The Relationships Between Plume Dynamics and Volcanic Electrification as Measured by a Lightning Mapping Array: a Case Study of Sakurajima Volcano, 2015

The role of volcanic lightning in plume monitoring and hazard mitigation has increased in recent years. Development of the high-definition lightning mapping array (LMA) and recent advancements in video analysis have allowed us to examine the relationships between detailed lightning statistics and plume measurements. In this work we describe the results of a case study of Sakurajima Volcano in 2015. Over 200 events were recorded using both the Lightning Mapping Array and a FLIR camera. By applying an optical-flow algorithm to the FLIR data we created Rise-diagrams (which give insight on initial velocity and maximum plume height) and Tacho-diagrams (which allow us to calculate the initial velocity of the plume, the peak flux rate, and the cumulative volume of the plume). We take a detailed look at the relationships between the plume dynamics derived from these diagrams and the type and amount of volcanic electrification. We use multi-variable logistic and linear statistical regressions to determine the probability relationships for the occurrence of volcanic electrification and to calculate the scaling relationship between the amount of electrification and the measured plume parameter