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Estimating lava lake and exposed magma conduit levels using satellite-derived volcanic radiative power.

Adam Cotterill 1

Abstract

Open-vent volcanoes represent a direct connection from magma storage regions to the surface and provide excellent opportunities for scientists and geo-tourists to observe volcanic processes. However, the often benign activity can shift to eruptive behaviour, sometimes rapidly and unexpectedly, and this transition is difficult to forecast even at well-monitored systems. At volcanoes hosting lava lakes, the lake level has been linked to system pressure, with high pressure being related to higher eruptive potential. Monitoring lava lakes and exposed magma columns therefore provides helpful information for eruption forecasting. However, at systems where ground-based monitoring is precluded alternative approaches are needed. Here, a new simple method using volcanic radiative power (VRP) to estimate the height of lava lakes and exposed magma columns is presented. VRP is a measure of the energy emitted by volcanoes, typically calculated from satellite-retrieved middle infrared measurements. VRP varies depending on the temperature and radiating surface of a lava body, and so by assuming one variable the other can be calculated. By assuming a simple flaring cone geometry, the estimated radiating area allows the calculation of an approximate level of a lava body within a crater. Preliminary results from Manam volcano, Papua New Guinea during the 2018--2021  elevated eruptive period shows the magma column frequently rising into Manam's South Crater.  An estimated intra-crater magma level of 1 metre on 17/05/2019 agrees with the only visual observation of South Crater on 20/05/2019[AC1] . Future development includes extensive ground truthing, and development with real geometry and non-flaring cone geometries.