Seismologists are helpless before the strange event: Every 26 seconds, the Earth "beats" a beat

Since the early 60s, scientists have discovered strange beats. The mystery still exists until now without a satisfactory answer.

Every 26 seconds, the Earth shakes. The vibration was not strong enough for us to notice, but loud enough that seismometers located on the continents recorded a strange "rhythm". Scientists have known about the existence of this rhythm for a long time, but so far we have not had a reasonable explanation.

This beat - also known as "microseism" in the dictionary of seismology - was first recorded in the early 1960s by researcher Jack Oliver, then. He is now working at the Lamont-Doherty Geological Observatory. According to him, the beat comes from "the South or the equatorial region of the Atlantic Ocean"; The rhythm will be stronger in the summer months of the Northern Hemisphere (also the winter months of the Southern Hemisphere regions).

Seismologists are helpless before the strange event: Every 26 seconds, the Earth "beats" a beat
Seismologists are helpless before the strange event: Every 26 seconds, the Earth "beats" a beat

"In 1962, Jack didn't have the resources we had in 2005 - he didn't have an electronic seismometer, he had to study with paper data," said Mike Ritzwoller, a seismologist. working at the University of Colorado, said.

In 1980, geologist Gary Holcomb analyzed the data more closely and discovered a new feature: microscopic earthquakes are stronger when storms occur. Then, both Oliver's predecessor's work and Holcomb's discovery faded over time.

Until 2005, the mystery was once again brought to light by a recent graduate, Greg Bensen at the University of Colorado. Mike Ritzwoller, now a mentor to Bensen, analyzed the data with the student and discovered something strange: there was a strong signal emanating regularly from a distant area.

"As soon as we saw it, we realized there was something strange, but we didn't know what it was," Professor Ritzwoller said.

A seismometer, an instrument that measures the "breathing rate" of the Earth.
A seismometer, an instrument that measures the "breathing rate" of the Earth.

After ruling out everything from faulty instrumentation to miscalculation, they confirmed the strange seismic activity did indeed exist. Using triangulation, the team pinpointed the source of the pulse: the Gulf of Guinea on the West African coast.

Combined with Oliver and Holcomb's earlier findings, the team published their scientific report in the journal Geophysical Research Letters in 2006. But since then, no one has been able to confirm what causes the seizures. this microscopic soil. Many people believe that the waves crashing on the shore cause earthquakes, while others think that volcanic activity creates the pulse of the earth.

Noise around us

Although this strange rhythm is regular and unanswered, earthquakes (not related to earthquakes or volcanic activity) are frequently present beyond the understanding of the vast majority of us. The Earth still regularly makes strange sounds that we do not know.

“Sounds caused by earthquakes persist because of [the impact of] the Sun,” explains researcher Ritzwoller. Heat from the bright star makes Earth's equator hotter than the poles, generating winds, storms, ocean currents, and waves. When the waves hit the shore, the energy generated from the collision spreads over the land. This phenomenon is similar to knocking on the table and causing the person sitting at the table to feel the vibration.

Based on the sounds caused by earthquakes, scientists can understand more about the structure of the Earth's crust. "But the observation of the rhythm in 2005 took us by surprise," Ritzwoller said.

Identify where the beat is coming from

Six years after the research report was published, another student achieved a breakthrough. This time it was Garrett Euler from the laboratory of seismologist Doug Wiens at the University of Washington. Euler narrowed the search and discovered that the pulse was coming from an area called the Bight of Bonny, located in the Gulf of Guinea. Euler also gave a reason why the waves crashing on the shore caused the strange seismic phenomenon.

As waves move over the sea surface, the difference in water pressure is not large enough to affect the sea floor. But when the water hits the shore, where water pressure will immediately have a strong effect on the Earth's crust, the pressure will deform the seabed and cause earthquakes. Euler published his findings at a seismological conference in 2013.

Strange beats appear.
Strange beats appear.

However, there are still doubts surrounding Euler's assessment. In the same year, another research report by the Wuhan Institute of Geophysical Surveys, China gave different results: a rhythm every 26 seconds was caused by volcanic activity. In the Bight of Bonny area, volcanoes on the island of São Tomé can completely cause strange phenomena. In Japan, the Aso volcano also caused a similar seismic rhythm.

There are still questions beyond this controversy. Why did the phenomenon take place in the Bight of Bonny? There are countless kilometers of coastline in the world and many other active volcanoes, right? Most volcanoes do not even cause such seismic rhythms, what is the difference between the volcano of São Tomé island or the volcano of Aso?

More than half a century after scientists first heard the strange pulse, the answer is still not certain. Many scientists believe that there are still aspects worth studying more in seismology, such as mapping the Earth's geology, while the strange pulse "doesn't make any sense for understanding the structure of the Earth's crust." soil".

However, Professor Ritzwoller still thinks this is a topic worth studying.

“We are still waiting for an explanation for this phenomenon. I think it's very interesting, and it represents that the Earth still hides strange phenomena that still lie behind the curtain of mystery." Perhaps this is the work of researchers of the next generation.

Google Tech News - DiscoverMag

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