On June 6, 1961, geologist Oliver made the initial discovery of these periodic vibrations. He believed that they originated from the Earth’s mantle beneath the Atlantic Ocean and speculated that the tremors would be stronger in the Southern Hemisphere during winter.
However, current scientific consensus suggests that these regular vibrations are actually small earthquakes that have been narrowed down from the Atlantic Ocean to the subsurface of the Gulf of Guinea in West Africa.
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The rhythmic pulsations, also known as “microseisms” in the seismology dictionary, were first recorded in the early 1960s by researcher Jack Oliver while working at the Lamont-Doherty Geological Observatory. According to his observations, the pulsations originated from the “Southern or equatorial region of the Atlantic Ocean,” and they would be stronger during the summer months of the Northern Hemisphere (which corresponds to the winter months in the Southern Hemisphere).
The prevailing theory is that earthquakes are the release of energy from the Earth’s crust, resulting in seismic waves. However, there are numerous factors that can contribute to small earthquakes, including tectonic activity, volcanic eruptions, nuclear tests, and even human activities. Yet, these earthquakes do not follow a regular cycle, making it the first time scientists have encountered such a phenomenon of Earth shaking every 26 seconds.
Regarding the cause of the vibrations, scientists have not been able to provide a definitive explanation despite decades of research. Some scientists speculate that the true culprit behind the vibrations is the Sun, located 150 million kilometers away.
Garrett Uler, a scientist at the University of Washington, suggests that the Gulf of Guinea’s proximity to the equator and the Sun’s influence on the equator result in frequent interactions of ocean currents with the coastline of the Gulf of Guinea, causing extremely minor earthquakes. This situation can be likened to lightly tapping a table, causing the opposite end to vibrate.
However, not everyone agrees with this explanation. A group of Chinese scientists believes that the source of the 26-second periodic seismic activity is not caused by waves hitting the continental shelf but rather by volcanic activity. There is a volcano on an island near the Gulf of Guinea, and Japan’s Mount Aso has also caused small earthquakes in the past.
Nevertheless, both explanations fail to address a crucial question: If the periodic micro-earthquakes are caused by ocean waves or volcanic activity, why do they only occur in the Gulf of Guinea and not in other similar regions on Earth? There are many areas near the equator similar to the Gulf of Guinea, as well as numerous volcanic regions. So why do these regular earthquakes only happen here?
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Over half a century since scientists first heard these mysterious pulsations, the answer remains elusive. Many scientists believe that there are still aspects within the field of seismology that warrant further investigation, such as mapping the Earth’s geology, while the peculiar pulsations “hold no significance in understanding the structure of the Earth.”
In fact, in the field of science, there has long been a saying that “humans know more about the universe than about Earth” because reaching space only requires achieving escape velocity (which is approximately 7.9 km/s for Earth), but exploring the depths of the Earth requires drilling deep into the ground. To this day, the deepest human-made borehole has reached a depth of just under 13 km, barely penetrating the Earth’s crust, let alone the mantle and core.
The reason for this phenomenon is the excessively high temperature inside the Earth and the hardness of the rock layers. When a drill reaches a depth of 10,000 meters, the gravitational force of the Earth overwhelms the drill, making it impossible to drill deeper. At that point, drilling further into the Earth’s interior would be like using a noodle to puncture a rock.
As for drilling from the ocean floor, it is even more implausible because the deepest part of the Mariana Trench is less than 12 km, while the average thickness of the Earth’s crust is about 37 km. Therefore, drilling from the ocean floor under the high pressure of seawater is extremely difficult and poses unpredictable dangers.
Thus, in the near future, until there is a significant breakthrough in material technology, humans cannot truly explore the depths of the Earth. The unsolved mysteries within the Earth will remain shrouded in secrecy for a long time.