Rapid Volcanic Ashfall Impact Assessment for the 2022 Hunga Eruption: a bespoke approach and lessons learned

When large, unprecedented disasters occur, rapid impact assessments can be used to release funds, mobilise aid and direct response priorities. The 15 January 2022 eruption of Hunga volcano, Tonga, and the resultant shockwave, ashfall and tsunami, caused substantive impacts across the Kingdom of Tonga. The provision of international aid was complicated by communications disruptions, and a need emerged for a rapid, remote volcanic impact assessment and the provision of specialist advice to inform the response of international partners.

This presentation outlines a bespoke rapid, remote volcanic impact assessment approach undertaken in the first 10 days post-eruption, using pre-existing vulnerability models, and progressively updating hazard (e.g. ashfall) and exposed asset (e.g. buildings, farms) data as it became available. There was considerable engagement with expatriate Tongans, and other technical experts, who provided important knowledge, insights, and local context to inform the process. We focused on assessing ashfall impacts to buildings, critical infrastructure, and agriculture, and estimated clean-up requirements on Tongatapu (the main island). These assets and undertakings are vital for community wellbeing and emergency response in the aftermath of ashfall events and had available geospatial datasets.

The methodology employed demonstrates the value of rapid, remote volcanic impact assessment to support international response and aid efforts, particularly considering the severe uncertainties apparent in the days immediately following an eruption. We highlight the challenges and successes of our approach, noting the need for data and tools that support rapid and longitudinal volcanic ashfall impact estimates in tropical and Pacific Island settings.