Dynamics, Monitoring, and Forecasting of Tephra in the Atmosphere

• Published in: Reviews of geophysics (1985) 2024-12, Vol.62 (4), p.n/a
• Main Authors: Pardini, F., Barsotti, S., Bonadonna, C., de’ Michieli Vitturi, M., Folch, A., Mastin, L., Osores, S., Prata, A. T.
• Format: Article
• Language: English
• Subjects: Air entrainment; Altitude; Ashes; Atmosphere; Aviation; Clouds; Eruptions; Forecasting; Fragments; Hazard mitigation; Health hazards; Low altitude; Mathematical models; Mixtures; monitoring; Numerical models; Plumes; Proximity; Risk; Risk reduction; Satellite instruments; Satellite tracking; Satellite-borne instruments; Satellites; Tephra; Volcanic activity; Volcanic eruptions; Volcanic plumes; volcanic plumes and clouds; Volcanoes
• ISSN: 8755-1209; 1944-9208
• DOI: 10.1029/2023RG000808

Explosive volcanic eruptions inject hot mixtures of solid particles (tephra) and gasses into the atmosphere. Entraining ambient air, these mixtures can form plumes rising tens of kilometers until they spread laterally, forming umbrella clouds. While the largest clasts tend to settle in proximity to the volcano, the smallest fragments, commonly referred to as ash (≤2 mm in diameter), can be transported over long distances, forming volcanic clouds. Tephra plumes and clouds pose significant hazards to human society, affecting infrastructure, and human health through deposition on the ground or airborne suspension at low altitudes. Additionally, volcanic clouds are a threat to aviation, during both high‐risk actions such as take‐off and landing and at standard cruising altitudes. The ability to monitor and forecast tephra plumes and clouds is fundamental to mitigate the hazard associated with explosive eruptions. To that end, various monitoring techniques, ranging from ground‐based instruments to sensors on‐board satellites, and forecasting strategies, based on running numerical models to track the position of volcanic clouds, are efficiently employed. However, some limitations still exist, mainly due to the high unpredictability and variability of explosive eruptions, as well as the multiphase and complex nature of volcanic plumes. In the next decades, advances in monitoring and computational capabilities are expected to address these limitations and significantly improve the mitigation of the risk associated with tephra plumes and clouds. Plain Language Summary During explosive volcanic eruptions, fragmented material known as tephra is forcefully injected into the atmosphere through volcanic plumes. While the largest clasts tend to settle in proximity to the volcano, the smallest fragments, commonly referred to as ash, can be transported over long distances, forming volcanic clouds. On the ground, tephra poses a significant hazard to human activities, both near the volcano and at distances up to hundreds of kilometers. In contrast, volcanic clouds present a serious threat to aviation. For these reasons, we are motivated to understand the dynamics of tephra plumes and clouds and how we can mitigate their hazards. Today, we have the capability to monitor tephra plumes and clouds using a plethora of techniques, ranging from ground‐based methods to satellite instruments. Moreover, forecasting of tephra dispersion through computer simulations has become a valuabl