A supervolcano is classed as more than 500 cubic kilometers of erupted magma volume, and is 500 times larger than a typical volcano. Knowledge of triggering mechanisms is crucial for monitoring supervolcano systems. A new study has revealed that supervolcanoes with massive eruptions with potential global consequences become active when the roof above them cracks or collapses, not because of internal pressure building.
Lead researcher Patricia Gregg, professor of geology at University of Illinois, said, "If we want to monitor supervolcanoes to determine if one is progressing toward eruption, we need better understanding of what triggers a supereruption. It is very likely that supereruptions must be triggered by an external mechanism and not an internal mechanism, which makes them very different from the typical, smaller volcanoes that we monitor."
‘Until now researchers thought that the pressure in the magma chamber increases until it causes an explosion and the volcano erupts. But, a new study has revealed that supervolcanoes become active when the roof above them cracks or collapses, not because of internal pressure building.’
Gregg further added, "Typically, when we think about how a volcanic eruption is triggered, we are taught that the pressure in the magma chamber increases until it causes an explosion and the volcano erupts. This is the prevailing hypothesis for how eruptions are triggered. At supervolcanic sites, however, we do not see a lot of evidence for pressurization."
According to the new model that the research teams developed, if a crack or fault in the roof penetrates the magma chamber, the magma uses the crack as a vent to shoot to the surface. This could trigger a chain reaction that 'unzips' the whole supervolcano.
The study was published in the Journal of Volcanology and Geothermal Research.