How earthquake scientists eavesdrop on North Korea’s nuclear blasts

Waves and ripples in the Earth can reveal the location and depth of an explosion

illustration of seismic waves under a mountain

NUCLEAR SHAKEDOWN  Rumblings of seismic waves reveal clues about North Korea’s nuclear weapons tests, detonated in a mountain.

Nicolle Rager Fuller

On September 9 of last year, in the middle of the morning, seismometers began lighting up around East Asia.