The Heartbeat of the Planet


Checking a person’s pulse is a way to know that the person is alive or how fast their heart is beating. A normal resting heart rate for adults ranges from 60 to 100 beats per minute. Generally, a lower heart rate at rest implies more efficient heart function and better cardiovascular fitness. For example, a well-trained athlete might have a normal resting heart rate closer to 40 beats per minute.

Every 26 seconds, the Earth pulses.

The Earth’s pulse is not enough that you can feel it. Seismologists in different places around the world have been measuring the pulses for decades, but they don’t know for sure what is causing it.  This pulse was first documented in the early 1960s.

In seismology, the term microseism is defined as a faint earth tremor caused by natural phenomena and it is sometimes referred to as a “hum.” According to Wikipedia, it should not be confused with the anomalous acoustic phenomenon of the same name. The term is most commonly used to refer to the dominant background seismic and electromagnetic noise signals on Earth, which are caused by water waves in the oceans and lakes.

Since then, digital seismometers have moved the research forward. It seems that it is strongest during storms but the pulse is constant. In 2005, Greg Bensen at the University of Colorado-Boulder noted a strong signal, coming from somewhere far off.  His team considered possible sources – instrument error, incorrect data analysis, or that this seismic activity was real. They were even able to triangulate the pulse to a single source in the Gulf of Guinea, off the western coast of Africa.

But is it caused by waves? Volcanic activity?

It’s interesting but not particularly shocking or new. There is seismic activity all the time, not just during an earthquake or volcanic eruption.

Another way to look at it is to point to the Sun which heats the Earth more at the equator than at the poles and creates winds and storms and ocean currents and waves. When a wave hits a coastline or the continental shelf, the energy is transferred to the land and the pressure deforms the ocean floor.

Other scientists still favor the volcanic explanation. The pulse’s origin point is close to a volcano on the island of São Tomé in the Bight of Bonny.

And other scientists say that why is the pulse there when there are other continental shelves and volcanoes around the world. Why aren’t there other pulses?

I like scientific studies that are still unsolved after more than a half-century. I like the mystery. And I like that the planet has a pulse.

If we look beyond our planet, astronomers think they’ve solved a cosmic mystery surrounding fast radio bursts – powerful emissions of radio waves in space. Astronomers believe they have been able to track a burst back to a type of dense star called a magnetar. Magnetars have more mass than our sun but are squeezed into an area about the size of Manhattan. They occasionally spew bursts of radio waves and that’s what’s been causing the mysterious phenomenon lately. The bursts aren’t dangerous to humans.

One theory before this was that it was an alien signal.  That one was less scientific but certainly more fun. It would really be exciting if the Earth’s pulse came from radio waves sent here by aliens. No one seems to be investigating that possibility though.

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A lifelong educator on and off the Internet. Random by design and predictably irrational. It's turtles all the way down. Dolce far niente.

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