Thunderquakes can be used to map Earth's subsurface

Researchers have discovered that “thunderquakes”—seismic waves created when the energy from thunder hits the ground—can be used to map subsurface structures. This method functions similarly to an X-ray, potentially allowing scientists to monitor groundwater movement, environmental contamination, sinkholes, and building site foundations.

As part of the Penn State FORESEE project, the team utilized distributed acoustic sensing to transform standard telecommunications fiber-optic cables into thousands of vibration sensors. By using a laser-pulsing computer known as an interrogator, they were able to measure minute changes in the cable caused by vibrations.

Over a two-year period, the researchers used a fiber-optic cable exceeding two miles in length to identify 458 high-quality thunderquakes. This process provided unprecedented detail on air-coupled Rayleigh waves, which are seismic waves measurable at the surface that can be used to study deep subsurface environments.