ERUPTION OF THE HUNGA TONGA-HUNGA HA’APAI VOLCANO

On Saturday, late afternoon local time a huge explosive volcanic eruption occurred in the western Pacific Ocean in the Tonga Islands.

References : Szabolcs Harangi Blog

Satellite image of an ash cloud from Saturday’s volcanic eruption

According to satellite images, the volcanic ash cloud from the explosion rose to almost 20 kilometers and reached the stratosphere. The sound of the eruption was heard over 1000 kilometers away and the atmospheric pressure wave was felt all over the Earth. Following the eruption, flood alarms were triggered in the Tonga region thanks to indications from sensors built over the last decade. The tide flowed to the small islands in the region and during the day reached the west coast of Japan and even North America.

But what really happened and where is the volcano?

The Tonga region is about 1,500 kilometers north of New Zealand. The islands are of volcanic origin, as the Pacific Rock grows westward under the Australian rock. The consequence of this is that due to the high pressure and high temperature, wet solutions are released from the oceanic rock plate penetrating deeper into the rock plate. This is where the melting point of the earth’s rock is reduced, causing intense melting and core formation. When the magma surfaces, it causes volcanic activity.

However, this occurs underwater in most cases. Under the water cover of the ocean, smaller or larger volcanoes are formed, the growth of which can lead some of them to rise above the water and this is also what happened in the Tonga region. Under the water of the ocean, a huge volcano has formed, at the northern edge of which volcanic eruptions have created two smaller islands: the Hunga Ha’apai Islands and the Hongga Tonga Islands.

In 2015, an explosive volcanic eruption connected the two continents and after that they became an island. On December 20, after several years of calm, there was another huge explosive eruption in which the volcanic ash cloud rose to 15 kilometers high. With this, the size of the island increased again. Another rest followed, but not for too long! On January 14, there was an even more powerful explosion followed by another one a day later. The 21st competes in size with both. with the eruptions of the century.

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Tonga subduction (diving belt in rocky plate)

How can a small island produce such a volcanic eruption?

The underwater volcano of the ocean commands the authority, which was revealed by the research of the last decade. The eruption of the volcano rises to 1800 meters above the ocean surface and its base has a diameter of 20 kilometers. During their research seven years ago, by examining the rocks from previous eruptions of the volcano, volcanologists concluded that the volcano is capable of quite large eruptions.

What caused this massive explosion and why was the trench attached to it?

When the magma suddenly reaches the water-covered surface of the ocean, at the meeting surface of magma and cold water at more than 1000 degrees Celsius, a layer of steam develops, which explodes in a few seconds and the magma and water can mix. The water that enters the magma turns into steam, which causes a significant increase in volume. All this happens in a fraction of a second and the sudden increase in volume shatters the magma explosively, which breaks up at speeds of several hundred meters per second. The magma material erupts as a dark rooster-shaped cloud of volcanic ash, it is accompanied by a tiny eruption cloud rich in volcanic gases and water vapor. However, this eruption cloud has now rolled over 20 kilometers in altitude! Given the strength of the eruption, it is assumed that this was caused by the repression of a considerable amount of magma, which has already begun the extraction of gas bubbles, the mixture of magma and water gave only the final push for an explosive eruption. According to early satellite data, the eruption cloud reaching the stratosphere was not rich in sulfur dioxide, so the volcanic eruption is unlikely to have a climatic impact.

The sudden surge of huge amounts of magma during two large explosive eruptions caused the submarine volcanic surface to erupt, allowing the volcanic caldera to deepen and widen. This vertical movement of material triggered waves that caused flash floods on nearby islands and remote coasts of the Pacific Ocean.

Will there be a thousand years of calm following these two or three explosions in December?

It’s hard to say now, but volcanic analysis over the next few days will help interpret it. This volcanic activity also confirms the enormous role of satellite remote sensing devices in volcanological monitoring and eruption forecasting.

Eruption of the Hunga Tonga-Hunga Ha’apai volcano

But what really happened and where is the volcano?

How can a small island produce such a volcanic eruption?

What caused this massive explosion and why was the trench attached to it?

Will there be a thousand years of calm following these two or three explosions in December?

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