A Tidal Wave of Mud A mining dam collapsed and buried more than 150 people. Now Brazil is casting an anxious eye on dozens of dams like it. “No, it’s not that!” the friend said. “Run!” Dashing up a staircase, caked in mud and pelted by flying rocks, Mr. Castro clambered to safety. But as he watched, a wall of mud unleashed by the collapse of a mining dam swallowed his co-workers, he said. Tiago, George, Icaro — they and at least 154 others, all buried alive. The deluge of toxic mud stretched for five miles, crushing homes, offices and people — a tragedy, but hardly a surprise, experts say. That horrible.