Hail formation triggers rapid ash aggregation in volcanic plumes
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 in 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 modeling demonstrate that volcanic hail formed rapidly in the eruption plume, leading to mixed-phase aggregation of ~95% of the fine ash and stripping much of the cloud out of the atmosphere within 30 minutes. Based on these findings, we propose a mechanism of hail-like aggregation that contributes to the anomalously rapid fallout of fine ash and the occurrence of concentrically-layered aggregates in volcanic deposits.
Citation Information
Publication Year | 2015 |
---|---|
Title | Hail formation triggers rapid ash aggregation in volcanic plumes |
DOI | 10.1038/ncomms8860 |
Authors | Alexa R. Van Eaton, Larry G. Mastin, M. Herzog, Hans F. Schwaiger, David J. Schneider, Kristi L. Wallace, Amanda B Clarke |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Nature Communications |
Index ID | 70174022 |
Record Source | USGS Publications Warehouse |
USGS Organization | Volcano Science Center |