Summary
Forecasting volcanic eruptions in time to alert authorities and populations remains a major global challenge. In a study published in Nature Communications, researchers and engineers from the Institut de Physique du Globe de Paris (IPGP) and the GFZ Helmholtz Centre for Geosciences present a new detection method, called “Jerk”, using a single broadband seismometer. It is capable of identifying, in real time, very early precursor signals of volcanic eruptions generated by subtle ground movements associated with magma intrusions. The researchers evaluated their method over a period of ten years at a volcanological observatory on the island of La Réunion. They were able to predict 92 % of the 24 volcanic eruptions that occurred between 2014 and 2023, with warning times ranging from minutes to eight hours. 14 % of the warnings turned out to be false positive: although they identified magma movements, these did not lead to an eruption. The Jerk tool thus promises to be a successful early warning method for predicting volcanic eruptions and, with its low instrumental requirements, offers a potential alternative especially for poorly monitored volcanoes.
Background: Signals before volcanic eruptions
Before volcanic eruptions, there are usually changes in the seismic activity, ground deformation and gas flows or gas composition. However, it remains a major challenge to use these signals to predict the probability and characteristics of a possible eruption – its timing, duration and strength. In particular, it is essential to avoid false alarms, which can be associated with high economic costs, social disruption and a loss of credibility.
New method for real-time detection of extremely subtle ground movements
Previous prediction approaches have often been probabilistic in nature, i.e. they search for statistical correlations in a large amount of measured data. A research team led by Dr. François Beauducel from the Institut de Physique du Globe de Paris, in collaboration with Dr. Philippe Jousset from the GFZ Helmholtz Centre for GeoResearch in Potsdam, is now proposing a direct approach that enables an automatic warning system: The “Jerk” method enables real-time detection of extremely subtle ground motions associated with deep magma injections.
The method is based on so-called “Jerk” signals. These appear as very low-frequency transients i.e. impulse-like transition or settling signals observed in horizontal ground motion, both in acceleration and tilt. The authors show that they are likely generated by dynamic rock-fracturing processes preceding an eruption.
The researchers had already discovered these Jerk signals more than ten years ago when analysing a large amount of data collected during past eruptions of the Piton de la Fournaise volcano on the island of La Réunion. They have amplitudes in the order of a few nanometres per second cubed (nm/s³) and can be detected using a single very broadband seismometer. Incorporating specific data processing that i.e. includes correction for Earth tides, the researchers have developed a warning system that gives alarm as soon as the characteristic signal exceeds a threshold value.
Ten-year time series of automatically collected data on La Réunion
In April 2014, the tool was implemented at the Piton de la Fournaise volcanological observatory, run by the Institut de Physique du Globe de Paris (IPGP) of the Université Cité Paris (OVPF-IPGP, Reunion Island) as a fully automated module of the WebObs system, using data from a broadband seismological station of the global Geoscope network located 8 km from the summit of the volcano (Rivière de l’Est). On June 20, 2014, a first alert was sent 1 hour and 2 minutes before the start of an eruption.
For more than 10 years, this Jerk signal detection and analysis system operated continuously, issuing automatic alerts for 92% of the 24 eruptions that occurred between 2014 and 2023. Warning times vary from a few minutes to 8.5 hours before the magma reaches the surface.
As Piton de la Fournaise is a heavily instrumented and monitored volcano, conditions here are almost laboratory-like. The data from the jerk tool could be validated using numerous other warning signs from the wide range of complementary observation data: they confirmed that a magmatic intrusion had actually taken place and that there was therefore a high probability of an eruption. The method was also tested a posteriori on data from 24 old eruptions between 1998 and 2010, showing that the Jerk alert works systematically.
“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, and not in post-processing of data as is the case in the vast majority of studies of eruptive precursors published in the literature,” explains Dr Philippe Jousset, co-author of the study and scientist in GFZ-Section 2.2 Geophysical Imaging.
Reporting and significance of false positive events
The system, however, sometimes produced “false positives” – clear alerts but not followed by eruptions. This occurred in 14 % of the cases where the alarm was raised. However, they all turned out to be real magma intrusions or “aborted eruptions”, an interpretation consolidated by all the other observables such as seismicity, deformation and analyses of volcanic gases. “In addition to the effectiveness of the Jerk alert for eruptions, the tool proves to be a perfect and unequivocal detector of magmatic intrusions,” resumes Philippe Jousset.
This was also the case during the last seismic crisis at Piton de la Fournaise on December 5, 2025: associated with low deformations and gas anomalies, a small Jerk signal was emitted (only 0.1 nm/s3), confirming that a magma intrusion had indeed taken place.
Outlook: Use on Mount Etna and on poorly instrumented volcanoes
In principle, the researchers believe that, following the more than ten-year real-time run and successful evaluation on La Réunion, the Jerk tool could be used as a simple and effective method of early warning of volcanic eruptions on other volcanoes which are less well instrumented.
At the same time, the scientists want to further evaluate their method and in particular test it on other active volcanoes, starting with Etna (Italy) where the project “POS4dyke” aiming at detecting the Jerk signal will use a new network of broadband seismometers from the GIPP Geophysical Instrumental Pool of Potsdam. The deployment should begin in 2026, in collaboration with the INGV (Italy), and will be supported by the project SAFAtor, that researches the use of optic fibre cables for earthquake and volcanic eruption early warning.
Original study:
François Beauducel, Geneviève Roult, Valérie Ferrazzini, Aline Peltier, Philippe Jousset, Patrice Boissier & Nicolas Villeneuve. Jerk, a promising tool for early warning of volcanic eruptions. Nat Commun (2025).
https://doi.org/10.1038/s41467-025-66256-z
To keep informed of the activity of Piton de la Fournaise and the GIPP project:
https://www.ipgp.fr/observation/ovs/ovpf/
https://www.facebook.com/ObsVolcanoPitonFournaise
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