Instead they found a problem: the density of the earth in the pyramid is at least 20 per cent lower on one side than the other. “The pyramid is at risk of collapsing if something isn’t done,” says Menchaca. He presented his results at a conference on Teotihuacan at UNAM last month.
Menchaca believes the difference is caused by the south side drying out. He compares the pyramid to a sandcastle on a beach. “I can use slightly moist sand to make a sandcastle,” he says. “If I leave it exposed to the sun and touch it when it is dry, then it crumbles.”
Story: Frank Nowikowski, New Scientist | Photo: Harald Sund/Getty