Decadal persistence of cycles in lava lake motion at Erebus volcano, Antarctica

•We estimate the surface speed of Erebus volcano's lava lake using infrared images from 2004-2011.•The surface speed exhibits pulsatory behaviour with a period of ∼5-18 min throughout this period.•Arrival of gas bubbles at the surface is found to be uncorrelated with the phase of the speed cycles.•Instabilities in bi-directional flow of magma in the conduit may explain the observed behaviour.

Studies of Erebus volcano's active lava lake have shown that many of its observable properties (gas composition, surface motion and radiant heat output) exhibit cyclic behaviour with a period of ∼10 min. We investigate the multi-year progression of the cycles in surface motion of the lake using an extended (but intermittent) dataset of thermal infrared images collected by the Mount Erebus Volcano Observatory between 2004 and 2011. Cycles with a period of ∼5-18 min are found to be a persistent feature of the lake's behaviour and no obvious long-term change is observed despite variations in lake level and surface area. The times at which gas bubbles arrive at the lake's surface are found to be random with respect to the phase of the motion cycles, suggesting that the remarkable behaviour of the lake is governed by magma exchange rather than an intermittent flux of gases from the underlying magma reservoir.