Detifoss is counted as the most powerful waterfall (volume x drop) in both Iceland and Europe. In spite of this, its average annual flow is only about 1/10 the average of Niagara Falls. However, if there is a volcanic eruption under the Vatnajökull ice cap, such as have occurred repeatedly in geological history, the average flow can increase enormously. Indeed, sometime 8-10,000 years ago and 3000 years ago, the flow was up to 40 times that of Niagara, and these events scoured out the Jökulsá á Fjöllum valley and created the canyon of Asbyrgi downstream. Even in modern days, the threat of volcanic events (e.g., from the volcano Bárðarbunga) under the glacier have resulted in closure of the park.