Can lava flow like water? Assessing applications of critical flow theory to channelized basaltic lava flows

Journal of Geophysical Research - Earth Surface
By: , and 



Flowing lava and water have dramatically different physical properties but can form similar hydraulic structures, including undular hydraulic jumps, or standing wave trains. In water flows, undular hydraulic jumps are evidence of critical flow (Froude number ∼1) and open-channel hydraulic theory provides a powerful tool for estimating flow depth and velocity. Monitoring these parameters in an active lava channel is inherently challenging, but essential for calculating lava discharge (effusion rate), a primary control on the rate of flow front advance and ultimate flow runout distance. We analyze undular hydraulic jumps in both water and lava flows to assess the conditions under which they form and, by extension, the potential use of critical flow theory to estimate, in real time, lava flow velocity, depth, and discharge. Experimental data for water flows show that these structures mark the transition from supercritical to subcritical flow. Undular hydraulic jumps in the near-vent lava channel of the 2018 lower East Rift Zone eruption of Kīlauea, Hawaiʻi also reflect critical flow conditions; their wavelengths scale with flow depth and velocity, consistent with hydraulic theory. Calculated lava effusion rates are similar to estimates made using more traditional approaches (Jeffreys', 1925,, equation based on lava viscosity, density, and channel slope) and with lava volumes derived from topographic-change mapping. From this we conclude that critical flow phenomena show great potential to track flow dynamics and inform hazard assessment for a wide range of geophysical fluids.

Publication type Article
Publication Subtype Journal Article
Title Can lava flow like water? Assessing applications of critical flow theory to channelized basaltic lava flows
Series title Journal of Geophysical Research - Earth Surface
DOI 10.1029/2022JF006666
Volume 127
Issue 9
Year Published 2022
Language English
Publisher American Geophysical Union
Contributing office(s) Cascades Volcano Observatory, Volcano Science Center
Description e2022JF006666, 26 p.
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