A technique presented in Nature Communications by researchers from the National Oceanography Centre Southampton (NOCS) and the University of Southampton will aid in predicting the dispersal and drift patterns of large floating “islands” of pumice created by volcanic eruptions at sea.
Known as pumice rafts, these large mobile accumulations of pumice fragments can spread to affect a considerable area of the ocean, damaging vessels and disrupting shipping routes for months or even years. The ability to predict where these rafts will end up could give enough advance warning for protective measures to be put in place on shipping routes or in harbours where the presence of pumice is hazardous.
Reproducing Surface Drift
Martin Jutzeler, Post-Doctoral Research Fellow at NOCS, and a team of colleagues simulated the drift of a massive 400 km2 raft of pumice from Havre, a deep submarine volcano in the southwest Pacific, using a high-resolution model of the global ocean circulation.
The team, which included researchers from the University of Tasmania in Australia, the University of Otago in New Zealand and Stanford University in the United States, then tested the results against satellite imagery plus direct observations from sailing crews, to show that they can accurately reproduce surface drift using this method and note that this large-scale natural experiment validates the physics of the model.
Forecast Dispersal Routes
This technique, they believe, can be used to forecast dispersal routes of potentially hazardous pumice rafts from future eruptions, mitigating potential risks to ships and allowing authorities to protect harbours. The same high-fidelity particle tracking can also be used to predict the spread of other floating objects in surface ocean waters, such as anthropogenic waste or passively-drifting organisms.
The paper ‘On the fate of pumice rafts formed during the 2012 Havre submarine eruption’ is published online by Nature Communications.
Picture: Sequential motion of pumice rafts from MODIS images in the first 3 weeks after the eruption.
