Seismologists have uncovered a peculiar phenomenon that reveals Earth is not as passive as it appears. Every 26 seconds, a faint seismic tremor, often referred to as Earth’s heartbeat, pulses through the planet. These microseisms, which are akin to tiny earthquakes but not identical, have baffled scientists for decades. Despite numerous theories, the source of this mysterious pulse remains unidentified.
The phenomenon was first documented in the early 1960s by geologist Jack Oliver, who speculated that the pulse might originate from the southern or equatorial Atlantic Ocean. However, due to the lack of advanced instruments, he was unable to investigate further. Michael Ritzwoller, a seismologist at the University of Colorado, Boulder, noted that Oliver’s resources were limited to analog paper records, a stark contrast to the digital seismometers available today. Since Oliver’s discovery, scientists have devoted significant time to understanding this mystery, yet Earth’s heartbeat continues to elude definitive explanation.
Lars Eivind Augland, an associate professor at the University of Oslo, described the 26-second pulse as a regular tremor within Earth’s crust. Although these tremors do not pose a threat like typical earthquakes, they are consistently recorded by seismic stations globally, particularly in regions like West Africa, North America, and Europe. Theories explaining Earth’s heartbeat have ranged from ocean waves and volcanic activity to fractures in sediment layers beneath the seafloor.
One of the initial explanations for the pulse was linked to wave activity in the Gulf of Guinea, West Africa. Augland and other researchers suggested that specific conditions, such as the ocean floor’s geometry and wave resonance on the seabed, might propagate these tremors through Earth’s crust. In 2013, Garrett Euler, a student presenting at the Seismological Society of America conference, supported this theory by pinpointing the Bight of Bonny as a potential source of the pulse. However, this hypothesis was later dismissed by most experts.
Another proposed explanation involved volcanic activity. Yingjie Xia from the Institute of Geodesy and Geophysics in Wuhan argued that the pulse might be connected to volcanoes near the island of São Tomé in the Bight of Bonny. Yet, this theory also failed to gain widespread acceptance.
Augland eventually introduced a third possibility: sediment fractures beneath the seafloor. He cited a study published in Earth and Planetary Science Letters, which suggested that fluid flowing through fractal fissures in these sediments could generate the tremors. Despite these varied theories, no explanation has been definitively proven.
Interestingly, Earth’s heartbeat is not the only mysterious phenomenon linked to the planet. A high-frequency buzzing sound, known as “The Hum,” has also puzzled geologists. This hum, like the 26-second pulse, has been heard by some people worldwide, but no satisfactory explanation has been found for either.
The mystery of Earth’s heartbeat continues to intrigue scientists, highlighting the complexities of our planet and the ongoing challenges in understanding its deeper mechanisms.