Last September over 130 countries signed the Critical Test Ban Treaty (CTBT) completely prohibiting all explosions nuclear, anywhere on the planet. But for the treaty to be effective, its watchdogs need to be so good that any country considering a test on the sly will hold back out of fear of being caught. That means that an accurate-and absolutely dependable-network of monitors.

And so Thorne Lay, a seismologist at the University of California, Santa Cruz, and other CTBT scientists around the world are rewriting the book on bomb-spotting. Lay is chairing a US National Research Council panel appraising further research needed to properly enforce the ban, while international teams of scientists interlock stations into a sentinel that will stand guard over the planet, watching for covert blasts.