Hail formation triggers rapid ash aggregation in volcanic plumes
نویسندگان
چکیده
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.
منابع مشابه
Ash aggregation enhanced by deposition and redistribution of salt on the surface of volcanic ash in eruption plumes
Interactions with volcanic gases in eruption plumes produce soluble salt deposits on the surface of volcanic ash. While it has been postulated that saturation-driven precipitation of salts following the dissolution of ash surfaces by condensed acidic liquids is a primary mechanism of salt formation during an eruption, it is only recently that this mechanism has been subjected to detailed study....
متن کاملEffects of vent overpressure on buoyant eruption columns: Implications for plume stability
Volcanic plumes resulting from explosive volcanic eruptions present a variety of hazards depending on their behavior. Buoyant plumes heat and entrain enough of the surrounding air to rise high into the atmosphere, disrupting air traffic and causing regional ash fall. Alternatively, collapsed plumes produce dangerous fast-moving lateral flows of hot ash and gas. The transition between these beha...
متن کاملDynamics of giant volcanic ash clouds from supervolcanic eruptions
[1] The largest explosive volcanic eruptions that have occurred on Earth generated giant ash clouds from rising plumes that spread in the stratosphere around a height of neutral buoyancy, with estimated supply rates that are in the range 10 to 10 m/s. These giant ash clouds are controlled by a balance between gravity and Coriolis forces, forming spinning bodies of nearly fixed proportions after...
متن کاملMonitoring and forecasting Etna volcanic plumes
In this paper we describe the results of a project ongoing at the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The objective is to develop and implement a system for monitoring and forecasting volcanic plumes of Etna. Monitoring is based at present by multispectral infrared measurements from the Spin Enhanced Visible and Infrared Imager on board the Meteosat Second Generation geosynch...
متن کاملNumerical models of caldera-scale volcanic eruptions on Earth, venus, and Mars.
Volcanic eruptions of gassy magmas on Earth, Venus, and Mars produce plumes with markedly different fluid dynamics regimes. In large part the differences are caused by the differing atmospheric pressures and ratios of volcanic vent pressure to atmospheric pressure. For each of these planets, numerical simulations of an eruption of magma containing 4 weight percent gas were run on a workstation....
متن کامل