As I write this, over 1,200 people are dead across Nepal and China, and nearly 5500 more are missing. About 900 people are trapped in hydropower tunnels clogged by debris. Herculean national and international efforts are being made to bring them out, but the tunnel entrances are sealed by dense plugs of compressed sediment, and rescuers have no idea of the extent of that blockage. An Australian tunnel expert summed up, “we might only have to dig 10 meters, or we might have to dig 100 meters.” [1]