We developed a technique for determining paleoeffusion rates and emplacement times for submarine lava flows, using observations of flow morphology and estimates of eruption volume, eruption temperature, lava viscosity, and preflow topography. Using laboratory simulations, and correlating these results with sea-floor observations, four submarine lava-flow morphologies are considered to be diagnostic of specific effusion rates: jumbled, folded, and lineated sheets, and striated pillows. We applied this approach to the CoAxial flow, emplaced in less than 14 days on the Juan de Fuca Ridge in early summer, 1993, and we calculated an effusion rate of ∼100 m3/s, giving an emplacement time of ∼10 days.

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