Subglacial eruptions often cause jökulhlaups or great floods of water. In November 1996 the Grímsvötn Volcano beneath the Vatnajökull ice sheet erupted and caused a Jökulhlaup that affected more than and destroyed or severely damaged several bridges. During the ice ages, such floods from Lake Missoula were estimated to have discharges exceeding 17 × 106 m³/s (4.5 × 109 gal/s) and covered a third of eastern Washington state. Sonia Esperanca, program director in the National Science Foundation commented on the danger of subglacial volcanoes: When an ice-covered volcano erupts, the interplay among molten magma, ice and meltwater can have catastrophic results.