Hazards and risks from volcanic ash

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Johanne Schmith


DKK 850,000




Internationalisation Fellowships


Why does a volcano start to erupt violent plumes of volcanic ash and who will be affected? This question became vital for the inhabitants of the island of Hawaii, USA, as a several km high ash plume rose from the summit of Kīlauea volcano on May 17th 2018. My project addresses the issue by studying layers of ash formed at Kīlauea in the past and build on a record of hundreds of years of explosive eruptions. I am using the physical characteristics of the ash to study the explosive processes. The findings will be used to forecast future eruption scenarios and the associated hazards. The final results will be integrated with new communication strategies at the Hawaiian Volcano Observatory to ensure local impact of the study, and to reach the people, whose lives and livelihoods are at risk.


Volcanic ash is the most widespread of all volcanic hazards. It can cause respiratory problems, clog air filters, cause jet engine damage/shutdown in airplanes, block and contaminate water supplies, and adversely affect agriculture and transportation. However, basaltic volcanoes such as Kīlauea are known for their lava flows, and were not thought to produce ash plumes of notable size. Therefore information about ash generating eruptions is lacking in hazard evaluations of volcanoes like Kīlauea. Recent studies have shown the assumption to be wrong and reveal a significant gap in our understanding of the behavior of basaltic volcanoes. My research serves to fill this knowledge gap and also inform hazard models to help crisis management prepare for explosive eruption scenarios at Kīlauea.


My study uses a combination of field observations, laboratory measurements and computer modelling. My fieldwork is carried out on the summit of Kīlauea, where meters of ash covers the ground in many places. I am tracing the ash deposits across the entire area, noting thickness, structure, and the type of ash, it contains. I collect ash samples, which go into my lab for measurements of size, shape, density, and grain type, and finally I feed the data into computer models to achieve mathematical parameters describing the size and dynamics of the eruptions. I also use the grain size and -shape to model how the explosions happened. My parameters and ash maps are used to forecast the eruption dynamics and distribution of ash of future explosive eruptions, and present it as a hazard map.

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