some Volcanoes They violently expel magma while others release, although they contain huge amounts of gas, without the process turning into a devastating explosion. The difference depends on the way it is done The movement of magma within the conduit and how quickly gases escape before reaching the surface.
When the internal flow of magma allows gas to be released little by little, the mountain behaves more stably. This internal balance explains why one eruption can turn into a simple lava flow while another eruption with a similar composition turns into a simple lava flow. It destroys everything around it.
Differences in the way gas is released explain the behavior of volcanoes
A study published in the journal sciences The physical mechanism that regulates this variation has been identified. According to the international team led by Olivier Bachmannfrom the Federal Institute of Technology Zurich (ETH Zurich). Shear forces Within volcanic channels, they are internal frictions that arise when different layers of magma move at different speeds, causing Early formation of gas bubbles Which relieves the pressure of the magma before it reaches explosive levels.
“We can explain why some viscous magma flows smoothly rather than erupting, despite its high gas content,” Bachmann said. This discovery illustrates a phenomenon that has puzzled modern volcanology for decades.
The researchers demonstrated this process in the laboratory using a viscous liquid saturated with carbon dioxide that mimics the behavior of lava. When it was activated, they noticed that Shear stress generated bubbles without the need for pressure reduction. “The movement of magma due to shear forces is sufficient to form gas bubbles, even without a pressure drop,” Bachmann explained.
At the edges of the material, where friction is greatest Bubbles appeared in a seriesThe initial gas density determined the ease of the process. The researcher added, “The more gas the magma contains, the less shear stress is needed for bubbles to appear and grow.” Computer simulations confirmed that The phenomenon is repeated inside real volcanoesEspecially in areas where viscous magma intensely rubs against the canal walls.
The comparison with honey helps to understand how gas channels are formed
The operation of this mechanism can be compared to what happens when a thick liquid, such as honey, is stirred in a bowl. The center flows more freely, while the edges slow down and generate friction. Inside a volcano, magma behaves in a similar way: It moves quickly through the central part and stops near the wallsThis creates speed differences that cause shear.
This internal friction acts as an additional source of energy, supporting the nucleation of gases at depth. the The bubbles clump together and form channels through which the gas gradually rises and escapes.This reduces the possibility of violent energy release.
He has the discovery Important consequences for volcanic hazard assessment. Traditional models have focused almost entirely on pressure loss as magma rises, an approach that does not explain why some volcanoes with very gaseous magma produce quiet eruptions.
With new evidence, researchers It is recommended to include the influence of shear forces In risk calculations, Bachmann emphasized that “to better predict potential volcanic hazards, We must update the models and incorporating shear forces into the channels. This improvement will allow us to understand and provide why mountains with similar properties behave so differently More reliable tools for predicting when a volcano will release its energy quietly and when it might do so violently.