Sumit Chakraborty from Ruhr-Universität Bochum, the plenary speaker on Wednesday (12.07.2023) provided an interesting presentation on the hierarchy of the timescale of processes. What does that mean? Well, it means that different processes are working on different time scales. Sumit demonstrated this by showing the Keeling curve (Fig 1). The Keeling curve shows the change of the atmospheric CO2 concentration over time usually for the last 60 years. If you look at the change over time you see a sharp increase in the atmospheric CO2 concentration. However, if you only look at the variation within a year, you would observe a decrease and increase in the CO2 concentration. Consequently, it is important to considering the “correct” timescale to make inferences on the respective process and also consider the “correct” timescale to make inferences on the future, especially, in regards of climate change.

Knowing the timescales of processes is very important for natural hazard prevention. There are many cities build around volcanoes, for example Mt. Fuji in Japan, Mt. Vesuvius in Italy (pictured), and the Laacher See volcano in Germany, which all have the potential to cause catastrophic damages to people and infrastructure. In this case the past can be the key for the future. By looking at past eruptions it is for example, possible to infer the magma residence time of melts in a magma chamber. Sumit is one of the leading scientists in the field of diffusion chronometry which can do exactly that, inferring how long a process can take place. This is possible by looking at element concentrations on profiles along the mineral. Changes in the chemical composition from core to rim can be explained by the timescale of diffusion that is influenced by time, temperature, and the diffusion constant for a specific mineral and element (Fig 2).

Sumit’s group worked on the Laacher See volcano and were able to estimate that the melt stayed in the magma chamber between 14 days and one year (depending on the estimated temperature). Of course, this is a long time range attributed to some uncertainties, however, future studies might be able to generate more precise residence times which may help to better evaluate the time from the detection of seismic activity until the eruption. Such studies can potentially help to reduce the damage on civilians and infrastructure of cities close to volcanoes, even though we have not yet reached the precision to do so. Still, this depicts the power of knowing geological timescales and also the usefulness to look into the past to solve problems of the future.