The Tonga volcanic eruption: What you need to know about this massive disaster13 min readReading Time: 8 minutes
This two-page story will take you through what happened on the island nation of Tonga On January 14 and 15. Don’t forget to read both pages for a clear understanding of the natural disaster. Click on ‘page 2’ at the bottom of the article. Happy reading!
Gray ash, all kinds of gases, hot steamy steam, giant waves, a sonic boom and plenty of lightening. An event more powerful than multiple nuclear attacks that has caused much damage occurred earlier this month. This scary, sinister-sounding occurrence is rare, the biggest of its type to take place in 30 years!
The occurrence we’re talking about isn’t something manmade nor is it supernatural or extra- terrestrial, but a massive underwater volcano that erupted in Tonga — a Polynesian nation — on January 14 and 15. Now, scientists at NASA say the tsunami that was caused by the powerful earthquake was hundreds of times more powerful than the atomic bomb the US dropped on Hiroshima in Japan during World War Two!
Let’s understand what exactly happened…
A massive underwater volcano erupted continuously in Tonga on January 14 and 15, triggering a deadly tsunami, covering islands in ash and knocking out local communications. Tsunamis also affected other countries around the Pacific Ocean, including Japan, the US, and Peru.
The volcano, known as ‘Hunga-Tonga-Hunga-Ha’apai’, erupted for about eight minutes, creating a spectacular plume of ash and volcanic debris that was even visible from space!
Tonga — an island nation composed of more than 170 islands in the South Pacific — has been covered in volcanic ash.
What is an undersea volcano?
An undersea or submarine volcano is located below the ocean surface and mostly erupts under water.There are an estimated one million undersea volcanoes that, like continental volcanoes, are located near the Earth’s tectonic plates and where they form. These volcanoes not only deposit lava, but can also spew out large amounts of volcanic ash.
Owliver’s Obscure Observation
According to experts, about three-quarters of all volcanic activity on Earth actually occurs underwater. Undersea volcanic activities give rise to seamounts – underwater mountains that are formed on the ocean floor but do not reach the water surface.
How often does this volcano erupt?
The Hunga-Tonga-Hunga-Ha’apai volcano, which lies about 65km north of the capital of Nuku’alofa, has a history of volatility. This essentially means that this volcano has always kept people on their toes.
In recent years, the Hunga-Tonga-Hunga-Ha’apai breached sea level during a 2009 eruption. In another eruption in 2015, it spewed so many large rocks and ash into the air, it caused a new island to be formed!
On December 20 last year and then on January 13, the volcano erupted again, and on January 15, another massive eruption occurred, triggering a tsunami around the Pacific.
Massive waves in many countries
Undersea volcano eruptions can lead to tsunamis, which are a series of ocean waves caused by the displacement of water. However, the exact cause behind these tsunamis are debatable. Scientists say that the tsunamis that formed after this recent eruption could be due to a part of the volcano breaking off, an explosion underwater, or a combination of both. Typically, tsunamis are triggered by earthquakes more than they are by volcanoes.
The waves from this tsunami reached a height of 2 metres in Tonga and other Pacific Islands, wiping away some settlements and houses. The tsunami radiated across the Pacific, hitting the coasts of Australia, New Zealand, and Japan with waves over a metre high. It also hit the west coast of the Americas, causing flooding in North America. It caused more damage in South America with the coasts of Chile, Ecuador, and Peru experiencing high waves.
Shockwaves seen from space!
The explosive eruption produced a shockwave that was clearly observable on satellite images. This shockwave travelled across the globe at the speed of sound, and was recorded around the world as both a pressure wave and an acoustic signal.
Most instruments globally recorded the shockwave twice, one from the direction closest to Tonga, and the other from the opposite direction, due to the part of the wave emanating from the other side of Tonga.
The accompanying sonic boom was recorded in many places, and reached Alaska, over 9,300 km away, after seven hours. It travelled around the world twice, converging in Algeria before radiating to Tonga and back again.
Tallest ash column
The eruption also produced possibly the tallest-known ash column of an eruptive volcano. When volcanic activity began on December 20, the ash being emitted from the vent climbed up 16km into the atmosphere. On January 14, after the eruption, the ash column rose up a further 10km.
Some early calculations show that the ultimate height the ash reached directly from the volcano was 39km. If this number is confirmed, this is the highest that a cloud from a volcano has reached.
Owliver’s Obscure Observations
Tonga is the only kingdom in the Pacific since Taufa’ahau (King George) in 1875 declared Tonga a constitutional monarchy, he also gave Tonga its first constitution.
Volcanic emissions can inject large amounts of sulphur dioxide (SO2) into the atmosphere, which can act as a global coolant. However, initial data suggests that the amount of SO2 released is not enough to cause any significant impact on global climate.
Ash fall from volcanic eruptions can cause extensive environmental damage and crop failure. Currently, in Tonga and on other Pacific Islands, there is a thick layer of ash deposited on everything. This ash mixes with soil, making it more acidic. The ash can also lead to acid rain, which could damage crops.
An electric storm
The volcano set off a powerful electric storm in the ash cloud. Electric storms generate lightning strikes, which are common in volcanic eruptions when ash is climbing up into the skies. Particles of dust and ash rub against each other producing static electricity, isolating positive and negative charges, and discharging lightning.
As the ash climbs even higher into the colder parts of the atmosphere, particles start to rub against ice crystals, amplifying the effect. When an eruptive event is intensified because of contact with water, the ash produced is even finer, leading to more particles causing more electric discharges.
Tonga’s lightning flashes were detected by the Global Lightning Detection network, and it recorded the expected hundred to thousands of flashes a day. But, at the peak of the January event, it detected 200,000 discharges an hour. Over 400,000 lightning events were ultimately recorded in a matter of three hours. The strikes also hit the unoccupied ground and waters in the area.