A computational approach which links processes deep below a volcano to potential eruptions is described by researchers at the University of Bristol in a paper published today in the Journal of Geophysical Research. The research could ultimately help scientists to understand magma chamber processes and volcanic eruption timing.
Violent volcanic eruptions can lead to collapse of the solid lid above the drained magma reservoir and create a depression called a caldera. Such caldera-forming eruptions are among the most devastating natural processes on Earth, threatening not only nearby settlements but also impacting upon the global climate.
The study by PhD student Anne Schöpa and Dr Catherine Annen in Bristol’s School of Earth Sciences shows that magma chambers required for caldera-forming eruptions might grow faster and with less initial magma input than previously thought, making the forecast of volcanic eruptions more problematic.
Anne Schöpa said: “It was previously believed that a gradual increase in the magma input could form a large magma chamber which is necessary prior to a big caldera-forming eruption. However, our numerical heat flow models show that this is quite difficult with a continuously rising magma influx.
“Instead, the magma input has to increase drastically and almost instantaneously above the background magma flux in order to create a big magma reservoir. This increases the difficulty of making volcanic eruption forecasts because precursors of an eruption such as ground deformation would be detectable just shortly before an eruption.”
This investigation utilised computer based modelling simulations to provide information on the intrusion rates, with model constraints coming from recent dating of granite intrusions, thought to be the remnants of non-erupted magma.
Anne Schöpa continued: “We wanted to test whether large magma chambers can form during the construction of crustal intrusions. However our study shows that only very specific conditions of magma recharge lead to large reservoirs of molten magma and more often than actually erupting, the magma remains in the crust and freezes becoming a granite intrusion like those exposed in Dartmoor and Cornwall.”
Source: University of Bristol