'Extinct' volcanoes that haven't erupted for tens of thousands of years may not actually be inactive, but silently accumulating huge reservoirs of magma to fuel future outbursts. This worrying revelation comes from a team of volcanologists at ETH Zurich in Switzerland, who mapped the geological history of the Methana volcano near Athens, Greece, across 700,000 years. They discovered a "bloom" of tiny zircon crystals coinciding with Methana's longest dormant period, which lasted more than 100,