Researchers from the Institut de Physique du Globe de Paris and GFZ Helmholtz Centre have created a Jerk detection method that identifies subtle ground movements from magma intrusions using a single broadband seismometer. Tested over a decade at Piton de la Fournaise on La Réunion, the system forecasted 92% of 24 eruptions between 2014 and 2023, providing warnings from minutes to eight hours ahead. About 14% of alerts detected magma movements without resulting eruptions.
Predicting volcanic eruptions reliably has long challenged scientists, who monitor signs like seismic activity, ground deformation, and gas emissions. A study in Nature Communications introduces the Jerk method, which detects very low-frequency transients in horizontal ground motion, measuring a few nanometers per second cubed (nm/s³). These signals stem from rock fracturing due to magma pushing underground, captured by one broadband seismometer after correcting for factors like Earth tides. An alert triggers when the signal exceeds a threshold in the automated WebObs system. Installed in April 2014 at the Piton de la Fournaise observatory, operated by IPGP on Réunion Island, the first alert came on June 20, 2014, 1 hour and 2 minutes before eruption. From 2014 to 2023, it alerted for 92% of 24 eruptions, with warnings up to 8.5 hours. Independent checks via seismicity, deformation, and gases confirmed high eruption probability during alerts. The 14% non-eruptive alerts matched confirmed magma intrusions, termed aborted eruptions. A December 5, 2025, seismic crisis showed a 0.1 nm/s³ Jerk signal with deformation and gas changes. Dr. Philippe Jousset of GFZ noted: 'The great originality of this work lies in the fact that the Jerk method was tested and validated in real time in an automatic and unsupervised manner for more than 10 years.' He added: 'In addition to the effectiveness of the Jerk alert for eruptions, the tool proves to be a perfect and unequivocal detector of magmatic intrusions.' Historical data from 1998-2010 also showed consistent pre-eruption Jerk signals. With minimal equipment needs, the method suits under-monitored volcanoes. Testing will expand to Mount Etna in Italy starting 2026 via the POS4dyke project with INGV.
