Communication Demands of Volcanic Ashfall Events

Abstract

Volcanic ash is generated in explosive volcanic eruptions, dispersed by prevailing winds and may be deposited onto communities hundreds or even thousands of kilometres away. The wide geographic reach of ashfalls makes them the volcanic hazard most likely to affect the greatest numbers of people. However, forecasting how much ash will fall, where, and with what characteristics, is a major challenge. Varying social contexts, ashfall characteristics, and eruption durations create unique challenges in determining impacts, which are wide-ranging and often poorly understood. Consequently, a suite of communication strategies must be applied across a variety of different settings. Broadly speaking, the level of impact depends upon the amount of ash deposited and its characteristics (hazard), as well as the numbers and distribution of people and assets (exposure), and the ability of people and assets to cope with the ashfall (resilience and/or vulnerability). Greater knowledge of the likely impact can support mitigation actions, crisis planning, and emergency management activities. Careful, considered, and well-planned communication prior to, and during, a volcanic ashfall crisis can substantially reduce physical, economic and psychosocial impacts. We describe the factors contributing to the complex communication environment associated with ashfall hazards, describe currently available information products and tools, and reflect on lessons from a range of case-study ashfall events. We discuss currently-available communication tools for the key sectors of public health, agriculture and critical infrastructure, and information demands created by ash clean-up operations. We conclude with reflections on the particular challenges posed by long-term eruptions and implications for recovery after ashfall.