The powerful eruption of an undersea volcano near the Tonga islands took place in the Pacific ‘Ring of Fire’, where 75 percent of the world’s volcanoes lie.
Tonga remains cut off from the world two days after an underwater volcano erupted and triggered tsunami alerts across the Pacific, including in Samoa, Australia, Japan, Hawaii, Chile and the US Pacific coast.
On January 15, the Hunga Tonga-Hunga Ha’apai volcano, about 70 km northwest of the nation’s capital Nuku’alofa, sent plumes of smoke 20 km into the air and wrought significant damage across the South Pacific nation’s western coastline.
The eruption triggered a tsunami on its shores and cut off phone and internet lines for the entire island.
Tonga comprises 169 islands, 36 of which are inhabited, and has a population of around 105,000 people.
Data so far suggests it was the biggest eruption since Mount Pinatubo in the Philippines over 30 years ago, while some have called it the “most energetic explosions in the entire 21st century”.
Hunga Tonga-Hunga Ha’apai has repeatedly erupted over the last few decades, but the impact of Saturday’s eruption was felt as far away as New Zealand, Fiji, the US and Japan.
Volcanoes are a common occurrence along the boundaries of Earth’s tectonic plates.
Since many of these plates are submerged, underground volcanic eruptions account for approximately three-quarters of all volcanic activity on Earth.
Even though most submarine volcanoes do not produce the spectacular eruption events of some of their land counterparts, undersea volcanic activity is a constant process that shapes the features of the ocean – from magma and ‘pillow lava’ forming much of the oceanic crust, to the formation of new seafloors.
Where are most of the world’s volcanoes and how many active ones are there?
The US has 165 Holocene (historically active) volcanoes, with 64 of them active over the last 200 years.
Indonesia follows next with 124 Holocene volcanoes, Japan and Russia have 122 and 117 respectively, and Chile rounds out the top five with 95.
As of December 2021, there are at least 46 volcanoes that are currently erupting. An eruption described as “continuing” does not always mean persistent daily activity, but indicates at least intermittent eruptive events without a break of 3 months or more.
In total, 74 volcanoes erupted over the course of 2021.
There are about one million undersea volcanoes – most of which are extinct.
According to the US Geological Survey, there are around 1,350 potentially active volcanoes globally. Most of them are located along a 40,000 km arc along the Pacific in an area known as the “Ring of Fire”, where 75 percent of the world’s volcanoes and 90 percent of all earthquakes occur.
All of Tonga’s volcanoes are located along the Ring of Fire.
What are the deadliest eruptions of the 21st century?
An unexpected blast caused by a collapse of a lava dome in early December at Indonesia’s Semeru killed at least 43 people when ash fall and pyroclastic flows rained down and buried some villages around the volcano.
DR Congo (2021)
Nyiragongo, DR Congo’s most active volcano, saw lava flows from new fissures that destroyed hundreds of buildings and killed dozens. Its continued volcanic activity prompted the government to evacuate 400,000 people in June before they returned some days later.
The Philippines’ second-most active volcano, Taal in Batangas province, erupted in January and displaced over 376,000 people from surrounding towns. 39 people died in evacuation centres, scores of livestock perished and 135,000 people were put in shelters.
New Zealand (2019)
Whakaari/White Island, an active volcano island in New Zealand’s Bay of Plenty region, erupted in December when 47 people were visiting the island at the time. 22 ended up dying and 25 were injured.
The dramatic collapse of the Anak Krakatau volcano in December triggered a devastating tsunami which inundated the coastlines of Java and Sumatra and led to the deaths of more than 400 people.
Guatemala's Fuego volcano erupted in June and killed almost 100 people. Ash fall extended as far as the capital, Guatemala City, forcing the closure of the country’s international airport.
The sudden eruption of Mount Ontake killed more than 60 people in Japan’s worst volcanic disaster in nearly a century. The 3,067 metre Ontake was packed with hikers when it erupted without warning.
An eruption occurred at Mount Sinabung, which lay dormant for 400 years before it roared back to life in February on the island of Sumatra and killed 16 people.
Mount Merapi, known as one of the world’s most dangerous volcanoes, exploded on central Java, killing over 300 people and saw 280,000 evacuated after its most powerful eruption since 1872.
DR Congo (2002)
Nyiragongo erupted and destroyed the centre of Goma town, killing more than 100 people.