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Forecasting tephra impacts during the 2024 unrest at Awu volcano, North Sulawesi, Indonesia

Eleanor Tennant 1, Susanna F. Jenkins 1, Christina Widiwijayanti 1, Heruningtyas D. Purnamasari 2

  • Affiliations: 1 Earth Observatory of Singapore and Asian School of the Environment, Nanyang Technological University, 639798, Singapore 2 Center for Volcanology and Geological Hazard Mitigation, Bandung city, West Java 40122

  • Presentation type: Talk

  • Presentation time: Friday 09:15 - 09:30, Room S160

  • Programme No: 6.7.4

  • Theme 6 > Session 7

Abstract

After 20 years of repose, Awu volcano in Indonesia began a period of unrest in May 2022, which intensified in 2024 with increasing seismic activity and inflationary deformation. With five large (VEI ≥3) eruptions in the past ~300 years, and an island setting that concentrates populations within 40 km of the summit, Awu poses a significant threat to exposed communities. We evaluated the potential impacts of tephra fallout and large clasts from a VEI 4 eruption, the most likely scenario given the current unrest. Tephra, the most widespread and common volcanic hazard, can cause a range of impacts that include fatalities from large clasts near the vent to damage buildings and infrastructure tens of kilometers away. We focused on buildings, given their critical role in providing shelter, supporting livelihoods and facilitating recovery. Forecasting eruption impacts requires integrated assessment of hazards, exposure, and vulnerability, each with unique challenges.  To address these, we developed tailored methods for Awu volcano. We supplemented Awu's eruption history with data from analogue volcanoes to conduct probabilistic hazard assessment. This was combined with exposure information obtained from satellite optical imagery, where building typologies were classified from the pixel intensities. To derive vulnerability information for the building typologies present we employed Bayesian inference to integrate existing vulnerability models and propagate uncertainty in the analysis. The resulting forecasted impacts provide valuable planning information during this unrest stage, giving a foundation for targeted risk mitigation strategies that can contribute towards improving the resilience of communities living around the volcano.