In this episode, Drew discusses how earthquakes are detected long before most people ever feel the ground move. While earthquakes often seem sudden and unpredictable, the Earth actually sends out subtle physical signals as a fault begins to rupture. By understanding the physics behind those signals, scientists can detect earthquakes in real time and issue warnings seconds before the strongest shaking arrives.

The episode breaks down what an earthquake really is, starting with how stress builds up in Earth’s crust and how that energy is released as seismic waves. Drew explains the critical difference between fast-moving P-waves and slower, more destructive S-waves, and why the gap between them makes early warning possible. From there, the episode explores the tools scientists use to “listen” to the planet, including traditional seismometers, fiber-optic cables that double as massive vibration sensors, and experimental electrical and quantum-based detection methods.

Beyond the hardware, the episode looks at the challenge of separating real earthquake signals from constant background noise, and how modern algorithms and data processing make sense of overwhelming amounts of information in seconds. Ultimately, Listening to the Earth shows how physics, engineering, and computation work together to turn inevitable natural disasters into events we can respond to faster and more safely.