Hunga-Tonga Volcano

11th September, 2023 Geography

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Context

These "density currents", as they're known, snapped long sections of telecommunications cabling, cutting the Pacific kingdom's link to the global internet.
They also smothered and killed all sea life in their path.

Details

The Tonga Islands are located along the Ring of Fire, which encircles the Pacific Ocean basin and is characterized by increased volcanic and seismic activity.
It's an Undersea Volcanic Eruption made up of two small deserted islands called Hunga-Ha'apai and Hunga-Tonga.
Over the last few decades, the Hunga-Tonga-Hunga-Ha'apai volcano has erupted regularly.
Hot jets of magma and steam erupted through the seas during events in 2009 and 2014/15. However, these eruptions were minor in comparison to the January 2022 occurrences.
This is one of the huge explosions that the volcano can produce every thousand years.
The Fuel-Coolant interaction is one of the reasons it is highly explosive.

Impact

Large volcanic eruptions can occasionally induce brief global cooling by releasing sulfur dioxide into the stratosphere.
However, in the case of the Tonga eruption, preliminary satellite data indicated that the amount of sulfur dioxide produced would have only a negligible influence on global average cooling of perhaps 0.01 degrees Celsius.

Volcano

A volcano is a hole or rupture in the earth's surface that allows magma to escape as hot liquid and semi-liquid rock, as well as volcanic ash and gases.
Volcanic hotspots are areas on Earth's surface where tectonic plates collide.
A volcanic eruption is the outpouring of lava and gas from a volcano, which can be explosive.

Underwater Volcano

The undersea volcanic eruption occurs in a volcano lying beneath the ocean's surface.
There are around one million undersea volcanoes, the majority of which are found near tectonic plates.
In addition to lava, these vents discharge ash.
These settle on the ocean floor, resulting in the construction of sea mounds, which are underwater mountains that build on the ocean floor but do not reach the water's surface.

Interaction of Fuel and Coolant

When magma slowly rises into seawater, even at temperatures of 1200 degrees Celsius, a thin layer of steam occurs between the magma and the water.
This acts as an insulator, allowing the magma's outer surface to cool. However, when magma containing volcanic gas is blasted out of the ground, this process fails.
When magma rapidly meets water, any steam layers are soon destroyed, putting hot magma into direct contact with cold water.
It's comparable to weapons-grade chemical explosions.
The magma is ripped apart by extremely powerful blasts.
A chain reaction ensues, with new magma fragments exposing fresh hot inner surfaces to water, and the explosions continue, eventually jetting out volcanic particles and creating supersonic bursts.

About Hunga-Tonga Volcano

Tonga's Hunga Tonga-Hunga Haapai is a volcanic island.
It is around 30 kilometers south of Fonuafoou's undersea volcano and 65 kilometers north of Tongatapu, the country's major island.
The volcano is part of the highly active Tonga-Kermadec Islands volcanic arc, a subduction zone that runs north-northeast from New Zealand to Fiji.
The convergent boundary where the Pacific Plate subducts beneath the Indo-Australian Plate forms the island arc.
It is located in the western South Pacific Ocean, alongside the caldera rim of a much larger undersea edifice.
Over the last few decades, it has erupted regularly.

PRACTICE QUESTION

Mention the global occurrence of volcanic eruptions in 2023, as well as the effects on the regional ecosystem.

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