Lightning volcanos or dirty thunderstorms have been reported in almost all major volcanic eruptions. Including the recent ones at Eyjafjallajökull (Iceland) in 2010 and Etna (Italy) in 2015.
What’s so new about this?
According to a study conducted in 2016, up until recently, the go-to method to detect a volcano lightning was to detect changes in the radio frequency radiation and the electric field generated by a volcanic plume. So if there was a way to detect a volcanic lightning, we could predict the properties of a plume to determine factors like ash content in the atmosphere. We could then use those critical pieces of information for safety measures like directing air traffic and public evacuation.
The study claims that factors like a lack of systematic instrumental observation and theoretical study of electrical activity inside a volcanic plume have been barriers to our understanding of this phenomenon.
But for the first time, the team behind the study headed by lead study author Corrado Cimarelli has successfully combined high-speed video footage of eruptions and acoustic measurements of Mt Sakurajima’s (Kyushu, Japan) electromagnetic field to declare the following significant findings.
- Volcanic lightning is the result of electrification of ash by lava.
- Its formation is due to a complex distribution of charge inside a volcanic plume.
- This lightning is observed only in the lower regions of a volcanic plume.
- It does not necessarily move downwards like normal thundercloud lightning.
- There is a connection between the total volume of ash released and the frequency of lightning flashes.
Note that this study is a significant advancement in our understanding of volcano lightning. Using the conclusions of this study, scientists can quickly indicate the presence of ash in the atmosphere. They can also provide information on the time evolution of volcanic plumes. And give authorities the ability to issue early warnings for the affected populace.
Featured image credits: Sergio Tapiro