Calving events at Thwaites Glacier, which is shedding vast amounts of ice, are detected from up to 1,600 kilometres away.

Seismic ‘icequake’ data might allow scientists to study ice loss from a notoriously unstable glacier in Antarctica.

Thwaites Glacier in fast-melting West Antarctica has the potential to contribute more than half a metre to global sea-level rise. But Thwaites’s melt rate depends on how and when new icebergs calve, or break away, from the glacier — a process that’s not easily observed.

Paul Winberry at Central Washington University in Ellensburg and his colleagues used vibration data from seismographs at seven stations across West Antarctica to identify a large potential calving event. Satellite imagery from the days and hours surrounding this seismic activity confirmed the team’s suspicions: the icequakes had been caused by new icebergs sloughing off the glacier’s front.

Similar techniques have been used to study ice loss in Greenland and other parts of Antarctica, but this is the first time that seismic monitoring has identified a calving event at Thwaites. The researchers say the method could help them to understand why the glacier is losing ice at such an alarming rate.