Earth Sends Out a Mysterious Pulse Every 26 Seconds — No One Knows Why

Every 26 seconds, Earth produces a tiny seismic pulse. It is not strong enough to damage cities, shake homes, or alarm ordinary people, but sensitive instruments can hear it repeating again and again like a quiet planetary heartbeat.

Scientists have known about this strange signal for decades, yet its exact cause is still debated. The leading explanations point toward ocean waves striking the continental shelf near the Gulf of Guinea, or possibly volcanic activity near São Tomé, but no theory has fully closed the case.