The trigger mechanism that caused the 2018 Kilauea volcano eruption on Hawaii island has eluded scientists. However, a new NASA-funded study published earlier this week in Nature suggests that record-breaking rainfall earlier in the year and the subsequent increase in groundwater pressures may be to blame.
According to an article in Nature regarding the study, this eruption event of the Kilauea volcano began in 1983. For 35 years prior to the May 2018 event, magma rose up from Earth and emerged from an area called the “upper east rift zone.” However, during this eruption, the lower east rift zone opened up, and lava flows devastated the southeastern region of the island.
An article from NASA reports that researchers ruled out a common cause for this particular eruption event, which is increased pressure in the magma chamber. When pressure within the chamber is high enough, the magma can break through rock. Falk Amelung, study co-author and professor of geophysics at the University of Miami Rosenstiel School of Marine and Atmospheric Science, stated that they did not see evidence of “significant inflation in the year prior to the eruption.” This is what led the scientists to investigate precipitation patterns as a potential trigger for the event.
As Michael Manga writes in Nature, fault slips or new cracks within rocks create magma pathways. Increases in groundwater pressure changes can trigger both of these processes. Based on modeled pressure changes due to rainfall leading up to the eruption, the study shows that right before and during the eruption, the volcano’s pore pressure was at its highest pressure in nearly 50 years. Because of this, the study proposes that “weakening and mechanical failure of the edifice was driven by changes in pore pressure within the rift zone, prompting opportunistic dike intrusion and ultimately facilitating the eruption.”
Additionally, the study reports that statistical analysis of eruption occurrences also points to rainfall. Jamie Farquharson, the lead study author and researcher at the Rosenstiel School, told NASA reporters, “When we investigate Kilauea’s historical eruption record, we see that magmatic intrusions and recorded eruptions are almost twice as likely to occur during the wettest part of the year.”
NASA reports that this is the first time that scientists are considering rainfall to explain deep magmatic processes, more than one mile below the surface. The scientists are concerned that changes in rainfall patterns associated with climate change could impact volcanic activity worldwide. As Farquharson stated to NASA, “we expect that rainfall-induced volcanic activity could become more common.”