Multiple eruptive events of Etna volcano in a short-time (Dec 2025 – Jan 2026) captured by high-precision borehole strain and tilt

Between late 2025 and early 2026, Mt. Etna exhibited highly diversified eruptive activity characterized by shifting eruptive styles. These phases were precisely captured by high-resolution signals from borehole strainmeters and tiltmeters. Starting on December 24th, borehole data highlighted an acceleration of the recharge phase marking an inflation, which culminated on December 26th in an attempt of summit intrusion, well-constrained by tilt signals from high-altitude stations.

In the early hours of December 27th, an effusive vent opened on the upper eastern flank of the Voragine (VOR) crater. Later, during the same day, two lava fountains occurred at the Northeast Crater (NEC), which had not generated paroxysms in the last 28 years. The strain and tilt networks detected distinct signals associated with these paroxysmal events, providing precise timing and first constraints on the underlying magmatic sources.

From December 29th through January 7th, 2026, strain and tilt signals recorded near-continuous decompression/deflation, accompanying effusive activity from vents located within the upper Valle del Bove depression at approximately 2.100 m a.s.l. In the last days of this phase, the signals indicated a waning of the decompression trend. These findings reaffirm the exceptional sensitivity of borehole strain and tilt monitoring in capturing diverse eruptive dynamics and providing critical real-time insights into volcanic processes.