a supervolcano in yellowstone national park , a supervolcano releases around 45,000 metric tonnes of carbon dioxide each day .
but the magma chamber lying directly beneath its surface is not considered large enough to produce these levels , so researchers have been searching for an alternative source for years .
now , by tracking seismic waves , a team of geophysicists has discovered an enormous secondary chamber deeper underground that 's so large its partly-molten rock could fill the grand canyon 11 times over .