Understanding and forecasting sudden explosive eruptions.

Area of Science:

• Volcanology
• Geophysics
• Earth Sciences

Background:

• Explosive volcanic eruptions with Volcanic Explosivity Index (VEI) ≤ 3 often occur with minimal precursor signals.
• These eruptions, including magmatic, phreatomagmatic, and phreatic types, result from rapid gas decompression.
• Understanding and forecasting these events is crucial due to their potential hazards.

Purpose of the Study:

• To analyze key precursory signals preceding recent VEI ≤ 3 explosive eruptions.
• To investigate the development (bottom-up vs. top-down) and timescales of precursory activity.
• To understand the processes and crustal locations leading to volcanic overpressure.

Main Methods:

• Examination of precursory signals from recent lethal and non-lethal explosive eruptions (VEI ≤ 3).
• Analysis of signal development, timescales, and comparison across different eruption types.
• Identification of generally applicable precursory signals and discussion of threshold-based forecasting.

Main Results:

• Key precursory signals were identified preceding recent explosive eruptions.
• Variations in the development and timescales of precursory activity were observed.
• Potential for exportable precursory signals and improved forecasting through threshold analysis was discussed.

Conclusions:

• Effective forecasting of explosive eruptions (VEI ≤ 3) requires better understanding of precursory signals and system pressurization.
• Three major challenges for the next decade include complete eruption forecasting, subsurface plumbing visualization, and enhanced monitoring networks.
• Improved forecasting relies on identifying applicable precursory signals and utilizing thresholds for eruptive transitions.