Earth’s Heartbeat – The Mysterious Sound Generated Every 26 Seconds

Ever since the 1960s, seismologists on multiple continents have detected a mysterious pulse generated like clockwork, every 26 seconds. But in the last 60 years no one has been able to figure out what this sound actually is.

The “heartbeat of the Earth” was first documented in 1962, by John Oliver, a researcher at the Lamont-Doherty Geological Observatory, Columbia University. He figured out that it was coming from somewhere in the southern or equatorial Atlantic Ocean, and that it was more intense during the Northern Hemisphere’s summer months. Then, in 1980, Gary Holcomb, a geologist with the U.S. Geological Survey, also discovered the mysterious pulse, noting that it was stronger during storms. But for some reason, the two researchers’ discoveries remained virtually unknown for over two decades, until a graduate student at the University of Colorado, Boulder, once again detected the “heartbeat” and decided to look into it.

Photo: Tumisu/Pixabay

Mike Ritzwoller, a seismologist at the University of Colorado, recently told Discover Magazine that as soon as they laid eyes on the data of then-graduate student Greg Bensen, he and researcher Nikolai Shapiro knew there was something weird about the intermittent pulse. They got to work, analyzing the blips from every possible angle, analyzing the data, checking their instruments, and even triangulating the source of the pulse to a location in the Gulf of Guinea, off the western coast of Africa.

Ritzwoller and his team even dug up the research of Oliver and Holcomb and published a study on the mysterious pulse in 2006, but they were never able to explain what it actually was. One theory claims that it’s caused by waves, while another states that it’s due to volcanic activity in the area, but neither has yet been proven correct.

The wave theory dates back to 2011, when Garrett Euler,  a graduate student at Washington University in St. Louis, pinpointed the origin of the pulse to a part of the Gulf of Guinea called the Bight of Bonny, theorizing that when waves hit the continental shelf, the pressure deforms the ocean floor seismic, causing pulses that reflect the wave pattern.

Photo: Wikimedia Commons

Euler’s theory was pertinent, but not everyone was convinced by it. In 2013, Yingjie Xia, a researcher from the Institute of Geodesy and Geophysics in Wuhan, China, theorized that the source of the 26-second pulse was volcanic activity. His theory made sense as well. The origin of the signal was close to a volcano on the island of Sao Tome, and there was at least one other “microseism” somewhere else in the world that shared some similarities with this one.

But neither of the two theories fully explain pulse. Why does the 26 second pulse only occur in the Bight of Bonny? Waves hit coastlines all over the world, and there are plenty of other regions with seismic activity, what is so special about this place? Well, that’s one answer that no one has ever answered. And it’s not just that it’s a tough puzzle to crack, but also that seismologists don’t really seem interested it.

“There are certain things that we concentrate on in seismology,” seismologist Doug Wiens explained. “We want to determine the structure beneath the continents, things like that. This is just a little bit outside what we would typically study … [since] it doesn’t have anything to do with understanding the deep structure of the Earth.”

Photo: Yamaguchi先生/Wikimedia Commons (CC BY-SA 3.0)

But that shouldn’t take anything from the mystery of ‘Earth’s Heartbeat’, as there are definitely researchers working on solving its enigma. In the meantime, it’s somewhat nice to still have intriguing phenomena that science can’t fully explain yet.