Publications

Ramsey, MS; Chevrel, MO; Coppola, D; Harris, AJL (2019). THE INFLUENCE OF EMISSIVITY ON THE THERMO-RHEOLOGICAL MODELING OF THE CHANNELIZED LAVA FLOWS AT TOLBACHIK VOLCANO. ANNALS OF GEOPHYSICS, 62(2), VO222.

Abstract
The application of thermo-rheological models to forecast active lava flow emplacement and quantify important eruptive parameters of older flows has become more common over the last decade. With the modification and adaption of these models to modular computing languages, they are now easier, quicker, and are being incorporated into studies of both terrestrial and planetary volcanism. These models rely on certain assumptions and input parameters, some of which such as emissivity are not well understood for molten materials. Without a well-grounded knowledge of how this parameter governs radiant cooling, remote measurements of temperature and models such as FLOWGO that rely on these temperatures to track cooling with time will be in error. Here, we perform a detailed FLOWGO-based modeling study of lava flows emplaced at Tolbachik volcano during the 2012-2013 and the 1975-1976 eruptions. Specifically, we have modified the FLOWGO model to incorporate a two-component emissivity model linked to the fraction of molten lava and cooled crust. We focus first on the large Leningradskoye Flow emplaced at the start of the 2012 eruption, relying on data from numerous other orbital sensors including MODIS, ASTER and ALI to constrain some of the model input parameters. The two-component emissivity adaption produced better fits to the final flow length, directly related to the crust cover percentage. We then applied the constrained model to the large Cone II flow formed in 1975, for which no satellite-based data are available. Results revealed that a nearly identical model fit was achieved with initial effusion rate of 700 m(3)/s or 1250 m(3)/s. However, for the higher the effusion rate, a lower the crust cover is needed to fit the flow length and width. This represents the first study to implement two-component emissivity into thermo-rheological modeling of lava flows. The results show that this is an important factor for model accuracy and critical for large, higher effusion rate flows as well as for our understanding of older flows on Earth and other planets.

DOI:
10.4401/ag-8077

ISSN:
1593-5213