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Quantifying Thermal Infrared Emission from Active Lava Surfaces to Improve Models of Effusive Volcanism

Thompson, James (2020) Quantifying Thermal Infrared Emission from Active Lava Surfaces to Improve Models of Effusive Volcanism. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Thermal infrared data of active lava surfaces provides important information including temperature and emissivity, as well as derived volcanological properties such as composition, particle size, heat budgets, and vesicularity. These data are routinely acquired at active volcanoes from the ground, air, and space, but most are saturated or limited in spatial and spectral resolution. To resolve these limitations and expand the utility of these observations, a new portable, ground-based, high-resolution system known as the Miniature Multispectral Thermal infrared Camera (MMT-Cam) was developed to investigate active volcanic processes. In 2017 and 2018, the MMT-Cam was deployed at Kīlauea volcano (Hawai'i) to acquire thermal infrared data of the Halema'uma'u Crater lava lake and Pu'u 'Ō'ō lava flows. The MMT-Cam data provided a unique opportunity to determine the relationship between the emitted radiance from high-temperature surfaces and the derived emissivity and temperature, all fundamental to flow propagation thermo-rheological models. In addition to the camera data, coincident spaceborne and airborne thermal infrared data were simultaneously acquired by NASA. The combination of these datasets enabled the relationship between derived thermal properties at different spatial and spectral resolutions and the accuracy of those measurements to be quantified. The MMT-Cam data analysis revealed that the primary emissivity absorption of basalts shift to higher wavelengths and shallows as the lava cools and forms a crust. During this transition, emissivity increased by ~14%, producing a decrease in total radiance and increase in temperature. The effect of varying emissivity during lava propagation and cooling was evaluated using the PyFLOWGO thermo-rheological model with a new temperature-dependent variable emissivity module. The results using the new module were validated using ground measurements of heat flux and channel width, with a strong correlation observed to both of these attributes. Comparing the results using this new module to those using the original constant emissivity module revealed that the heat flux decreases by at least 30% and the final runout distance increased by a least 5%. Acquiring this new high-resolution ground-based data has improved flow propagation modeling and reduced the uncertainties in downflow hazards assessments, thereby potentially lowering future risks posed to local populations.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Thompson, Jamesjames.thompson@pitt.edujot520000-0003-4540-5717
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairRamsey, Michaelmramsey@pitt.edu
Committee MemberHarbert, Williamharbert@pitt.edu
Committee MemberStewart, Brianbstewart@pitt.edu
Committee MemberShelef, Eitanshelef@pitt.edu
Committee MemberHarris, Andrewandrew.harris@uca.fr
Date: 16 September 2020
Date Type: Publication
Defense Date: 18 May 2020
Approval Date: 16 September 2020
Submission Date: 6 August 2020
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 279
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Geology and Environmental Science
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Emissivity Kīlauea Volcano Lava Flow Propagation Modeling MMT-Cam Spatial-Spectral-Temporal Analysis Thermal Infrared
Date Deposited: 16 Sep 2020 15:10
Last Modified: 16 Sep 2020 15:10
URI: http://d-scholarship.pitt.edu/id/eprint/39550

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