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Pāhoehoe flow cooling, discharge, and coverage rates from thermal image chronometry
Author(s) -
Harris Andrew J. L.,
Dehn Jonathan,
James Mike R.,
Hamilton Christopher,
Herd Richard,
Lodato Luigi,
Steffke Andrea
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl030791
Subject(s) - lava , geology , thermal , flow (mathematics) , volumetric flow rate , mechanics , atmospheric sciences , meteorology , volcano , physics , seismology
Theoretically‐ and empirically‐derived cooling rates for active pāhoehoe lava flows show that surface cooling is controlled by conductive heat loss through a crust that is thickening with the square root of time. The model is based on a linear relationship that links log ( time ) with surface cooling. This predictable cooling behavior can be used assess the age of recently emplaced sheet flows from their surface temperatures. Using a single thermal image, or image mosaic, this allows quantification of the variation in areal coverage rates and lava discharge rates over 48 hour periods prior to image capture. For pāhoehoe sheet flow at Kīlauea (Hawai`i) this gives coverage rates of 1–5 m 2 /min at discharge rates of 0.01–0.05 m 3 /s, increasing to ∼40 m 2 /min at 0.4–0.5 m 3 /s. Our thermal chronometry approach represents a quick and easy method of tracking flow advance over a three‐day period using a single, thermal snap‐shot.