A spectacular proof of our planet’s activity, calderas are huge topographic depressions, similar to flat-bottomed craters, with a diameter of several tens of kilometres. They are formed by large volcanic eruptions, and sometimes experience an inflation of their floor of up to a kilometre, caused by magma injection. This well-known process, dubbed “caldera resurgence,” has been observed several times and yet remains one of the least understood in volcanology. But why, after an eruption, does the arrival of new magma not produce another major eruption, but instead resurgence? A team of researchers from the University of Roma Tre, Italy, and the University of Geneva (UNIGE), Switzerland, shows that the non-erupted magma left after the caldera-forming eruption behaves as a “rubber sheet” that inhibits the rise to the surface of the newly injected magma. The research is published in Nature Communications.