Catherine Cardon : Connect in order to contact the contributor. Search Access content directly Footer. Sign in. Search Loading Search using SolR syntax. Search using SolR syntax Run the search. Ash sedimentation by fingering and sediment thermals from wind-affected volcanic plumes. Valentin Freret-Lorgeril 1, 2 , J. Gilchrist 1, 3 , Franck Donnadieu 4, 1 , A. Peyrin 4 , C. Hervier 4 , S.
Valade 7, 8. Department of Earth Sciences [Geneva]. Laboratoire Magmas et Volcans. Abstract en. Ash fallout and volcanic plume dispersion represent critical hazards for local and global human populations for minutes to years after the onset of an eruption.
Understanding the key processes governing the sedimentation of ash particles is a major challenge in modern volcanology from modeling and risk management perspectives. Remote sensing observations of mammatus and cloud veils from numerous eruptions over recent years as well as field observations of spatially discontinuous ash deposits are consistent with this prediction.
Indeed, this mode of ash sedimentation is predicted to be the predominant mechanism of fine ash removal for a significant fraction of eruptions in the geological records. Here, we use a novel combination of 3 millimeter-wavelength Doppler radar observations and time series of optical disdrometer data to characterize for the first time in real-time the time-varying structure and sedimentation properties of volcanic ash plumes under steady wind conditions.
As a case study, we apply this new method to weak short-lived plumes from Stromboli Volcano. Radar data also record intermittent periods of higher reflectivity i. From time series of radar signals and ground-based disdrometer measurements, together with simple analog experiments, we develop a conceptual model for intermittent sedimentation from wind-affected ash plumes.
