The Earth pulses every 26 seconds. It was a geologist named Jack Oliver who, in 1960, discovered this strange phenomenon of microseisms, explains the media Popular Mechanics. At the time, the man was working at the Lamont-Doherty geological observatory at Columbia University in New York and did not have advanced equipment allowing him to determine the causes of these vibrations. Since then, the mystery has persisted.
For some specialists, these pulsations could be compared to the heartbeat of our planet. They are so light that we do not perceive them, and they do not represent any threat. Captured by seismic stations around the world, these small rumblings are mainly heard through devices located in West Africa, North America and Europe. Since the discovery of this phenomenon, seismologists have formulated numerous theories to try to explain its origin.
Several possible avenues
Scientists agree to locate its source in an area of the Gulf of Guinea, the Gulf of Biafra. Some say that the vibrations would arise under the oceans in which the continental shelf – the underwater part which extends the continent – would act like an immense breakwater. So when waves hit the bay, they would create a resonance, which could propagate as seismic waves in the Earth’s crust.
For others, a volcano located nearby, on the island of São Tomé, is in fact the culprit. Indeed, a similar volcanic microseism has already been documented in Japan. Credible leads which, however, do not explain the almost mechanical regularity of the vibration. Numerous research missions on the subject are still underway, none having yet confirmed anything.
Beyond theories about its mysterious origin, this “earthly pulse” is a valuable source of information for geophysics: it makes it possible to study the way in which ocean waves generate seismic signals, and to analyze the interaction between the earth’s crust and ocean dynamics.
Researchers use these microseisms to refine seismic models and better understand the characteristics of the seabed, the propagation of waves, and the composition of deep layers. Enough to occupy many researchers for sixty more years.
