Olivier Bachmann, would you consider vacationing in the Gulf of Naples this autumn?

Magma is certainly present, and with it the risk of an eruption. The problem is that we do not know exactly how much 'eruptible magma' ¨C i.e. liquid magma that has crystallised only slightly ¨C the magma chamber beneath the Gulf of Naples holds at this point in time. In the Phlegraean Fields, very large quantities of magma have erupted in a single eruption in the past, but we cannot yet predict when the next so-called 'super-eruption' will occur. Statistically speaking, such an event is very rare, and I do not expect it to take place within the next few decades or even millennia. But over the long term, however, super-eruptions represent a huge problem for the four million people who currently live in this zone.

And due to the fact that super-eruptions are such rare events, we lack the data on which to base more accurate predictions. Smaller volcanic eruptions, on the other hand, are far more frequent. In the Gulf of Naples, they take place every few centuries ¨C while the last one occurred a good 500 years ago.

Whether small or large eruptions: thanks to monitoring, volcanic eruptions can usually be predicted a few days or even weeks before they actually happen. When magma rises in the earth's interior, it can be measured before it reaches the surface of the earth. Given that there are many regions with active volcanoes, for example in the Canary Islands, Iceland and Hawaii, we have a fair amount of empirical data available during the window of time immediately preceding an eruption. This data can be transferred to other areas and is therefore very valuable for predictions. In view of these monitoring capabilities, I am confident that the population and holidaymakers could be warned in good time in an emergency and, in principle, also evacuated.

The situation is different for another natural hazard in the Phlegraean Fields, namely earthquakes. While their prediction is difficult, the probability is relatively high. Minor earthquakes occur every day. I expect we will experience a serious earthquake with a magnitude greater than four or five in the coming decades. If the earth trembles at the bottom of the sea, there is even the risk of a tsunami. On land, the topography can cause landslides, which can incur additional destruction.

Although this type of natural hazard is unpredictable, I personally consider the risk acceptable when conducting field research or holidaying with my family in the Gulf of Naples. I am not a reckless person, but there is no such thing as zero risk of danger and hazards of any kind ¨C neither in Naples nor here in Zurich."