Kilauea eruption triggered by pressure built over a decade

The 2018 eruption of Kilauea Volcano was one of the largest volcanic events in Hawaii in 200 years. The eruption was triggered by a relatively small and rapid change in the volcano after a decade-long buildup of pressure in its upper parts, according to a U.S. National Science Foundation-funded study published in Nature Communications by geoscientists at the University of Hawaiʻi at Mānoa and the U.S. Geological Survey.

Using USGS Hawaiian Volcanoes Observatory data from before and during the 2018 eruptions at the summit and flank, the research team reconstructed the geologic events.

The eruption evolved, and its impact expanded, as a sequence of cascading events allowed relatively minor changes to cause major destruction and historic changes in the volcano. A cascading series of events of this type was not considered the most likely outcome in the weeks prior to the onset of the eruption.

"This form of tunnel vision, which gives less attention to the least likely outcomes, is a bias that can be overcome by considering the broader, longer history of the volcano," said Bruce Houghton, the Hawaii state volcanologist, a geoscientist at the UH Mānoa School of Ocean and Earth Science and Technology and study co-author. "For Kilauea, this consists of widening the scope to consider the types of behavior seen in the first half of the 20th century and perhaps earlier."

The data suggest that a backup in the magma plumbing system at the long-lived Puʻu ʻŌʻō eruption site caused widespread pressurization in the volcano, driving magma into the lower flank, according to Matthew Patrick, research geologist at the USGS and lead author of the paper.

"Our study demonstrates that eruption forecasting can be inherently challenging in scenarios where volcanoes prime slowly and trigger due to a small event, as the processes that build to eruption may be hard to detect and are easy to overlook on the scale of the entire volcano," said Patrick. "It is a cautionary tale against over-reliance on recent activity as a guide for future eruptions."