Dataset Information

Hail formation triggers rapid ash aggregation in volcanic plumes.

ABSTRACT: 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.

SUBMITTER: Van Eaton AR

PROVIDER: S-EPMC4532834 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Hail formation triggers rapid ash aggregation in volcanic plumes.

Van Eaton Alexa R AR Mastin Larry G LG Herzog Michael M Schwaiger Hans F HF Schneider David J DJ Wallace Kristi L KL Clarke Amanda B AB

Nature communications 20150803

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 ...[more]

PMID: 26235052

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Project description:Little is known of the earliest stages of soil biota development of volcanic ash, and how rapidly it can proceed. We investigated the potential for soil biota development during the first 3 years, using outdoor mesocosms of sterile, freshly fallen volcanic ash from the Sakurajima volcano, Japan. Mesocosms were positioned in a range of climates across Japan and compared over 3 years, against the developed soils of surrounding natural ecosystems. DNA was extracted from mesocosms and community composition assessed using 16S rRNA gene sequences. Metagenome sequences were obtained using shotgun metagenome sequencing. While at 12 months there was insufficient DNA for sequencing, by 24 months and 36 months, the ash-soil metagenomes already showed a similar diversity of functional genes to the developed soils, with a similar range of functions. In a surprising contrast with our hypotheses, we found that the developing ash-soil community already showed a similar gene function diversity, phylum diversity and overall relative abundances of kingdoms of life when compared to developed forest soils. The ash mesocosms also did not show any increased relative abundance of genes associated with autotrophy (rbc, coxL), nor increased relative abundance of genes that are associated with acquisition of nutrients from abiotic sources (nifH). Although gene identities and taxonomic affinities in the developing ash-soils are to some extent distinct from the natural vegetation soils, it is surprising that so many of the key components of a soil community develop already by the 24-month stage. In this system, however, rapid development may be facilitated by the relatively moderate pH of the Sakurajima ash, proximity of our mesocosms to propagule sources, and the rapid establishment of a productive bryophyte and lichen layer on the surface. Ash from other volcanoes richer in acids or more distant from propagule sources could show a different pattern and slower soil biota development.

Dataset Information

Hail formation triggers rapid ash aggregation in volcanic plumes.

Publications

Hail formation triggers rapid ash aggregation in volcanic plumes.

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