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Geological Catastrophs:
Connections of Volcanos, Floods and Climate Change(s) 

Occasionally, geological events change the climate. These changes typically last only for while but their duration varies in dependence of the causing event. For example: 

A volcanic eruption can cause an explosion of a mountain top that

  1. changes the skyline of the landscape as well as the lava rivers reshape the landscape and causes hot stonish material heating up the water,

  2. blows solid material (sand, dust, stone) into the higher atmosphere,

  3. and the pressure of the explosion causes seismic waves on land and tsunami waves in the sea. 

This way, the volcano causes several geological catastrophs: 

  1. a change of the geological formation, e.g. raise and vanishing of islands 

  2. clouds that travel around the Earth in the higher atmosphere. If these clouds are whitish clouds of sulfur oxides, they reflect much more light from the Sun directly into space so that it cannot reach the ground which has a cooling effect on Earth. If these clouds are dark clouds of dirty material, they also block the sunlight. Additionally, the emitted toxic material from below the Earth is distributed over large distances on Earth and affects life.  

  3. the pressure waves can cause earthquakes and floods. 

Historic Eruption of Krakatoa 1883

The eruption of Krakatoa in 1883 has been one of the strongest known in history.

The successive change of the geological formations, the creating and distruction of islands by volcanic activity is shown in the animated GIF; contributed to WikiCommons by users Morn and Sémhur. 


Lithograph: Parker & Coward, Britain. Plate 1 in The eruption of Krakatoa, and subsequent phenomena. Report of the Krakatoa Committee of the Royal Society (London, Trubner & Co., 1888).


Hunga Tonga eruption Jan. 2022

This is currently the highest eruption of a volcano recorded by satellites: The cloud was 58 km high and it consisted of ashes, water, and (toxic) sulfur oxids and the day after the eruption, this ash plume covered a territory on Earth that was as big as Germany and France together (i.e. as big as whole central Europe). The sulfur oxids have a whitish colour which reflects a lot of sunlight, so below this cloud it is rather dark for the whole day. 
Within the cloud, there are electric discharges observed as thunderbolts and lightning. 

At a height of 30 km, the volcanic ash cloud is much higher than aeroplanes and normal rain and thunder clouds, and the material is carried by the winds in these higher layers of the atmosphere. The material is distributed by the winds and it can take several orbits until the material is slow enough to sink in the atmosphere and fall back to Earth.

The graphics on the right hand side shows the air pressure wave detected in Germany on the evening of the eruption. In fact, the wave was detected twice in central Europe: On the evening of the 15th of January, this wave was detected because the pressure wave from the South Pacific hit Europe directly. A quarter of a day later, in the early morning of the 16th of January, the wave was detected again because it had traveled around the complete globe in the meantime. The second pressure wave, of course, was not as big as the first one but still easily recognizable.  

The wave of air pressure detected in central Europe after the eruption in the South Pacific. The map displays the pressure gradient in the air within 10 min.

Apart from the direct shockwaves of air and water that travelled around the Earth directly after the eruption and caused floods in Australia, New Zealand, and Japan, the huge amount of water blown into the stratosphere also caused a climate change. Due to the wind cells on Earth, the water in the higher atmosphere above the South Pacific is carried southwards and cools above Antarctica by one to three degrees Celcius. As cooler air and water falls down, this caused massive rains and floods in Australia throughout the whole year of 2002 (after the strong eruptions in January).   

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