We are powerless in the face of natural forces

In addition to your work with students, you have pursued your own research projects. Your research focuses on lightning. What is the connection between lightning and volcanos?

Lightning is phenomenon that is normally associated with storm clouds. Pliny the Younger, who described the explosive eruption that destroyed Pompeii, also mentions the lightning flashes that accompanied it. Volcanic eruptions have been observed and reported by many people, but our research program at LMU is nevertheless relatively new. Our basic assumption is that lightning is not a random feature of eruptions, but is directly connected with them.

We began to study the phenomenon in our laboratory in the Theresienstraße: Particles of volcanic ash are accelerated into a shock tube and imaged with the aid of a high-speed camera. This enables us to observe the properties of the discharges that develop in the ash cloud. The next stage will involve observations in the field with a view to identifying the parameters responsible for generating the lightning. As part of a large-scale project funded by a grant from the European Research Council (ERC), we have developed a unique set of instruments, with which we can measure and analyze these flashes. We used them on Cumbre Vieja, which provided an unmatched kick-off opportunity for our project.

Can you summarize your initial results?

So far, we have confirmed that the numbers and the sizes of the volcanic ash particles both play a role in determining whether or not lightning flashes are generated – the smaller the particles, the higher the number of flashes.

In the course of our observations, we repeatedly asked ourselves whether or not the size of an eruption has an impact on the generation of lightning. On La Palma, we had the chance to experience a relatively small-scale, explosive eruption, which produced lots of lightning flashes. This essentially confirms our basic assumption. Virtually all eruptions have an inherent tendency to generate lightning. So we now need to exhaustively test and characterize our instrumentation.

How do you go about this in the field?

When we realized that an eruption was imminent, we immediately took the necessary organizational steps to ensure that we could take our instruments with us. On the island, we were in regular consultation with the local authorities and scientists. We were able to set up our instruments in the restricted zone and began to make measurements. The original idea was to bring the instruments back with us, but the collaboration with our local colleagues worked so well that we left them there. We are now working in close cooperation with the researchers on the ground, and we receive all the necessary data from them, which we are now analyzing.

Another aim of our project is to enhance the capabilities of the instruments we have developed, so that they can become part of the standard portfolio of an integrated monitoring package. Their use in the context of an ongoing eruption is an ideal setting in which to demonstrate what they can do.