Measuring Everest's Monster Avalanche
How big was the ice block that killed 16 Sherpas?
On April 18, 2014, a massive ice formation, known as a serac, broke apart on Mount Everest, triggering an avalanche of snow and ice that barreled through the Khumbu Icefall, a notoriously dangerous zone between Base Camp and Camp I, killing 16 Sherpas.
Until now the exact origin and magnitude of the ice block was unknown. To better understand the source of the tragedy, National Geographic's senior editor and cartographer Martin Gamache superimposed two satellite photos of Everest—one from April 7, 2014, and the other from April 26, 2014—on top of one another.
"There was a very large chunk of ice sitting there in the April 7 photo. You can see it outlined in orange [in the graphic above]. And you
