Ingo Sonder

Investigating the conditions behind the formation of pyroclast textures and lava flow morphologies is important to understand the dynamics of submarine volcanic eruptions, which are hard to observe. The development of clast textures and lava morphologies depends on the competing effects of their eruption rates and the rates of solidification. While eruption rates are governed by subsurface magmatic processes, the solidification timescales depend on the rate of heat loss from lava to the external water. However, the effect of the speed of lava flow or clast on their solidification timescales under two‐phase (liquid water and vapor bubbles) water boiling conditions is poorly constrained. Using laboratory experiments with remelted igneous rocks, we investigate the effect of the relative motion between lava and external water on its cooling timescale. We use a range of water speed (0–12.5 cm s −1 ) in our experiments while keeping our sample stationary to simulate a range of relative speed between lava and ambient water. Using transient heat transfer modeling, we find that heat flux from the surface of the sample to the external water overall increases with increasing water speed. We find heat transfer coefficients of up to ∼1.72 × 10 3 W m −2 K −1 . The implications of high heat flux on the formation of solid lava crust under submarine conditions are discussed.