilometres north of Nuku’alofa, has a history of volatility. It surpassed sea level during a 2009 eruption while in 2015 it spewed so many large rocks and ash into the air that when they settled a new island had formed two kilometres long by one kilometre wide and 100 metres high.
About Submarine Volcanoes:
Eruptions from submarine volcanoes can pose hazards to both passing boats and populations nearby. Lodolo cautions that more study is needed to better understand potential risks from the newfound structures, and other geologists agree that any hazards are likely minimal.
The volcanoes are not especially tall, comparatively speaking, rising between 52 and 350 feet from the seafloor. But because they sit inside the shallow channel, their tops are not very deep; Actea’s peak is the shallowest at just 110 feet down.
Submarine volcanic eruptions are characteristic of the rift zones where crustal plates are being formed. These rift zones, which are found in all of the Earth’s major ocean basins, are known as seafloor spreading centers because they are places where tectonic plates are moving away from each other. Most seafloor spreading centers lie at depths exceeding 2,000 meters (1.2, miles) and, as a consequence, approximately three-quarters of all volcanic activity on Earth occurs as deep, underwater eruptions. The effects of these deep eruptions cannot be seen from the surface of the ocean.
