The 2010 eruption of Icelandic volcano Eyjafjallajökull proceeded through fits and starts. A new analysis by Tarasewicz et al. suggests that a downward propagating decompression wave triggered a cascade of explosive eruptions from sequentially deeper magma reservoirs. Drawing on detailed seismic measurements, the authors found that earthquake activity under the volcano propagated deeper into the subsurface as the eruption progressed. They found that at the onset of the explosive phase of the eruption on 14 April, magma was ejected from a chamber located 5 kilometers below the summit. Over subsequent weeks, the eruption calmed and the surface deflated as the subsurface magma chamber emptied. The authors suggest that the decreasing mass of the summit caused the pressure to drop in a subsurface pipeline that fed the main magma chamber.