What's been driving Hawaii's lava fountains?

In most cases, hotspot-driven volcanism is relatively sedate, with lava flowing down mountainsides slowly enough that people can walk out of its way. But in a number of locations—Mount Etna, Hawaii, Iceland—lava gets expelled in dramatic fountains that can reach several hundred meters in height.

Right now, we're not sure what powers them. However, thanks to a recent set of eruptions at the Kilauea volcano, we have some of the best documentation yet of erupting lava fountains. In a recent edition of Science, researchers from the US Geological Survey describe what we've seen and compare it with what we might expect based on our best ideas about what powers these fountains of molten rock.

With three active volcanic regions that engage in fountaining, there has been a steady flow of dramatic videos of red-hot molten rock spouting from the Earth. …