Source: Massey University
Concurrent with these experimental findings, pyroclastic surges generated during the Whakaari eruption killed 22 visitors to the island and severely injured another 25, marking it as the deadliest eruption in Aotearoa New Zealand since the 1886 eruption of Mount Tarawera.
“Working on the eruption data, we realised that pyroclastic surges, during their runout, had engulfed an array of pressure sensors that usually monitors explosion signals from within the volcano and its vent system. The characteristics of the pressure signals inside the Whakaari surges were the same as in our experimental flows, just that instead of 75 pressure pulses per minute in our experiments, the natural surges showed 12 such pulses per minute,” Dr Brosch says.
The researchers showed that the hazardous pulsing inside pyroclastic surges occurs because the flow energy focusses into and is transported within the largest turbulent eddy structures. They developed a new flow model that allows prediction of these pulses in future volcanic events. This discovery, which is also applicable to snow avalanches, necessitates a re-evaluation of volcanic hazard models that aim to forecast and mitigate volcanic impacts here in New Zealand and elsewhere.
This research was partially supported by a Royal Society Marsden Fund grant), a Ministry of Business, Innovation and Employment Endeavour Research program, and a Resilience to Nature’s Challenges Science Challenge Fund.
The article, Destructiveness of pyroclastic surges controlled by turbulent fluctuations, was recently published with open access in Nature Communications.
Authors includes Dr Eric C.P. Breard and Professor Joseph Dufek of the University of Oregon, USA; Dr Tomaso Esposti-Ongaro and Dr Matteo Cerminara of the Istituto Nazionale di Geofisica e Vulcanologia, Pisa, Italy; Dr Betty Sovilla of WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland, and Dr Luke Fullard of the School of Fundamental Sciences, Massey University.
