Muon Imaging of Volcanic Conduit Explains Link Between Eruption Frequency and Ground Deformation

Understanding the physical mechanism of ground deformation at a volcano supports the use of deformation data as a monitoring tool. An inverse correlation was observed between eruption frequency and ground deformation of Sakurajima volcano from November 2018 to April 2021. Over the same period, the mass density of magma in the conduit was monitored via muography. Mass density increased during inflation, when eruption frequency was low, and decreased during deflation, when eruption frequency was high. Periods of low eruption frequency are associated with the formation of a dense plug in the conduit, which we infer caused the inflation of the edifice by trapping pressurized magmatic gas. Conversely, periods of high eruption frequency are associated with the absence of the plug, which we infer allows gas to escape, leading to deflation. Muography thus reveals the in-conduit physical mechanism for the observed correlation, with implications for interpretation of deformation at other volcanoes.

Automated summary

Understanding the physical mechanism of ground deformation at a volcano is important for utilizing deformation data as a monitoring tool. A study on Sakurajima volcano showed an inverse correlation between eruption frequency and ground deformation from November 2018 to April 2021. The study used muography to monitor the mass density of magma in the conduit and found that during inflation (low eruption frequency), the mass density increased, while during deflation (high eruption frequency), the mass density decreased. This study suggests that the presence or absence of a dense plug in the conduit plays a crucial role in the observed correlation between eruption frequency and ground deformation.