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Predicting volcanic eruptions early enough to warn authorities and nearby communities remains one of the biggest challenges in volcanology. A study published in Nature Communications describes a new detection technique called "Jerk," developed by researchers and engineers from the Institut de Physique du Globe de Paris (IPGP) and the GFZ Helmholtz Centre for Geosciences. The method relies on a single broadband seismometer to detect extremely subtle ground movements linked to magma intrusions deep underground.
These faint signals can reveal the earliest stages of volcanic activity in real time. The research team tested the method for ten years at a volcanological observatory on the island of La Réunion. During that period, the system successfully forecast 92 % of the 24 eruptions that occurred between 2014 and 2023. Warning times ranged from just a few minutes to as much as eight hours before an eruption began. About 14 % of the alerts did not result in eruptions. However, those alerts still detected magma movements beneath the volcano. Because it requires relatively little equipment, the Jerk system could become an important early warning tool, particularly for volcanoes that are not closely monitored.
Why Predicting Volcano Eruptions Is Difficult
Volcanoes often show warning signs before erupting. These may include increased seismic activity, deformation of the ground, and changes in volcanic gas emissions or composition. While these signals are well known, accurately interpreting them remains difficult. Scientists still struggle to determine exactly when an eruption will occur, how long it will last, and how powerful it might be.
False alarms also pose a serious problem. Incorrect warnings can cause costly evacuations, economic disruption, and public distrust of monitoring systems. As a result, improving the reliability of eruption forecasts is a major goal for scientists studying volcanic hazards.
Detecting Subtle Ground Motion From Rising Magma
Many previous approaches to eruption forecasting rely on probabilistic analysis, meaning they search for statistical relationships in large sets of monitoring data. In contrast, the new approach developed by a team led by Dr. François Beauducel from the Institut de Physique du Globe de Paris and Dr. Philippe Jousset from the GFZ Helmholtz Centre for GeoResearch in Potsdam focuses on directly detecting physical signals associated with magma movement.
The "Jerk" method identifies extremely small ground motions that occur when magma intrudes into the crust. These signals appear as very low frequency transients i.e. impulse like transition or settling signals recorded in horizontal ground motion, including both acceleration and tilt. According to the researchers, these signals likely originate from dynamic rock fracturing processes that take place before an eruption.
Scientists first identified these signals more than a decade ago while analyzing extensive datasets from previous eruptions of the Piton de la Fournaise volcano on La Réunion. The signals are extraordinarily small, measuring only a few nanometers per second cubed (nm/s3). Even so, they can be detected with a single very broadband seismometer.
The system includes specialized data processing that i.e. corrects for factors such as Earth tides. When the characteristic signal exceeds a certain threshold, the automated system immediately issues an alert.
A Decade of Real Time Volcano Monitoring
The system was installed in April 2014 at the Piton de la Fournaise volcanological observatory operated by the Institut de Physique du Globe de Paris (IPGP) of the Université Cité Paris (OVPF-IPGP, Reunion Island). The tool functions as an automated component of the WebObs monitoring system and uses data from a broadband seismological station belonging to the global Geoscope network located 8 km from the volcano summit (Rivière de l'Est).
The first alert occurred on June 20, 2014. The system issued a warning 1 hour and 2 minutes before the eruption began.
Over the following decade, the Jerk detection system operated continuously. It generated automatic alerts for 92% of the 24 eruptions recorded between 2014 and 2023. Depending on the event, warnings were issued anywhere from a few minutes to 8.5 hours before magma reached the surface.
Piton de la Fournaise is one of the most heavily monitored volcanoes in the world, making it an ideal location for testing the new method. Scientists were able to confirm Jerk alerts using other monitoring indicators, including seismicity, ground deformation, and volcanic gas measurements. These independent observations verified that magma intrusions had taken place and that the probability of an eruption was high. The system was also evaluated using historical data from 24 eruptions between 1998 and 2010, where the Jerk signal consistently appeared before eruptive events.
"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.
Understanding False Positive Alerts
Although the system performed well overall, some alerts did not lead to eruptions. These "false positives" occurred in 14 % of the cases when the system raised an alarm. However, further analysis showed that these events were not random errors. Instead, they corresponded to genuine magma intrusions that did not ultimately produce eruptions. Scientists sometimes refer to these events as "aborted eruptions."
Additional observations such as seismic activity, ground deformation, and volcanic gas measurements confirmed the presence of magma beneath the volcano during these alerts. "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.
A recent example occurred during a seismic crisis at Piton de la Fournaise on December 5, 2025. Alongside small deformation changes and gas anomalies, scientists recorded a weak Jerk signal measuring only 0.1 nm/s3. This signal confirmed that magma had intruded beneath the volcano.
Testing the Method on Other Volcanoes
After more than a decade of continuous real time monitoring on La Réunion, researchers believe the Jerk system could serve as a practical early warning tool for other volcanoes, particularly those with limited monitoring infrastructure.
The team plans to expand testing of the method to additional active volcanoes. One of the first targets will be Mount Etna in Italy. The project "POS4dyke" will deploy a new network of broadband seismometers from the GIPP Geophysical Instrumental Pool of Potsdam to detect Jerk signals. Installation is expected to begin in 2026 in collaboration with the INGV (Italy).
The work will also connect with the SAFAtor project, which is exploring how optic fibre cables can be used to improve early warning systems for earthquakes and volcanic eruptions. Together, these efforts could significantly enhance scientists' ability to detect and forecast volcanic activity around the world.
