Tonga Volcano Eruption-An undersea volcano called Hunga Tonga-Hunga Ha’apai erupted recently in the Kingdom of Tonga.
About Tonga Volcanic Eruption:
- Tonga Volcano eruptionis an Undersea Volcanic Eruption consisting of two small uninhabited islands, Hunga-Ha’apai and Hunga-Tonga.
- The Hunga-Tonga-Hunga-Ha’apai volcano has erupted regularly over the past few decades.
- During events in 2009 and 2014/15, hot jets of magma and steam exploded through the waves. But these eruptions were small, dwarfed in scale by the January 2022 events.
- This is one of the massive explosions the volcano is capable of producing roughly every thousand years.
- The type of Plate Boundary interaction is a Convergent type interaction.
- The two plates involved are the Australian plate(Continental) and Pacific Plate(Ocean).
- The majority of volcanic arcs can be found in the Ring of Fire, a horseshoe-shaped string of about 425 volcanoes that edges the Pacific Ocean.
- The 2014/15 eruption in the Tonga volcano created a volcanic cone, joining the two old Hunga islands to create a combined island about 5km long.
- Mapping the sea floor, it was discovered a hidden ‘caldera’ 150m below the waves.
- The caldera is a crater-like depression around 5km across
- A caldera is a large depression formed when a volcano erupts and collapses. During a volcanic eruption, magma present in the magma chamberunderneath the volcano is expelled, often forcefully. When the magma chamber empties, the support that the magma had provided inside the chamber disappears. As a result, the sides and top of the volcano collapse inward.
Why are Tonga volcano’s eruptions so highly explosive?
- If magma rises into sea water slowly, even at temperatures of about 1200 degrees Celsius, a thin film of steam forms between the magma and water. This provides a layer of insulation to allow the outer surface of the magma to cool.
- But this process doesn’t work when magma is blasted out of the ground full of volcanic gas. When magma enters the water rapidly, any steam layers are quickly disrupted, bringing hot magma in direct contact with cold water.
- Research into these earlier eruptions suggests this is one of the massive explosions the volcano is capable of producing roughly every thousand years.
- Volcano researchers call this ‘fuel-coolant interaction’ and it is akin to weapons-grade chemical explosions. Extremely violent blasts tear the magma apart. A chain reaction begins, with new magma fragments exposing fresh hot interior surfaces to water, and the explosions repeat, ultimately jetting out volcanic particles and causing blasts with supersonic speeds.