The classic theory about how volcanic eruptions occur has been essentially disproven. The dominant theory of the last quarter century asserts that “mantle plumes,” driven by the heat of the molten core, shoot up into the world and create new volcanic eruptions.

A joint research project by Caltech and Miami University sought to figure out exactly what was going on by analysing years of global seismic data. They sought to either confirm, or finally falsify, the “lava lamp theory” of mantle plumes. What they found was actually the opposite of their expectations!

Don Anderson, professor emeritus for geophysics at Caltech, was lead researcher in the project. Instead of finding mantle plumes, they found massive magma upwellings that were thousands of kilometers across.

Instead of the warmer material being pushed up from the depths of the core, it turns out that colder material from the crust “falls” down and pushes the warmer magma up in its wake. Instead of the lava lamp, picture instead a pond: when a rock falls to the bottom it also propels pieces of the bottom to the surface. Although pieces of existing volcanic theory, such as plate tectonics, remain unadulterated. The paradigm shift centers around the fact that the magma comes from within the upper 200 kilometers of the mantle instead of from 1000s of kilometeres deep (as the mantle-plume theory suggested).

This changes some of the theories dealing with rock formation and composition. Instead of magma coming from thousands of kilometers deep and mixing with isolated pockets closer to the surface, we now have to come to terms with the fact that huge bodies of lava simply sit relatively close to the surface before spewing out into our world. This serves as yet another reminder that science is not perfect, but continues to find its way closer to the truth by ruling out possibilities.