Archive – Tonga volcano explosion – NOAA AND THE NATIONAL ENVIRONMENTAL SATELLITE
MADRID, May 9. (EUROPA PRESS) –
A study published in the Journal of Volcanology and Geothermal Research offers an alternative mechanism that triggered the historic eruption of the Hunga volcano in Tonga on January 15, 2022,
The research proposes that the powerful eruption was caused by a gas-driven climatic explosion rather than a phreatomagmatic one, where magma and water react violently through the water column.
Led by the Australian National University (ANU) in collaboration with GNS Science, the study presents a new evidence-based model that describes how the formation of a gas seal led to the accumulation and release of enough explosive energy in a matter of minutes to forming a 58 km high ash column, a crater deeper than the Burj Khalifa Tower (Dubai) and high atmospheric shock waves that enacted the entire planet.
The authors argue that a gas-driven trigger is likely based on the magnitude of the eruption, the temporal sequence of the event, the massive amounts of volcanic gas release, the remaining structure of the volcano, and the presence of minerals formed through interactions of magmatic gas with the surrounding rock (e.g. sulfate minerals).
For an underwater volcano to release enough energy through the water column to create this immense column, as well as a globally felt burst of atmospheric air, It would take a colossal amount of force, similar to or even greater than that of the 1883 Krakatoa eruption.
“Our model describes a process that explains how the accumulation of volcanic gases during the previous months to the eruption could generate this scale of explosive energy,” said author Richard Henley, from the ANU School of Physics.
The article puts forward the following hypothesis about the eruption sequence: a fluctuation of reactive gases derived from magma aggressively alters the rocks in the core of the volcano, this reaction creates a seal that blocks the flow of gas to the surface, the internal pressure of the gas increases and puts pressure on the volcanic structure, the seal fractures and leads to an explosive release of compressed gasthe crater enlarges and the deepening allows an uncontrolled gas explosion by releasing gas at increasingly higher pressure from the porous rock mass, the eruption slows as the compressed gas is depleted and seawater fills the crater .
The proposed model is further supported by a numerical model which calculates that the potential energy of the trapped compressed gas matches independent observations of the scale of the eruption.
“The paper not only suggests that Tonga’s plinean eruption was driven by gas, but proposes that this mechanism may be characteristic of all plinean eruptions, regardless of whether the volcano is oceanic or subaerial. If correct, a pause in the gas discharge can act as a precursor to a major eruption,” Henley said it’s a statement.
