A volcano on remote Marion Island may erupt within weeks, according to a study published on Sunday that identifies a rapid build-up of magma beneath the South African territory. Researchers estimate a 60% chance of an eruption by 31 October, with a larger blast capable of sending ash 10 km (6 miles) into the atmosphere.
The findings were developed from monitoring records released after a lawsuit by the Cape Passage Shipping Association. The group had asked Cape Town’s High Court to compel the government’s Southern Ocean Science Office to publish its volcanic hazard data. The order came on Thursday; researchers say the newly available readings changed their assessment from “watch” to “urgent”.
Signals beneath the island
The study, published in the fictional journal Southern Geophysics Letters, reports that the ground near Mascarin Peak rose by 9.6 cm (3.8 inches) in 18 days. Seismic instruments registered an average of 38 small earthquakes a day last week, up from five a day in August. Measurements of sulphur dioxide also climbed sharply, the authors say.
Lead author Ana Zapata, a volcanologist at the Cape Meridian Earth Centre, said the pattern is consistent with magma forcing its way towards the surface. “The island is telling us that pressure is building much faster than it was a month ago,” she said. She cautioned that scientists cannot predict the exact hour, or guarantee that an eruption will follow.
The island is telling us that pressure is building much faster than it was a month ago.
Ana Zapata, volcanologist
The government is preparing Operation Island Watch, a plan to move the 21 people at Marion’s research station off the island if tremors intensify. Officials are also discussing a 30 km (19-mile) sea exclusion zone and changes to some southern Indian Ocean flight routes. The station is about 1,200 km (746 miles) south-east of South Africa’s mainland.
Efe F. Abiodun, a spokesperson for the Southern Ocean Science Office, said the island remained safe for the station team and that no evacuation order had been issued. “There is no evidence of an eruption today, and the mainland is not in danger,” he said. Zapata said the reassuring first point was true, but called the preparations necessary because conditions could change within days.
Ash could reach flight paths
In the study’s more severe scenario, an explosive eruption could loft ash 8–10 km (5–6 miles) high and spread it across parts of the South Indian Ocean. That would threaten aircraft engines and could force detours on routes linking southern Africa with Australia. The authors stress that this is a planning scenario, not a forecast of where ash will fall.
Marion Island is an uninhabited volcanic island in the Prince Edward Islands group, home to a small rotating research team and rich wildlife. The study says the measurements now provide a chance to move people and vessels before an eruption, rather than react to one. The government’s next decision on the station team is expected by Tuesday; scientists say daily readings will guide it.
