All this time, geologists thought a volcanic eruption was a ‘bang’ event, only to find out what is happening is actually more akin to ‘squeezing.’ At least that’s what a new study from Imperial College London and the University of Bristol is proposing.

Our Understanding Of Volcanoes Was Wrong

The magma chamber model has been the dominant and widely taught theory about the inner workings of a volcano. The model states that underneath every volcano is a great big chamber full of liquid magma. Using this model, scientists had come to understand (or so they thought) how and why volcanoes erupt, and why some erupt and some are dormant. The theory aligns well with all the indirect evidence they had gathered based on things like geophysical readings and pre-eruption events which can be seen from the surface only. The only real issue was that they could never seem to find many large magma chambers.

This new study posits that volcanoes are instead fed by what are called ‘mush reservoirs.’ Mush Reservoirs are areas that contain primarily solid crystals, and magma flows in the small pockets between the crystals. With this theory, scientists now need to understand how a mush reservoir could cause an eruption, and why that would happen. Understanding volcanic eruptions is closely tied to public safety, as predicting a volcanic event before it actually happens will allow people to evacuate and minimize the lives lost.

The Inner Workings Of A Volcano

Volcanoes need flowing magma to erupt. In order for magma to flow, scientists always thought very few crystals could be present. That’s why the molten magma chambers seemed to explain volcanic eruptions. Keep in mind that no human has actually ever laid eyes on one of these chambers. It was all speculation. The magma chemistry analyses in the new study have now challenged this theory.

It turns out, such a large magma chamber does not seem to be necessary after all. The small pools of magma formed between gaps in the crystals indicate that the mush reservoir model is more likely. The research team made a digital model of a mush reservoir to test if and how it would function. This is how they think it works. The magma rises through the crevices between the crystals, as the crystals themselves are too dense to pass through. In this process, the magma and crystals form a chemical reaction that starts to melt the crystals, resulting in areas that don’t have very many crystals.

It turns out that magma passing through the crevices between crystals is what leads to eruptions. Molten rock takes formation inside of mostly crystalline hot rocks. Instead of residing in large magma chambers as previously believed, it actually resides in the rocks’ pores. Slowly, the rock melt gets squeezed out, forming pools of melt, and can cause eruption as well as temporary magma chambers.

This New Model Makes More Sense To Geologists

Geogists used to get confused about certain volcanic phenomena, because much of it didn’t fit with the molten magma chamber theory. On the contrary, the mush reservoir theory makes sense with lots of known volcanic phenomena. Take for example the way magma’s chemical composition transforms over time or finding ancient crystals in new magma. That is quite promising in the world of volcanic research.

Only further studies can solidify the mush reservoir theory, but it seems inevitable that it will become the dominant model for understanding how volcanoes function.