2015/08/03 by Alexa R. Van Eaton, Larry G. Mastin, Michael Herzog +4 · 1 citation
Earth and Planetary Sciences · Environmental Science · #Meteorological Phenomena and Simulations #Atmospheric aerosols and clouds #Cryospheric studies and observations
paper · pdf · doi:10.1038/ncomms8860
openalex publication_date 2015/08/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/03
During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterized 'wet' eruption. The 2009 eruption of Redoubt Volcano, Alaska, incorporated water from the surface (in this case, a glacier), which is a common occurrence during explosive volcanism worldwide. Observations from C-band weather radar, fall deposits and numerical modelling demonstrate that hail-forming processes in the eruption plume triggered aggregation of ∼95% of the fine ash and stripped much of the erupted mass out of the atmosphere within 30 min. Based on these findings, we propose a mechanism of hail-like ash aggregation that contributes to the anomalously rapid fallout of fine ash and occurrence of concentrically layered aggregates in volcanic deposits.