Beginning on June 8, 1783, the multi-year eruption of the volcanic system including Grímsvötn and Þórðarhyrna (sometimes referred to in Icelandic as the Skaftáreldur, Skaftá Fires) filled the river valley with lava, including a gorge thought to have been deep, diverting its flow into the multiple shallow channels that now characterize its course. As a result it is subject to jökulhlaups (glacial outburst floods), which occur every one to two years. The 2015 flood was unusually damaging, the largest since records began.