Every 26 seconds, a faint seismic pulse travels through the Earth, producing a vibration so subtle that no human can feel it. Scientists have been investigating this mysterious rhythm for more than 60 years.

First identified in the early 1960s by geologist Jack Oliver, the signal originates in the Gulf of Guinea, off the western coast of Africa. Sensitive instruments have detected its distinctive rhythm thousands of miles away.

Unlike an earthquake, the phenomenon produces tiny, rhythmic vibrations called microseisms. But what causes such a persistent and regular pulse?

For decades, researchers have debated whether ocean waves, volcanic activity, or underground fluids might be responsible.

A study published in April 2026 in Nature Communications offered an important clue. 

Researchers discovered that bursts of the 26-second signal coincide with powerful ocean swells generated by distant storms in the Southern Ocean.

They proposed that the waves may stimulate fluid-filled cracks beneath the seafloor, causing them to vibrate at particular frequencies, much like a musical instrument responding to the right note.

The precise mechanism remains under investigation, but the discovery brings scientists closer to explaining one of Earth's most persistent seismic mysteries.