New research published in Earth and Planetary Science Letters describes how scientists have used the world's largest array of seismic sensors to map a deep-Earth area of melting carbon covering 1.8 million square kilometers. Situated under the Western US, 350km beneath the Earth's surface, the discovered melting region challenges accepted understanding of how much carbon the Earth contains - much more than previously understood. The study, conducted by geologist at Royal Holloway, University of London's Department of Earth Sciences used a huge network of 583 seismic sensors that measure the Earth's vibrations, to create a picture of the area's deep sub surface. Known as the upper mantle, this section of the Earth's interior is recognized by its high temperatures where solid carbonates melt, creating very particular seismic patterns. "It would be impossible for us to drill far enough down to physically 'see' the Earth's mantle, so using this massive group of sensors we have to paint a