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Lava flow hazard assessment at a frequently erupting, small island volcano using PyFlowGo: Manam Papua New Guinea

Adam Cotterill 1, Christopher Kilburn1, Emma Nicholson2

  • Affiliations:  1UCL Hazard Centre, Department of Earth Sciences, UCL, London, UK; 2School of Graduate Research, University of Waikato, New Zealand 

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 47

  • Programme No: 6.5.16

  • Theme 6 > Session 5

Abstract

Hazard assessments are key to mitigating the impact of effusive eruptions on local populations. They are particularly important for Small Island Developing States (SIDS) where populations[AC1]  are in close proximity to eruptive centres. One example is Manam, a frequently erupting, 10 km wide volcanic island in Papua New Guinea. Historical effusions have occurred from the volcano's summit craters and vents on its upper flanks. Most have fed flows down the island's four principal valleys. However, at least five undated eruptions have produced satellite cones near the coast, indicating the potential also for low flank eruptions close to the island's settlements. In 2018-2019 lavas from the main summit crater threatened two villages resulting in their relocation. This has prompted a reassessment of lava hazard across the island. Here we present the results of a new hazard assessment using the thermo-rheological model PyFlowGo. We found that summit-fed flows channeled via the main valleys are unlikely to impact settlements directly, although high effusion rates could produce flows long enough to enter the sea and to create "laze" (lava haze) which could affect settlements across the island. We show that northeast valley lava flows are capable of inundating populated areas but that this requires either a change in the Main Crater morphology, a high effusion rate [AC2] or a new northeast valley flank vent. Our modelling reveals the highest threat is posed by satellite cone eruptions which have previously formed close to current settlements but the probability of such eruptions has yet to be established.