In most cases, volcanism caused by hotspots is relatively quiet, with lava flowing down mountain slopes slowly enough for people to avoid it. But in a number of places – Etna, Hawaii, Iceland – lava is ejected in dramatic fountains that can reach hundreds of meters high.
At the moment we are not sure what drives them. However, thanks to the recent eruptions of the Kilauea volcano, we have some of the best documentation of erupting lava fountains to date. In a recent issue of Science, researchers at the US Geological Survey describe what we saw and compare it to what we might expect based on our best ideas about what’s driving these fountains of molten rock.
Years of wells
In three active volcanic regions where fountains form, there are always dramatic videos of glowing, molten rock spraying out of the earth. But Kilauea has only experienced three fountaining episodes since 1823, despite being the youngest and most active volcano in Hawaii. This activity has led to intensive studies and we have a good idea of the structure of the volcano. Previous work has identified some lava remnants within a few kilometers of the surface, and the volcano had 35 separate data collection stations on Kilauea, including “seismic, infrasound, geodetic, gas, and visual and thermal imaging cameras.”
After a major eruption in 2018 that partially emptied one of the underground lava reservoirs, there were signs that it was continually being refilled. However, starting in 2019, recharge accelerated, and the local peak rose at a rate of more than 22 cm per year. Then, in 2023, that doubled to 57 cm per year and spread to a nearby caldera.
